Biomedical subjects

N C Stickland

Publications and source records attributed to N C Stickland.

At least 19 recordsLinked to original sources

PubMed2006

Neuromuscular stimulation causes muscle phenotype-dependent changes in the expression of the IGFs and their binding proteins in developing slow and fast muscle of chick embryos.

Insulin-like growth factor (IGF) -1 and -2 and binding protein (IGFBP-2, -4, and -5) expression can be affected by several environmental factors, but the impact of movement on the IGF axis during late embryogenesis has yet to be fully characterized. Movement was promoted in chick embryos during mid-embryogenesis using 4-aminopyridine (4-AP). The results indicate an increase in IGF-1 (P < 0.01) and a decrease in IGFBP-2 (P < 0.05) mRNA expression in slow muscle of the stimulated group compared with the control group. In fast muscle, there was a decrease in IGF-2 (P < 0.01) on embryonic day (ED) 16 and an increase in IGFBP-2 (P < 0.01) and IGFBP-4 (P < 0.05) and in IGFBP-5 (P < 0.05) expression on ED18 in the stimulated group compared with the control group. These results indicate that neuromuscular stimulation with 4-AP influences IGF axis gene expression in a muscle fiber type-dependent manner. Consequences of the changes in the IGF system for each muscle are discussed.

4-Aminopyridine↗

PubMed2005

In ovo neuromuscular stimulation alters the skeletal muscle phenotype of the chick.

4-aminopyridine (4-AP) is a drug that blocks the potassium channels in neurons and stimulates the release of the neurotransmitter acetylcholine (ACh), enhancing its availability at the synaptic cleft. The effects of 4-AP induced neuromuscular stimulation on skeletal muscle formation and development were investigated in embryonic chicks. Fertile white Leghorn eggs were incubated at 37.5 degrees C and windowed on day three of incubation. On embryonic days (E) 10, 11, 12 and 13 half of the eggs were injected with 100 microl of PBS buffer containing 0.2 microg 4-AP and the control group was administered 100 microl of PBS only. 4-AP treated (T) embryos showed at least a 10% increase in mean body mass relative to the controls (C) (P<0.05) at ages E14, E15 and E16. Tibia and femur lengths in the 4-AP treated embryos were significantly greater than the controls at E15 and E16 (P<0.05). The 4-AP treated animals had a 36.8% greater number of myofibres than the control animals at E20. Nuclear number per cross sectional area in the M. Semitendinosus was significantly greater (P<0.01) at E16 in the treated compared to the control embryos. The 4-AP treated group exhibited a greater percentage area of oxidative fibres in cross sections of M. Semitendinosus than the control group at E16 (P<0.01) and at E20 (P<0.05). It may be concluded from these results that 4-AP induced neuromuscular stimulation has a significant effect on skeletal muscle characteristics, leg bone length and overall body mass.

4-Aminopyridine↗

PubMed2005

Fetal programming of fat and collagen in porcine skeletal muscles.

Connective tissue plays a key role in the scaffolding and development of skeletal muscle. Pilot studies carried out in our laboratory have shown that the smallest porcine littermate has a higher content of connective tissue within skeletal muscle compared with its largest littermate. The present study investigated the prenatal development of intralitter variation in terms of collagen content within connective tissue and intramuscular fat of the M. semitendinosus. Twenty-three pairs of porcine fetuses from a Large White-Landrace origin were used aged from 36 to 86 days of gestation. The largest and smallest littermates were chosen by weight and the M. semitendinosus was removed from each. Complete transverse muscle sections were stained with Oil Red O (detection of lipids) and immunocytochemistry was performed using an antibody to collagen I. Slides were analysed and paired t-Tests revealed the smallest littermate contained a significantly higher proportion of fat deposits and collagen I content compared with the largest littermate. Recent postnatal studies showing elevated levels of intramuscular lipids and low scores for meat tenderness in the smallest littermate corroborate our investigations. It can be concluded that the differences seen in connective tissue elements have a fetal origin that may continue postnatally.

Adipose Tissue↗

PubMed2004

In ovo temperature manipulation influences post-hatch muscle growth in the turkey.

