Biomedical subjects

C Farmer

Publications and source records attributed to C Farmer.

At least 19 recordsLinked to original sources

PubMed2005

Exogenous prolactin stimulates mammary development and alters expression of prolactin-related genes in prepubertal gilts.

The goal of this project was to determine whether recombinant porcine (rp) prolactin (PRL) can enhance mammary development when given to pre-pubertal gilts and/or modify the expression of PRL-related genes. Crossbred gilts were injected s.c. twice daily with saline (CTRL; n = 13), 2 mg of rpPRL (4PRL; n = 13), or 4 mg of rpPRL (8PRL; n = 13) in a 2.0-mL volume for a period of 29 d, starting at 75.1 +/- 0.5 kg BW. Jugular blood samples were collected before the first injection, as well as 14 and 28 d later, and were assayed for PRL, IGF-I, and leptin. Gilts were slaughtered on d 29 of treatment, and mammary glands were collected for dissection of parenchymal and extraparenchymal tissues, and for determination of parenchymal DNA, DM, protein, and fat contents. Levels of mRNA for PRL, PRL receptor (PRL-R), and signal transducers and activators of transcription (STAT5A and STAT5B) were determined via real-time PCR in the mammary parenchyma, as well as levels for PRL and PRL-R in the pituitaries. Treatments did not alter plasma (P = 0.48) IGF-I. Serum concentrations of PRL at slaughter were greater (P < 0.01) in both 4PRL and 8PRL compared with CTRL, whereas at mid-treatment, they were greater (P < 0.05) only in 8PRL gilts. Parenchymal tissue weight and parenchymal DNA concentrations increased with exogenous rpPRL (P < 0.001). The percentage of protein in parenchyma increased (P < 0.001), whereas that of DM (P < 0.001), fat (P < 0.001), and the protein:DNA ratio (P < 0.05) decreased with exogenous rpPRL. Treatment differences were always observed between the 4 mg dose and CTRL, and no further differences were noted when the dose was increased to 8 mg daily. Expression levels of PRL, but not PRL-R, were decreased (P < 0.05) in anterior pituitary glands and mammary glands of treated gilts. The mRNA levels of STAT5A and STAT5B increased (P < 0.05) with exogenous rpPRL. It is evident from these data that rpPRL can stimulate mammogenesis in prepubertal gilts through hyperplasia and increased expression of PRL-related genes.

Animals↗

PubMed2004

Impacts of dietary protein level and feed restriction during prepuberty on mammogenesis in gilts.

The possible roles of dietary protein level and feed restriction in regulating mammary development of prepubertal gilts were investigated. Cross-bred gilts were fed a commercial diet until 90 d of age and then divided into four nutritional regimens based on two pelleted diets (as-fed basis): a high-protein diet (HP = 13.8 MJ of ME, 1.0% total lysine, 18.7% CP) and a low-protein diet (LP = 13.8 MJ of ME, 0.7% total lysine, 14.4% CP). Nutritional regimens were as follows: 1) HP ad libitum until slaughter (n = 22, T1); 2) HP ad libitum until 150 d of age followed by LP until slaughter (n = 20, T2); 3) LP ad libitum until slaughter (n = 21, T3); and 4) HP with a 20% feed restriction until slaughter (n = 19, T4). Gilts were weighed, their backfat thickness was measured, and jugular blood samples were obtained on d 90, 150, and at slaughter to determine concentrations of prolactin, IGF-I, leptin, and glucose. Gilts were slaughtered 8+/-1 d after their first or second estrus (202.7+/-14.5 d of age). Mammary glands were excised, parenchymal and extraparenchymal tissues were dissected, and composition of parenchymal tissue (protein, fat, DM, DNA, protein/DNA) was determined. The T4 gilts weighed less (P < 0.01) and had less backfat (P < 0.01) than did gilts on other treatments on d 150 and at slaughter. Treatments had no significant effects on prolactin, IGF-I, or glucose concentrations, but there was a treatment x day interaction (P < 0.01) for leptin, with concentrations being lower at slaughter in restricted-fed (T4) vs. LP (T3) gilts (P < 0.05). There was less extraparenchymal mammary tissue (P < 0.01) in T4 gilts than in gilts from the other groups and a tendency (P = 0.13) for the amount of parenchymal tissue to be lower in T4 gilts. In conclusion, a lower lysine intake during prepuberty did not hinder mammary development of gilts, but a 20% feed restriction decreased mass of parenchymal and extraparenchymal tissues. The effect of feed restriction on extraparenchymal tissue is most likely associated with the lower fat deposition.

