Biomedical subjects

D N Foster

Publications and source records attributed to D N Foster.

At least 37 records · Page 2Linked to original sources

PubMed1999

Expression of HAND gene products may be sufficient for the differentiation of avian neural crest-derived cells into catecholaminergic neurons in culture.

Members of the basic helix-loop-helix family of DNA binding proteins have important roles in the development of subpopulations of neural crest-derived neurons. We have cloned the chicken homologues of dHAND (HAND2) and eHAND (HAND1), basic helix-loop-helix DNA binding proteins whose neuronal expression is restricted to sympathetic and enteric neural crest-derived ganglia. Transcripts encoding dHAND and eHAND are expressed in sympathetic ganglia beginning at Hamburger and Hamilton stage 17-18. Antisense blockade of transcripts encoding HAND genes in neural crest-derived cells in vitro results in a significant reduction in neurogenesis. Differentiation of catecholaminergic neurons is also reduced by 52% if the expression of transcripts encoding dHAND and eHAND is reduced using antisense oligonucleotide blockade. The effect on neurogenesis and phenotypic expression of neural crest-derived neurons is specific; blockade of HAND gene expression has no apparent influence on the differentiation in vitro of neural tube-derived neurons. Use of a replication-competent avian retrovirus to constitutively express HAND genes in neural crest-derived cells in vitro, under nonpermissive growth conditions in medium supplemented with 2% chick embryo extract (CEE), induced precocious catecholaminergic differentiation. Constitutive expression of HAND gene products resulted in a significant increase in catecholaminergic differentiation of cells grown in medium supplemented with 10% CEE, a permissive growth condition for catecholaminergic development. These results suggest that the expression by neural crest cells of dHAND and eHAND may be both sufficient and necessary for catecholaminergic phenotypic expression.

Animals↗

PubMed1999

Molecular cloning and tissue distribution of an avian D2 dopamine receptor mRNA from the domestic turkey (Maleagris gallopavo).

The reverse transcriptase-polymerase chain reaction (RT-PCR), in combination with 5' and 3' rapid amplification of cDNA ends (RACE), was used to clone a G protein-coupled receptor from turkey brain mRNA. This cDNA clone has an open reading frame of 1,311 base pairs encoding a 436-residue protein with seven transmembrane-spanning domains and exhibits high homology with previously cloned mammalian D2 dopamine receptors. Northern blot analysis of turkey brain mRNA detected an approximate 2.4-kb transcript. RT-PCR and subsequent nucleotide sequence analysis of turkey brain and peripheral tissue mRNA also demonstrated the presence of an alternatively spliced mRNA corresponding to the predicted D2 short isoform. RT-PCR experiments demonstrated a widespread distribution of alternatively spliced D2 dopamine receptor transcripts throughout the turkey brain and in select peripheral tissues as well. In situ hybridization experiments detected strong autoradiographic signals over much of the turkey telencephalon, diencephalon, mesencephalon, cerebellum, pituitary, and pineal gland. Dopamine has several important functions as a neurotransmitter and hormone in mammals and may have similar actions in avian species. The cloning and tissue distribution of the D2 receptor subtype should enable the investigation of any functional role dopamine and dopamine receptors exert on the physiology and behavior of birds.

Amino Acid Sequence↗

PubMed1999

Association of specific DNA binding and transcriptional repression with the transforming and myogenic activities of c-Ski.

The ski oncogene encodes a transcription factor that induces both transformation and muscle differentiation in avian fibroblasts. The first 304 amino acids of chicken Ski, the transformation domain, are both necessary and sufficient to mediate these biological activities. Ski's biological duality is mirrored by its transcriptional activities: it coactivates or corepresses transcription depending on its interactions with other transcription factors. Ski represses transcription through specific binding to GTCTAGAC (GTCT element) but it possesses a transferable repression activity that can function independently of this DNA element. In this study, we locate this repression domain to the NH2-terminal two-thirds and the GTCT binding region to the COOH-terminal one-third of Ski's transformation domain. Mutations in the transformation domain of c-Ski reveal a strong correlation between GTCT-mediated transcriptional repression and the biological activities of transformation and myogenesis. We also show that a dimerization domain located at the COOH terminal end of the Ski protein increases its transforming activity and its binding to GTCTAGAC.

Animals↗

PubMed1998

Molecular cloning and characterization of a highly conserved chicken cellular nucleic acid binding protein cDNA.