1. The effect of manipulating egg incubation temperature for short periods on turkey muscle development was determined using the M. semitendinosus, a thigh muscle, as the model. 2. Experiment 1. Eggs were incubated at a control temperature of 37.5 degrees C. For a 4-d period of 0 to 4, 5 to 8, 9 to 12, 13 to 16, 17 to 20 or 21 to 24 embryonic days (ED) eggs were transferred to either 38.5 or 35.5 degrees C. A regime of 38.5 degrees C at 5 to 8 and 9 to 12 ED caused an increased myonuclei number and muscle fibre number, respectively. 3. Experiment 2. Eggs were incubated at a control temperature of 37.5 degrees C. At 5 to 8 ED eggs were transferred to 38.5 or 35.5 degrees C. Temperature-manipulated embryos showed a delay in differentiation (myogenin expression) of the semitendinosus muscle compared to controls. 4. Manipulating the incubation temperature for 4 d in early incubation alters muscle development in the turkey with no observation of deformities or reduction in hatchability. We speculate that this increase in temperature may result in an improved muscle growth in the post-hatch bird.

Animal Husbandry↗

PubMed2001

Maternal treatment with somatotropin during early gestation affects basic events of myogenesis in pigs.

The effects of maternal treatment with somatotropin during early gestation on fetal muscle development were determined. Crossbred gilts received daily injections of either 3 ml of a placebo ( n=31) or of 6 mg porcine somatotropin ( n=31) from day (d) 10 to 27 of gestation and samples were collected from d 28 embryos, d 37 and 62 fetuses, and from neonates. Administration of somatotropin increased the total number of fibres (primary and secondary fibres) in neonatal semitendinosus muscle of middle- and low-weight littermates, whilst no increase was observed in psoas major muscle. Somatotropin induced increases in muscular protein concentration, creatine kinase activity, muscle fibre girth, as well as type II to type I fibre conversion which revealed an advanced degree of differentiation at birth. Treatment effects on prenatal development preceded these changes. Increased DNA concentrations at d 28 of gestation indicate stimulation of cellular proliferation during the embryonic stages. Thereafter, the withdrawal of somatotropin caused a transient delay of differentiation as indicated by lower protein concentrations and creatine kinase activity compared with controls at d 37 of gestation. This was compensated again at d 62, and the number of semitendinosus primary fibres was increased in middle-weight fetuses, whereas secondary or total fibre number did not yet differ. However, enhanced expression of Myf5 and MyoD indicates higher numbers of initially determined, proliferating myoblasts that may have contributed to increased formation of secondary fibres. In conclusion, maternal somatotropin is an influential factor in early pregnancy capable of affecting the basic events of myogenesis.

Animals↗

PubMed2001

Changes in tissue cellularity are associated with growth enhancement in genetically modified arctic char (Salvelinus alpinus L.) carrying recombinant growth hormone gene.

Biochemical and histological analyses were used to study the number and size of cells (cellularity) in tissues of fast-growing, genetically modified Arctic char (Salvelinus alpinus L.), overexpressing sockeye salmon (Oncorhynchus nerka) growth hormone gene (OnGH1). DNA contents of muscle, heart, and liver were compared in transformed, sibling (age control) and 1 year older (size control) char. Total white muscle cross-sectional area, white muscle fiber number, and total nuclei number within the muscle tissue were determined from one complete half-section of each fish. The analyzed tissues responded differently to growth hormone overproduction. In muscle tissue of OnGH1-transformed char, the enhanced growth was clearly associated with proliferation of muscle cells (hyperplasia), whereas in heart tissue both cell proliferation and increase in cell size (hypertrophy) were enhanced. The relative DNA concentration in the liver of transformed char was significantly greater than that of control fish, suggesting reduction in size of hepatic cells.

Journal Article↗

PubMed2001

Lower environmental temperature delays and prolongs myogenic regulatory factor expression and muscle differentiation in rainbow trout (Onchrhynchus mykiss) embryos.