Adipose Tissue↗

PubMed2004

Effect of lead exposure on spatial learning and running speed in the short-tailed opossum, Monodelphis domestica (Didelphidae).

Studies were conducted to assess the spatial learning ability in adult males of the short-tailed opossum, Monodelphis domestica using a T-maze, complex maze and elevated radial 8-arm maze. This is the first study of maze learning in opossums. In the T-maze, the performance of these animals improved over an 8-day training period. Eighty percent of the subjects initially trained to turn to the right for food reinforcement reached criterion (80% correct responses) by day 3 and all reached criterion by day 4. Reversal training (subjects then trained to turn to the left) was more difficult and required 8 days for all subjects to reach criterion. In the complex maze, 89% of the animals achieved the criterion level of performance (3 consecutive trials with 5 or fewer errors) on the eighth day of training and all reached criterion by day 10. The relative importance of intramaze vs. extramaze cues in directing choice behavior was investigated in the radial arm maze. A discrimination procedure was used which selectively rewarded subjects for following only one set of cues. Animals in the intramaze group obtained a food pellet from a cup at the end of each arm. In the extramaze group, the food cups were placed on a small platform just beyond the end of each arm. All subjects were initially trained to visit each arm with the maze in a fixed position (controls) and did so within 15 test sessions. Following these initial trials, the maze was rotated to a different position after each choice. For subjects in the intramaze group, the food moved in conjunction with the rotation of the arms thereby increasing the relevance of intramaze cues. In the extramaze group, extramaze cues became more important because the food remained on the platforms in the same position in the room. Animals in the extramaze group performed significantly better than chance whereas the intramaze subjects did not. This indicates that intramaze cues are not as important as extramaze cues for accurate choice behavior in this marsupial. In addition, animals injected with tetraethyllead showed a significant impairment in running speed and T-maze learning ability as compared to saline-injected controls.

Animals↗

PubMed2003

Specific window of prolactin inhibition in late gestation decreases mammary parenchymal tissue development in gilts.

Prolactin is required from d 70 to 110 of gestation for normal mammary development of gilts. The goal of the present study was to determine the effect of inhibiting prolactin with bromocriptine during specific time windows during the second half of gestation on mammary gland development in gilts. Crossbred primigravid gilts were assigned as controls (n = 12) or received 10 mg of bromocriptine orally three times daily from d 50 to 69 (BR50, n = 12), d 70 to 89 (BR70, n = 12), or d 90 to 109 (BR90, n = 12) of gestation. Jugular blood samples were collected on d 50, 70, 90, and 109 of gestation and assayed for prolactin and estradiol. Gilts were slaughtered on d 109 of gestation and fetuses were counted and weighed. One row of mammary glands was used for dissection of parenchymal and extraparenchymal tissues, and for biochemical analyses. Tissue from the other row was used for measures of prolactin receptor number and affinity. Concentrations of prolactin were decreased markedly (P < 0.001) at the end of each bromocriptine treatment period compared with controls, but there was no overall treatment effect (P > 0.1) on estradiol concentrations. Extraparenchymal tissue weight of the mammary glands was unaffected by treatments (P > 0.1), but weight of parenchymal tissue, total DNA, and total RNA were lower (P < 0.01) in BR90 than control gilts. The percentage of DM in parenchymal tissue was unaffected by treatments (P > 0.1), but percentage of fat was higher and percentage of protein lower (P < 0.01) in BR90 gilts compared with controls. Cell size, as estimated by the protein:DNA ratio, also was lower (P < 0.01) in the BR90 group. Number and affinity of prolactin receptors in parenchymal tissue were not significantly altered by treatments. In conclusion, there is a specific time period in the second half of gestation, from 90 to 109 d, during which prolactin is essential for normal mammary parenchymal tissue development.

Animals↗

PubMed2003

These studies were conducted to assess the effects of lead toxicity on exploratory behavior and running. Effects of lead on exploratory behavior and running speed in the shrew, Blarina brevicauda (Insectivora).