A chicken cellular nucleic acid binding protein (cCNBP) cDNA was isolated from a chicken Con-A-stimulated immune cell library by differential screening. cCNBP is a Cys/Cys-His/Cys zinc finger DNA binding protein of unknown function. The chicken CNBP nucleotide and deduced amino acid sequence showed extraordinary sequence conservation (between 81-98% similarities) when compared to human, mouse and rat CNBP. The CNBP gene was shown to be a single copy and to cross-hybridize to human and mouse genomic DNA. A Northern blot analysis revealed cCNBP to be a constitutively expressed gene in a wide variety of tissues and to be differentially expressed in cultured chicken spleen and bursal cells after mitogen stimulation.

Animals↗

PubMed1998

The DF-1 chicken fibroblast cell line: transformation induced by diverse oncogenes and cell death resulting from infection by avian leukosis viruses.

DF-1 is a continuous cell line of chicken embryo fibroblasts. The cells are free of endogenous sequences related to avian sarcoma and leukosis viruses and have normal fibroblastic morphology. DF-1 cells support the replication of avian retroviruses; diverse oncogenes induce foci of oncogenic transformation on monolayers of DF-1, and avian leukosis viruses of envelope subgroups B, D, and C induce cell death and form plaques. The new cell line will greatly facilitate studies on oncogenic transformation and cell killing by avian viruses.

Animals↗

PubMed1998

The EV-O-derived cell line DF-1 supports the efficient replication of avian leukosis-sarcoma viruses and vectors.

The lack of a well-behaved permanent, adherent, nontransformed chicken cell line has made some experiments with avian leukosis-sarcoma viruses (ASLV) and vectors considerably more difficult. The EV-O-derived line, DF-1, supports the efficient replication of subgroups (A), (B), and (C) ASLV, as well as amphotrophic murine leukemia virus and an ASLV-derived vector that has its env gene derived from the env gene from an amphotrophic murine leukemia virus. The cell line responds appropriately to the expression of a transforming oncogene (v-myc) to a growth suppressor gene [p21(waf1)] and can be sorted (using FACS) if infected by an ASLV vector that expresses GFP.

Alpharetrovirus↗

PubMed1998

Quantification of full-range-of-motion unilateral and bilateral knee flexion and extension torque ratios.

OBJECTIVES: To evaluate the reliability and variability of repeated measurements of isometric knee flexion and extension strength, to quantify the extent of measurement error that may occur due to gravity, and to quantify isometric knee flexion/extension torque ratios at multiple angles through a full range of motion. DESIGN: Reliability assessment. SETTING: A university exercise center. PARTICIPANTS: Seventy-seven healthy men and women recruited from a university and surrounding community. INTERVENTION: Isometric knee flexion and extension strength tests. MAIN OUTCOME MEASURES: Knee flexion/extension strength was measured at 6 degrees, 24 degrees, 42 degrees, 60 degrees, 78 degrees, 96 degrees, and 108 of knee flexion. Before each contraction, subjects were instructed to completely relax the limbs to measure the mass of the lower leg. Torque values obtained during relaxation at each angle were added to or subtracted from "Total Torque" (TTQ) at peak exertion. The adjusted value was recorded as "Net Muscular Torque" (NMT). RESULTS: Reliability for the unilateral and bilateral tests was high (r =.88 to r=.98) and measurement variability low (SEM%=5.1% to 12.6%). There was a statistically significant difference at each angle of measurement between the TTQ and NMT values for both knee flexion and extension. Knee flexion/extension ratios were highly dependent on the angle tested, ranging from 1.30 (at 60) to .31 (at 1080). CONCLUSIONS: Isometric testing, using standardized angles, can reliably quantify knee flexion/extension strength. Furthermore, these findings emphasize the importance of correcting for the mass of the lower leg when assessing muscle function. Angle-specific knee flexion/extension torque ratios should provide clinicians with a more precise method of evaluating muscular balance (imbalance) throughout the range of motion.

Adolescent↗

PubMed1998

Vasoactive intestinal peptide stimulates turkey prolactin gene expression by increasing transcription rate and enhancing mRNA stability.

This study evaluates the transcriptional and post-transcriptional regulation of prolactin (PRL) by vasoactive intestinal peptide (VIP). Pituitary nuclei from laying (control), incubating (with enhanced VIP secretion), and VIP-immunized laying turkey hens, and from pituitary cells cultured with or without VIP were used in nuclear run-on transcription assays. Cytoplasmic PRL mRNA was analyzed by slot blot hybridization. PRL transcription was greater in hyperprolactinemic incubating birds (PRL/beta-actin=3.33) than in laying birds (PRL/beta-actin=1.83). VIP-immunoneutralized birds had 47% and 51% decreases in PRL transcription and cytoplasmic PRL mRNA, respectively when compared with laying birds. In primary pituitary cell cultures, VIP significantly increased the transcription rate of PRL (3.8-fold) and cytoplasmic PRL mRNA (3.2-fold) compared with that of non-VIP-treated pituitary cells. The stability of pre-existing PRL mRNA was measured by Northern blot analysis after addition of actinomycin D. PRL mRNA half-lives were calculated using a two-component model, with a first-long component of 18.0+/-1.0 h and a second-short component of 3.7+/-0.7 h in non-VIP-treated pituitary cells. Both half-lives were significantly increased (53. 2+/-6.9 and 26.3+/-4.3 h) in VIP-treated cells. The present data show that VIP acts to stimulate PRL expression by up-regulating the transcription rate of PRL and by enhancing PRL mRNA stability.

Animals↗

PubMed1998

Transient expression of clusterin (sulfated glycoprotein-2) during development of rat pancreas.

Clusterin has been known to play important roles not only in remodeling damaged tissues, but also in tissue reorganization during embryonic development. In the present study, we have investigated the expression of clusterin in the endocrine pancreas during embryonic development. Although a weak immunoreaction was detected in some pancreatic primordial cells at day 14 of gestation, distinct clusterin expression was identified by immunocytochemistry and Northern blot analysis at the 16th day of gestation. Clusterin-producing cells, which corresponded to insulin-containing cells, accounted for the major portion of the developing islet of Langerhans up to 18 days of gestation. Thereafter, clusterin-producing cells display similar distribution and morphological features to glucagon-producing cells. Clusterin expressed in the pancreas was shown by Western blot analysis to be a disulfide-linked heterodimer of 70 kDa with an alpha-subunit of 32 kDa. During early developmental stages, however, we found that proteolytic internal cleavage of the clusterin molecule occurred from the 18th day of gestation. Only one 70 kDa band on the 16th day and two bands (32 kDa and 70 kDa) on the 18th day of gestation were detected by Western blot analysis even in reducing conditions, while only a single 32 kDa band was detected on the second day after birth. The levels of clusterin mRNA in the pancreas transiently increased from the 16th day of gestation to the second day after birth, during the period when active cellular reorganization takes place to form the classic cellular features of the islet. Among various tissue (kidney, brain, liver, heart, lung and pancreas) the levels of clusterin mRNA were the highest in the pancreas from the 18th day of gestation to the second day after birth. In contrast, the lowest expression was observed in adult pancreatic tissue. The higher expression of clusterin in developing pancreas must indicate its involvement in tissue organization during development.

Animals↗

PubMed1997

Isometric torso rotation strength: effect of training frequency on its development.

OBJECTIVE: To examine training frequency's effect on torso rotation muscle strength. DESIGN: The study followed a pretest-posttest randomized-group design. SETTING: University laboratory. PATIENTS: Subjects, 33 men (age 30 +/- 11yr) and 25 women (age 28 +/- 10yr) with no history of low back pain, volunteered to participate in the study and were tested for isometric (IM) torso rotation strength before (T1) and after (T2) 12 weeks of training. Measurements of maximal voluntary IM torso rotation torque (N.m) were made through a 108 degrees range of motion (54 degrees, 36 degrees, 18 degrees, 0 degree, -18 degrees, -36 degrees, -54 degrees). Subjects were stratified by peak torque at T1, and randomized to a nonexercising control group (C, n = 10), or groups that trained once a week (1x/wk, n = 16), twice a week (2x/wk, n = 17), or three times a week (3x/wk, n = 15); and all groups were similar in strength. INTERVENTIONS: Training consisted of 8 to 12 repetitions of full range dynamic variable resistance exercise to volitional fatigue, for both left and right rotation. MAIN OUTCOME: To determine the best training frequency for the development of torso rotation strength. RESULTS: Relative improvements (average increase in strength gained at each angle) for the training groups were 4.9%, 16.3%, and 11.9% for the 1, 2, and 3x/wk groups, respectively. The 1x/wk group did not increase in IM torso rotation strength compared to the control group at any angle. Both the 2 and 3x/ wk groups increased their IM torso rotation strength compared to the control group at all but one angle. There were no significant differences in IM torso rotation strength between the groups that trained 2 or 3x/wk. During the training period, the 2 and 3x/wk groups increased their dynamic training load significantly more than the 1x/wk group. CONCLUSIONS: Posttraining dynamic strength was not different between training frequencies of 2 and 3x/wk. Therefore, training the rotary torso muscles 2x/wk is recommended.