These studies were conducted to assess the effects of lead toxicity on exploratory behavior and running speed in the short-tailed shrew, Blarina brevicauda. Shrews from the experimental group received 25 mg/kg/day of lead acetate in their drinking water for a period of 90 days. Control subjects received sodium acetate. Exploratory behavior was determined using a computerized activity chamber where movements of test subjects broke infrared beams projected onto the floor of the apparatus. Time spent (sec) in exploration was recorded over eight 6-min intervals. Running speed (km/hr) was measured in a microprocessor-controlled rectangular racetrack fitted with photocell timers. With respect to time spent in exploration, there were significant differences between lead-exposed (20.5-23.9 sec per 6-min testing session) and control subjects (6.8-8.1 sec) after the sixth testing interval in the activity chamber. With respect to maximal running speed, control subjects ran significantly faster (mean: 14.8 km/hr) than their lead-exposed counterparts (5.83 km/hr). Lead-exposed animals exhibited hyperactivity and increased random locomotor movements. They would frequently bump into the walls and their movements were more random. Controls typically ran along the racetrack in a straight line. These results represent the first data for the effects of lead exposure on exploratory behavior and running speed for shrews.

Animals↗

PubMed2002

Huntington's disease: a randomized, controlled trial using the NMDA-antagonist amantadine.

OBJECTIVE: To examine the acute effects of the NMDA receptor antagonist amantadine on motor and cognitive function in Huntington's disease (HD). BACKGROUND: Chorea in HD and in the levodopa-induced dyskinesias of PD may be clinically indistinguishable. In PD, hyperphosphorylation of NMDA receptors expressed on striatal medium spiny neurons contributes to peak-dose dyskinesias, and drugs that block these receptors can diminish chorea severity. Because these spiny neurons are the primary target of the neurodegenerative process in HD, sensitization of NMDA receptors on residual striatal neurons might also participate in the generation of motor dysfunction in HD. METHODS: To evaluate this possibility, 24 patients with HD entered a double-blind placebo-controlled crossover study of amantadine with two 2-week arms. RESULTS: Chorea scores were lower with amantadine (usually 400 mg/d) than placebo, with a median reduction in extremity chorea at rest of 36% (p = 0.04) for all 22 evaluable patients and of 56% in the 10 individuals with the highest plasma drug levels. Improvement correlated with plasma amantadine concentrations (p = 0.01) but not CAG repeat length. Parkinsonian rating scores did not worsen and there was no consistent change in cognitive measures. Adverse event profile was benign. CONCLUSIONS: Results suggest that NMDA receptor supersensitivity may contribute to the clinical expression of choreiform dyskinesias in HD and that selective antagonists at that site can safely confer palliative benefit.

Adult↗

PubMed2001

Evidence of a limited role for prolactin in the preparturient activity of confined gilts.

To investigate the role of peripheral prolactin in stimulating the preparturient activity of pigs, 12 cross-bred gilts housed in standard farrowing crates either received orally 10mg of bromocriptine three times per day from day 110 of gestation or served as controls. Jugular blood samples were collected on days 107 and 113 and assayed for prolactin, while the gilts' behaviour was recorded during the last 24h before parturition. Bromocriptine eliminated the preparturient rise in prolactin concentrations (P=0.002). As parturition approached all gilts initially spent less time laying down and more time standing or sitting. The frequency of posture changes also increased as did the incidence of oro-nasal behaviours. These trends were reversed during the final 5-8h before parturition, when the gilts began to lay down for longer periods. The mean concentrations of prolactin on day 113 were correlated with the frequency of posture changes (r=0.70,P=0.015) but not with any other behavioural measure (P>0.10). Bromocriptine had no overall effect on any of the preparturient behaviours (P>0.10) but did reduce the frequency of posture changes 13-16h before parturition (P=0.05). There was a significant interaction between time until parturition and bromocriptine treatment for time spent lying down (P=0.013): bromocriptine delayed the time when the gilts began lying down again as parturition approached. The results suggest that peripheral prolactin plays only a limited role in the preparturient activity of pigs and throws some doubt on its importance in the motivation of nest building in this species.

Journal Article↗

PubMed2001

Anti-beta 2 glycoprotein 1 and anti-annexin V antibodies in women with recurrent miscarriage.