Adult↗

PubMed1997

Baculovirus-mediated expression of chicken growth hormone.

A full-length chicken growth hormone (cGH) cDNA was placed downstream from the Autograph californica nuclear polyhedron virus, AcNPV, polyhedron gene promoter and expressed in Sf9 insect cells. Secreted recombinant cGH levels averaged 2-10 micrograms/ml from day 5-10 postinfection. The recombinant cGH analyzed by SDS-PAGE gels and Western blotting consisted of a doublet with M(r) of 26.5 and 23.5 kDa. Analysis by 2-D electrophoresis of partially-purified recombinant cGH and purified native cGH revealed similar immunoreactive charge isoforms and M(r) variants. The recombinant hormone was biologically active in a homologous radioreceptor assay. The results show that cGH expressed in insect cells is biologically and immunologically active, and that a variety of isoforms are secreted which exhibit size and charge properties similar to those of pituitary-derived cGH.

Animals↗

PubMed1997

Ornithine decarboxylase activity in muscle, liver, and intestinal tissue of turkeys during a short-term feed withdrawal and following refeeding.

The activity of ornithine decarboxylase (ODC), an enzyme associated with cellular growth and protein synthesis, was examined in breast muscle, liver, and intestinal tissues of turkeys during a short-term period of feed withdrawal (FW) and following refeeding. Turkeys from a randombred control line were reared under standard management practices to 3 wk of age in battery brooders. Feed was then withdrawn from FW birds for a 48-h period, after which feed was consumed ad libitum. Control birds consumed feed ad libitum throughout the test period. Tissues were collected from 12 birds per treatment following 24 and 48 h of FW and at 6, 12, 24, and 48 h following refeeding for later determination of tissue ODC activity. Activity of ODC was greater in tissue from the small intestine than in liver tissue and both had greater activity than that exhibited by breast muscle. Short-term FW and refeeding produced differential responses in ODC activity of the three tissues examined. Feed withdrawal resulted in a reduction of ODC activity in intestinal tissue, whereas activity was unaffected for liver or breast muscle tissues. Compensatory increases in ODC activity were observed in liver and intestinal tissues; however, the increase was both more rapid and transitory in small intestine than in liver tissue. The ODC activity in breast muscle was largely unaffected by short-term FW and refeeding. Patterns of ODC activity in liver during FW and refeeding closely resembled patterns observed for absolute and relative liver weight. Thus, the results of the present experiment demonstrate that short-term FW and refeeding influence underlying growth mechanisms of supply organs, such as hepatic and intestinal tissue, in addition to affecting overall growth and muscle development.

Analysis of Variance↗

PubMed1997

Nucleic acid concentrations and ornithine decarboxylase activity in tissues from three lines of turkeys.

Developmental patterns in turkeys of tissue ornithine decarboxylase (ODC) activity and nucleic acid concentrations were studied in a randombred control (RBC2), in a subline of RBC2 selected for increased 16-wk BW (F), and in a commercial sire line (C). Lines F and C were similar in BW, but Line C had greater breast weight than Line F. Lines F and C were heavier and had greater breast weights than the RBC2 population. Tissue ODC activity reached its highest level on Day 2 posthatch, declined rapidly through 13 d of age, and remained relatively low through 144 d of age. The ODC activity of liver tissue was greater than that of either breast or leg muscle. Line C had greater tissue ODC activity at 2 and 8 d of age than the RBC2 population, but Line F was not different from C or RBC2. There were no line differences for ODC activity at the other ages tested, resulting in a age by line interaction. The DNA content of muscle tissue was greatest at hatch and declined to baseline values by 55 d of age. The DNA content of breast muscle was higher than for leg muscle at hatch, but this pattern was reversed following Day 8. Muscle tissue from Lines F and C had a lower DNA content than that of the RBC2 population. Although the RNA content of muscle tissue was similar across lines, the RNA content of breast muscle was greater than for leg muscle during the early posthatch period just prior to the onset of rapid growth in this tissue. Results of the present experiment demonstrate changes in muscle functional cellularity during the growth phase in association with genetic increases in BW, but not breast muscle development. In contrast, tissue ODC activity was increased in association with genetic increases in breast muscle development, but not BW.

Aging↗

PubMed1997

Transcriptional and post-transcriptional regulation of prolactin during the turkey reproductive cycle.

The present study examined turkey prolactin (PRL) transcription and PRL mRNA stability during different reproductive stages. Nuclear run-on transcription assays were performed using isolated nuclei from pituitaries of turkeys at different reproductive stages. Meanwhile, cytoplasmic PRL mRNA and plasma PRL were measured by slot blot and RIA respectively. The PRL transcription, pituitary cytoplasmic PRL mRNA abundance and plasma PRL levels increased after photostimulation and peaked at the incubating stage (P < 0.05). A decrease in PRL transcription, pituitary cytoplasmic PRL mRNA and plasma PRL (P < 0.05) was observed during the transition from incubation to photorefractoriness. Nest-deprivation reduced circulating PRL (P < 0.05), whereas pituitary cytoplasmic PRL mRNA and PRL transcription were not significantly altered from those in incubating birds (P > 0.05). The half-life of PRL mRNA was determined in pituitaries of non-photostimulated, laying, incubating and photorefractory hens. Primary pituitary cell cultures were treated with the transcription inhibitor actinomycin-D and the decay of the pre-existing PRL mRNA was quantified using Northern blot analysis. The PRL mRNA half-life was 1.5- and 1.4-fold greater in incubating and laying birds respectively than in non-photostimulated turkeys (P < 0.05). The half-life of PRL mRNA in photorefractory and incubating hens was similar in spite of great differences in pituitary PRL mRNA steady-state levels and PRL transcription. Our data suggest that photoinduced changes in pituitary PRL mRNA and plasma PRL are due to changes in both PRL transcription and PRL mRNA stability. Nest-deprivation inhibits the PRL releasing mechanism(s) independently of PRL transcription in turkeys.

Animals↗

PubMed1996

Differentiation of smooth muscle phenotypes in mouse mesangial cells.

Smooth muscle alpha-actin (SMA) mRNA, a marker of vascular smooth muscle cells, was identified in the normal glomerular mesangium both in vivo and in vitro. Several populations of mesangial cells were studied to determine if SMA and basement membrane collagen were regulated together. The levels of SMA expression, which could be linked to the stage of differentiation, were different for the differing cell populations. One cell population had high SMA and type IV collagen levels at its early passages. The others expressed both interstitial and basement membrane collagens. The first population developed these phenotypic features at later passages. The levels of SMA and alpha 1(IV) collagen expression were regulated together in concert, whereas the alpha 2(I) collagen levels were expressed inversely to SMA and alpha 1(IV) collagen. Both SMA and type IV collagen were controlled by the methylation states of the cis-regulators; however, type I collagen was mainly regulated by the trans-acting regulators. Treatment with 5-azacytidine converted the cells of a fibroblast-phenotype to a smooth muscle cell-like phenotype. These cell lines may be useful for studying the differentiation process in vitro.

Actins↗

PubMed1996

Characterization of the chicken follicle-stimulating hormone receptor (cFSH-R) complementary deoxyribonucleic acid, and expression of cFSH-R messenger ribonucleic acid in the ovary.