While it has been established that anti-phospholipid antibodies (aPL) are associated with recurrent miscarriage (RM), the importance of anti-beta2 glycoprotein 1 (GP1) IgG and anti-annexin V IgG antibodies as risk factors for RM is undefined. We have investigated the prevalence of anti-beta2 GP1 IgG and anti-annexin V IgG antibodies in 54 aPL-positive and 48 aPL-negative women with RM. The prevalence of IgG anti-beta2 GP1 antibodies was not significantly different in persistently aPL-positive women with RM (7%), aPL-negative women with RM (6%) and the normal parous control group (3%). Anti-annexin V IgG antibody prevalence was significantly increased in aPL-positive women with RM compared with aPL-negative women with RM (P = 0.01). The elevations were found in 35%, 19% and 16% of aPL-positive women with RM, aPL-negative women with RM and the control group respectively. No women showed positivity for both anti-beta2 GP1 IgG and anti-annexin V antibodies. Anti-beta2 GP1 IgG antibodies do not appear to be contributory to the investigation of women with RM. Anti-annexin V antibody positivity, although associated with aPL positivity in women with RM, is not an independent risk marker.

Abortion, Habitual↗

PubMed2001

A brief analysis of clinical pharmacy interventions undertaken in an Australian teaching hospital.

Selected clinical pharmacy interventions undertaken during a 30-day data capture period were analysed, seeking to gain a greater understanding of the nature of the drug-related problems involved. Pharmacists were asked to record only interventions that were of potentially major significance. A total of 67 interventions were submitted for analysis. In 28 cases (41.7% of the initial total) the intervention reports were excluded from further analysis after initial review. For the remaining 39 interventions, 20 patients (51%) were under the care of a medical unit, and cardiovascular/antithrombotic agents accounted for 17 reports (43.5%). The majority of interventions were implemented at the time of inpatient medication order review by the clinical pharmacist (n=25, 64%). The most common category of drug-related problem addressed in the interventions related to the prescription of inappropriately high doses of the correct drug for the patient (n=17, 43.6%). Deficiencies in technical knowledge accounted for less than 25% of all cases.

Aged↗

PubMed2001

The use of pigs as an animal model to evaluate the efficacy, potency and specificity of two growth hormone releasing factor analogues.

In 1982, Guillemin et al reported the isolation of the human (h) growth hormone (GH) releasing factor (GRF) from a pancreatic tumour in an acromegalic patient. Since then, work to develop potent GRF analogues has been widespread and the rat has been the main animal model used. The aim of the present study was to compare the efficacy, potency and specificity of two GRF analogues with those of the native GRF(1-29)NH(2)using pig (p) as the animal model. Two analogues, Al ([His(1), D-Ala(2), Ala(8,9,15,17), D-Arg(29)] hGRF(1-29)NH(2)) and A2 ([D-Ala(2), Ala(8,9,15,17), D-Arg(29)] hGRF(1-29)NH(2)) were compared with the h or pGRF(1-29)NH(2). Five studies were designed using 28-48 kg BW growing barrows. Results showed that the two GRF analogues were more potent than the native GRF molecule, were highly specific, were active for long periods of time and were able to induce changes in body composition similar to those reported with GH or other GRF analogues. Because of the similarity between swine and human species with respect to the amino acid sequence of GRF and to the physiology, secretion and effects of GH, it can be proposed that the pig could be used as a pre-clinical animal model to study and test new GRF molecules over short and long periods of time.

Animals↗

PubMed2001

Renal failure in patients with neurogenic lower urinary tract dysfunction.

People with multiple sclerosis, paraplegia and neural tube defects typically have neurogenic lower urinary tract dysfunction (NLUTD). This encompasses detrusor hyperreflexia with or without detrusor sphincter dyssynergia and hypo- or acontractility. Their effects undermine safe, effective and controlled storage and voiding of urine and predispose to reflux nephropathy. Therefore, patients in these diagnostic groups with NLUTD would be expected to have increased risk of renal failure. The aim of this study was to quantify this risk using the General Practice Research Database (GPRD). All patients registered in the database between 1994 and 1997 and aged 10-69 were included in the study. The prevalence and incidence of renal failure and renal replacement therapy in the general population was ascertained, as was the prevalence of multiple sclerosis, paraplegia and neural tube defects. The prevalence of renal failure in each of the special populations was then compared with the prevalence in the unaffected general population. The age-standardised prevalence of renal failure in the GPRD population aged 10-69 years was 14 per 10,000. The rate ratio of renal failure compared with the general population in each of the years 1994-1997 for neural tube defects ranged between males (M) 6.8-9.0 and females (F) 9.2-11.5, for paraplegia M 4.1-9.0, F 4.0-7.0, and for multiple sclerosis M 0.4-1.3, F 0.5-2.2. As expected, people with paraplegia or neural tube defects were found to have a substantially increased risk of renal failure compared with the general population. We could not demonstrate an increased risk of renal failure in people with multiple sclerosis. We believe this finding requires further study, but may reflect a problem in the recognition of renal failure in this group of patients. We recommend that all three patient groups should be regularly screened so that renal impairment may be detected prior to the development of renal failure.

Adolescent↗

PubMed2000

The effect of intake level on whole body kinetics and hepatic removal of somatotropin in growing beef steers.

The effect of level of intake of a high concentrate diet (0.6, 1.0 and 1.6 x maintenance requirements, M) on whole body somatotropin (St) kinetics was evaluated in six growing, multicatheterized beef steers (398+/-27 kg), using a double 3x3 Latin Square design with 21 d-periods. Simultaneously to St kinetics, net hepatic removal of St was measured in 4 of the 6 steers. On the last day of each period, concentrations and net fluxes of St were determined, first in basal conditions for 5 hr, and then, during a primed (0.5 mg of St) infusion of bovine St (1.5 mg/hr) administered for 3 hr. The following results are LSM +/- SEM for 0.6, 1.0, and 1.6 x M, respectively. Increasing feed intake linearly decreased (P<0.01) basal St concentrations (5.6, 4.6, 3.1+/-0.62 ng/ml), mainly through a linear increment (P<0.01) in the metabolic clearance rate (32.7, 37.1, 43.4+/-2.60 l/hr), although secretion rate also tended to decrease (P = 0.09; 189, 185, 135+/-27.2 microg/hr). During the infusion period, net liver removal of immunoreactive ST averaged 60% of the total inflow of St. This confirms the liver is capable of removing large amounts of St, suggesting it has an important role in metabolic clearance of the hormone. Net liver removal of St, however, was not affected by intake. There was a strong correlation between the metabolic clearance rate of St with either whole body protein synthesis (r = 0.75, P<0.01) or protein retention (r = 0.68, P<0.01). Together these results indicate the importance of postsecretory metabolism of St in determining both arterial plasma concentrations of St and whole body protein anabolism.

Animal Feed↗

PubMed2000

Mammary gland development and hormone levels in pregnant Upton-Meishan and large white gilts.

Genetic differences between Upton-Meishan (UM, n = 13) and Large White (LW, n = 14) gilts were studied with regard to mammary gland development and concentrations of hormones. Gilts were weighed and their backfat measured at mating, and at d 70 and 109 of gestation. Jugular blood samples were also collected at these times and assayed for prolactin, cortisol, IGF-I, insulin, glucose, progesterone, and estradiol. Gilts were slaughtered on d 110 of gestation. One row of mammary glands was used for dissection and biochemical analyses. The other row was used for determination of prolactin receptor number and affinity. UM gilts weighed less (P<0.05) and had more backfat (P<0.01) than LW gilts at all times. Parenchymal tissue weight was less (P<0.05) in UM gilts. Percent fat (P<0.001) and dry matter (P<0.001) in parenchymal tissue were greater in UM gilts while that of protein (P<0.001) was lower. Total protein weight in parenchyma was also lower in parenchyma was also lower in UM gilts (P = 0.01). Both DNA (P<0.001) and RNA (P<0.001) contents were lower in UM gilts while RNA/DNA remained similar (P>0.1). Number of prolactin receptors were lower (P = 0.06) and affinity greater (P<0.05) in UM gilts. Cortisol levels were greater (P<0.01) in UM gilts while other hormones were not affected (P> 0.1). Results clearly demonstrate genetic differences with regard to mammogenesis in gilts and suggest that the less mammary gland development in Upton-Meishan compared with Large White breed of gilts may be related to lower number of prolactin receptors.

Animals↗

PubMed2000

A UK general practice database study of prevalence and mortality of people with neural tube defects.