Studies were conducted to characterize the chicken (c) FSH receptor (R) cDNA, and to evaluate expression of cFSH-R mRNA in the hen ovary at known stages during follicle development. A total of 2.5 kb of nucleic acid sequence including the complete cFSH-R coding region was isolated by a combination of the reverse-transcription polymerase chain reaction and 5'- and 3'-rapid amplification of cDNA ends techniques. Overall, the nucleic acid sequence homology of the cFSH-R cDNA coding region is 71.8% and 72.2% compared to the rat and bovine FSH-R, respectively, while the deduced amino acid sequence identity for the receptor protein (693 amino acids) is 71.9% and 72.4%, respectively. By comparison, the cFSH-R nucleic acid and amino acid sequences are 60.1% and 49.4% identical to the respective cLH-R sequences. Northern blot analysis detected a single 4.3-kb cFSH-R mRNA transcript, which was selectively expressed in ovarian (granulosa, theca, and stromal) tissues, but not the oviduct, adrenal, liver, muscle, or brain. As the follicle developed from the prehierarchical (6- to 8-mm diameter) to the largest preovulatory (F1 follicle) stage, cFSH-R mRNA levels progressively declined within both the granulosa and theca layers (p < 0.05). Moreover, cFSH-R mRNA levels were lower in whole atretic than in morphologically normal 3- to 5-mm follicles (p = 0.0015). The pattern of cFSH-R mRNA expression within the granulosa layer during follicle development was notably different from that of the recently reported cLH-R, in that cLH-R mRNA levels increase to become readily detectable coincident with dramatically increased steroidogenic capacity during the last few days before ovulation of the follicle. On the other hand, highest levels of cFSH-R mRNA in 6- to 8-mm (prehierarchical) follicles were consistent with a role for the cFSH-R in maintaining the viability of prehierarchical follicles and in initiating granulosa cell differentiation at the time when follicles are selected into the preovulatory hierarchy.

Amino Acid Sequence↗

PubMed1996

Vasoactive intestinal peptide stimulates prolactin mRNA expression in turkey pituitary cells: effects of dopaminergic drugs.

It is well documented that vasoactive intestinal peptide (VIP) is a prolactin (PRL)-releasing factor and that dopamine (DA) is an inhibitory neurotransmitter in avian species. However, the roles of VIP and DA in the regulation of PRL gene expression are unclear. In this study, primary anterior pituitary cells cultured from laying turkeys were utilized to investigate the influence of VIP and dopaminergic D1 and D2 receptors on PRL secretion, PRL mRNA, and PRL synthesis. Incubation of pituitary cells with VIP increased PRL secretion up to 3.5-fold within 3 hr. Prolactin mRNA was undetectable during the first 2 hr of pituitary cell treatment; thereafter, the PRL mRNA content response to VIP increased with 24-48 h (P < 0.05). Total PRL content (media + cellular) increased over time in the presence of VIP. The response of cells incubated in the presence of a dopaminergic D1 receptor agonist (SKF38393) was variable and inconclusive. However, cells incubated with a dopaminergic D2 receptor agonist (quinpirole) inhibited VIP-induced PRL secretion (P < 0.05) and PRL mRNA levels (P < 0.05) in a dose-related fashion without effect on the basal levels of PRL release and PRL mRNA. These observations suggest that VIP, in addition to acting as a PRL-releasing peptide, also plays a role in the regulation of PRL gene expression. Moreover, the results of this study also indicate that a drug that can selectively stimulate dopamine D2 receptors can also regulate PRL secretion and PRL mRNA in turkey pituitary cells in culture.

Animals↗

PubMed1995

Modulation of ovarian cytochrome P450 17 alpha-hydroxylase and cytochrome aromatase messenger ribonucleic acid by prolactin in the domestic turkey.

The effect of exogenous ovine prolactin (oPRL) on preovulatory follicle P450 17 alpha-hydroxylase (C17) and aromatase (ARO) mRNA abundance was investigated in turkeys. Ovine PRL (124 IU/hen per day) was injected i.m. into four sets (n = 8) of laying turkeys for 2, 4, 8, or 14 days. Vehicle was injected into control hens for 8 days (n = 8). Blood samples were collected and serum was assayed for LH, progesterone (P), testosterone (T), and estradiol (E). Theca layers from the largest (F1) and the third (F3), fifth (F5), and seventh (F7) largest preovulatory follicles and from small white follicles (SWF) were examined for C17 and ARO mRNA contents. The number of atretic follicles increased from 0 (vehicle-injected controls) to 9 (14-day-oPRL-injected hens). Serum E, T, and LH levels decreased, while P levels remained unchanged. There was a transient increase in theca C17 mRNA abundance of 2- and 4-day-oPRL-treated hen follicles. Cytochrome P450 ARO mRNA levels were reduced in SWF and F7 in response to oPRL. Thecal C17 and ARO mRNA content was reduced during follicular maturation in laying hens. ARO mRNA was not detectable in granulosa cells. The progressive decline in C17 and ARO mRNA content associated with follicular maturation as well as the absence of ARO mRNA in granulosa cells is consistent with the secretory activity of P, T, and E in preovulatory follicles. These findings suggest that reduced circulating E may be a consequence of suppressed ARO gene expression whereas the oPRL suppression of T secretion may not be coupled to C17 gene expression.

Animals↗