OBJECTIVE: To investigate the prevalence of neural tube defects (NTDs) in the UK and to compare the mortality rate with that of the general population. METHODS: A cross-sectional study. The General Practice Research Database (GPRD) contains the prescribing and diagnostic records since 1990 of over 4 million people from throughout the UK. All patients aged 10-69 and registered on the database in the years 1994-1997 were included in the study. Patients with a diagnosis of NTD were identified from the database and prevalence and standardized mortality ratios in each year were calculated. RESULTS: The size of the GPRD reduced during the study period - there were 2116452 patients aged 10-69 years on the database in 1994, of whom 1751 had a prior record of NTD. In 1997 there were 998368 patients, of whom 842 had an NTD. The age standardized prevalence between 1994 and 1997 for NTDs ranged between 7.8 and 8.4 per 10000 for males and 9.0 and 9.4 per 10000 for females aged 10-69 years. There were 27 deaths in patients with a record of NTD over the four-year study period. The standardized mortality ratio for the years 1994 to 1997 for NTDs ranged between 1.9 and 2.9. CONCLUSIONS: These data give an estimate of the prevalence of NTDs in the general population. They also show that those who have survived to age 10 years still have double the mortality of the general population.

Adolescent↗

PubMed2000

The effect of feed intake level on splanchnic metabolism in growing beef steers.

The effect of feed intake level (.6, 1.0, and 1.6 x maintenance energy and protein requirements, M) on splanchnic (portal-drained viscera [PDV] plus liver) metabolism was evaluated in six multicatheterized beef steers (398 +/- 27 kg), using a double 3 x 3 Latin square design. On the last day of each 21-d experimental period, six hourly blood samples were collected from arterial, portal, and hepatic vessels. Due to catheter patency, PDV fluxes were measured on five steers, and liver and splanchnic fluxes on four steers. Increasing intake elevated (P < .01) splanchnic release of total (T) amino acids (AA), through increases (P < .01) in PDV release of both essential (E) and nonessential (NE) AA, in spite of a tendency (P < .20) for increased liver removal of NEAA. The PDV release of AA N represented 27 and 51% of digested N for 1.0 and 1.6 x M, respectively. At 1.0 and 1.6 x M, the liver removed 34% of total AA released by the PDV. For individual AA, portal flux of most EAA increased (P < .05) with feed intake, and the increase (P < .10) in splanchnic flux was accompanied by increased arterial concentration for all EAA except histidine, lysine, and methionine. This suggests that these might be limiting AA for this diet. On a net basis, most individual NEAA were released by the PDV except glutamate and glutamine, which were removed by the digestive tract. There was a net removal of NEAA by the liver, except for aspartate and especially glutamate, which were released. Ammonia release by the PDV tended (P < .20) to increase with intake and represented 69, 53, and 45% of digested N at .6, 1.0, and 1.6 x M, respectively. Urea removed by the PDV, unaffected by intake, represented 32, 33, and 21% of the digested N. Arterial glucose concentration increased linearly (P < .01) with greater intake, whereas net liver and splanchnic glucose release increased in a quadratic (P < .05) manner. Net PDV glucose release represented 26% of net glucose hepatic release at 1.6 x M. Intake elevated (P < .10) both insulin and glucagon arterial concentrations, resulting from a larger increment of portal release (P < .01) than hepatic removal (P < .05). Intake-based variations in IGF-I and NEFA arterial concentrations (P < .05) were not related to changes in splanchnic metabolism. These results clearly show the crucial role of the splanchnic tissues in regulating the profile and quantity of AA and concentrations of glucose and pancreatic hormones reaching peripheral tissues.

Amino Acids↗

PubMed2000

Inhibition of prolactin in the last trimester of gestation decreases mammary gland development in gilts.

Prolactin is required for mammary development in various species but its possible role for mammogenesis in pigs is not known. The goal of the present study was therefore to determine the effect of prolactin inhibition by bromocriptine during the last third of gestation on mammary gland development in gilts. Twenty-eight primigravid gilts were assigned as controls (n = 15) or received 10 mg of bromocriptine orally thrice daily (n = 13) from d 70 to 110 of gestation. Jugular blood samples were collected on d 70 of gestation and every 8 d thereafter and were assayed for prolactin, IGF-I, estradiol, and progesterone. Gilts were slaughtered on d 110 of gestation and fetuses were counted and weighed. One row of mammary glands was used for dissection of parenchymal and extraparenchymal tissues and for determination of DNA, RNA, dry matter, protein, and fat contents. Tissue from the other row was used for measures of prolactin receptor number and affinity. Concentrations of prolactin were drastically reduced throughout the bromocriptine treatment period (P < .001), whereas there was no overall treatment effect on progesterone and IGF-I levels (P > .10). Total weight and extraparenchymal tissue weight of the mammary glands were unaffected by treatment (P > or = .1), but weight of parenchymal tissue, total DNA, and total RNA decreased (P < .01) with bromocriptine treatment. Percentages of fat and dry matter in parenchymal tissue increased with bromocriptine treatment (P < .01) and the percentage of protein decreased (P < .01). Number of prolactin receptors in parenchymal tissue decreased with bromocriptine treatment (P < .001) and receptor affinity increased (P < .001). Average fetal weight was lower in gilts receiving bromocriptine than in control gilts (P = .05), but fetal number did not differ (P > .1). These results clearly demonstrate that prolactin is essential for normal mammary gland development and can affect fetal growth during the last third of gestation in gilts.

Animals↗

PubMed1999

Administering exogenous porcine prolactin to lactating sows: milk yield, mammary gland composition, and endocrine and behavioral responses.

Third-parity sows received s.c. injections of sterile water (CTL, n = 12) or 15 mg of recombinant porcine prolactin (pPRL, n = 12) at 0730, 1530, and 2330 from d 2 to 23 of lactation. Litters were standardized to 11 or 12 pigs and were weighed weekly until weaning (d 24). On d 22 of lactation, milk production was estimated, and a milk sample was obtained the next day. Jugular blood samples were collected from sows on d 2, 7, 14, and 21 of lactation. Sows were slaughtered and mammary glands collected at d 24. Injections of pPRL doubled the serum concentrations of prolactin (P < .001) on d 7, 14, and 21 of lactation and decreased IGF-I concentrations on d 14 (P = .07) and 21 (P < .01). Weight, backfat, and milk yield of sows and mean pig weights were not affected by pPRL (P > . 1), yet the mean duration of intervals between nursings was reduced by 4.2 min (P = .06) in pPRL litters (45.9 vs 41.7 min). Dry matter and fat percentages in milk were lower in pPRL sows (P < .01). Weights of parenchymal and extraparenchymal tissues were not altered by pPRL treatment (P > .1). Number of prolactin receptors in parenchymal tissue as well as receptor affinity were similar in both groups (P > .1). Results indicate that virtually all prolactin receptors were saturated in CTL sows. This is probably the reason why additional exogenous prolactin had negligible effects.

Animals↗

PubMed1999

The effect of intake on protein metabolism across splanchnic tissues in growing beef steers.

The contribution of the total splanchnic tissue (TSP; portal-drained viscera (PDV) plus liver) to whole-body protein metabolism was estimated in relation to intake (0.6, 1.0 and 1.6 x maintenance requirements), in six multicatheterized growing beef steers used in a double 3 x 3 Latin square design. At the end of each 21 d experimental period, [1-13C]leucine was infused into a jugular vein (1.05 mmol/h for 5 h, preceded by a priming dose of 1.05 mmol). Arterial, portal and hepatic blood samples were collected hourly during the infusion. The increment in TSP leucine irreversible loss rate (ILR) observed with increasing intake reached significance (P < 0.10) only for PDV, while whole-body ILR increased markedly (P < 0.001) with intake. The relative contribution of TSP to whole-body leucine ILR averaged 44% (25% from PDV and 19% from the liver). Although these proportions were not affected by intake, on an incremental basis more than 70% of the increase of whole-body leucine ILR between the 0.6 and 1.0 x maintenance originated from the changes in TSP ILR, while the corresponding value was below 13% between 1.0 and 1.6 x maintenance. Total whole-body leucine oxidation and fractional oxidation increased (P < 0.05) with intake. Protein retention increased with intake (P < 0.01), as a result of a greater increase in protein synthesis compared with protein degradation. Protein breakdown had a major impact on protein turnover as 65% of the protein synthesized was degraded when intake varied from 1.0 to 1.6 x maintenance. Net leucine portal absorption increased (P < 0.001) with intake and represented 1, 16 and 23% of whole body leucine ILR, for 0.6, 1.0 and 1.6 x maintenance, respectively. Although leucine oxidation was not a major component of whole body ILR (9.3-19.9%), it represented 69% of the net available leucine (portal absorption) even at 1.6 x maintenance. The lower relative contribution of the TSP to whole-body leucine ILR at higher intake indicates the proportional increase in the metabolic activity of peripheral tissues as the animals moved into positive protein balance.

Analysis of Variance↗