The effect of different temperatures (4 degrees C and 12 degrees C) on myogenic regulatory factors (MyoD and myogenin) and myosin heavy chain (MyHC) expression was investigated in rainbow trout (Onchrhynchus mykiss) during early development. MyoD is first switched on at stage 14 [about 5 somites are formed (1/2 epiboly)] while myogenin mRNA is expressed at stage 15 [around 15 somites are visible (2/3 epiboly)] at both temperatures. Subsequently (up to at least stage 20), the most caudal somites exhibit less myogenin mRNA at 4 degrees C compared to 12 degrees C. At the eyed stage (stage 23-24), both myogenin mRNA and protein are present in greater amounts throughout all myotomes at the lower temperature, with mRNA levels in warmer (12 degrees C) embryos at 83% for MyoD and 72% for myogenin of the levels seen in 4 degrees C embryos. Conversely, however, at this same stage, fast-MyHC mRNA and protein are more abundant in 12 degrees C than in 4 degrees C embryos. This indicates relatively advanced muscle differentiation at the warmer temperature. At hatching, myogenin-positive cells are concentrated within the myosepta at both temperatures and they are also sparsely distributed in the myotome at 4 degrees C, but not at 12 degrees C. MyoD, myogenin, and MyHC levels provide an indication of differentiation of muscle cells. These findings suggest that myogenic regulatory factor expression is delayed but prolonged by the lowering of temperature.

Animals↗

PubMed2001

Temperature and myogenic factor transcript levels during early development determines muscle growth potential in rainbow trout (Oncorhynchus mykiss) and sea bass (Dicentrarchus labrax).

The influence of changes in environmental temperature on the mRNA levels of myogenic regulatory factors (MRFs), i.e. MyoD and myogenin, as well as myosin heavy chain (MyHC) were studied during early larval development in rainbow trout and sea bass. Phosphoimager analysis of northern blots indicated that there is an optimum temperature for the RNA transcript levels of MRF and MyHC RNA in trout and in sea bass larvae. In the trout strain studied, the highest concentration for MRF and MyHC transcripts was found at 8 degrees C rather than 4 degrees C or 20 degrees C. In European sea bass, the highest concentrations of MRF and MyHC mRNA were observed at 15-20 degrees C rather than 13 degrees C. Raising sea bass larvae at 15 degrees C was associated with higher MyHC gene expression as well as a trend towards an increase in total muscle fibre number and higher growth rates after transfer at ambient temperature. Results suggest that mRNA levels of MRF and MyHC can be used to optimise early development. An experiment in which the temperature was changed illustrates the consequence of precise temporal expression of MRF genes in specifying muscle fibre number at critical stages during early development.

Animals↗

PubMed2000

The expression of the myogenic regulatory factors in denervated and normal muscles of different phenotypes.

The nerve is known to play a pivotal role in the diversification of muscle fibre types postnatally. Reducing neuronal activity in a slow muscle such as the soleus by denervation, switches on genes associated with a fast muscle phenotype. On the other hand, denervating a fast muscle such as the extensor digitorum longus (EDL) induces the conversion of fast fibres to a 'slower' contractile phenotype. The myogenic regulatory factors (MRFs) are proposed as the regulators of muscle phenotype as MyoD and myogenin have been shown to differentially accumulate in fast and slow muscle upon the induction of fibre type transformation. The denervation model has been used in the present study to induce changes in MRF expression in the muscles of the lower hindlimb which have distinct phenotypic characteristics. The level of MRF expression in pairs of denervated and innervated soleus, EDL, tibialis anterior (TA), plantaris and gastrocnemius muscles has been determined by Northern analysis and compared. The present study has shown that each muscle responds differently to denervation with respect to the increases in MRF expression. Fast muscles responded very quickly to denervation by increasing the level of MRF transcripts while slow muscles did not show significant increases in expression after 48 h denervation. The innervated EDL (fast) and soleus (slow) muscle differed with respect to the level of MRF-4 expressed, MRF-4 being expressed at higher levels in the slow muscle compared to the fast, suggesting that MRF-4 is important in the maintenance of a slow muscle phenotype. Moreover, MRF-4 and myogenin show the greatest fold increases in expression in the fast muscles examined. MyoD and Myf 5 show less dramatic increase in expression in response to denervation but exhibit the greatest fold increases in the fast muscles compared to slow.

Animals↗

PubMed2000

MRF-4 exhibits fiber type- and muscle-specific pattern of expression in postnatal rat muscle.

The crucial role played by the myogenic regulatory factors (MRFs) in the development of skeletal muscle has been well characterized. The continued expression of these factors in skeletal muscle of the postnatal animal has led to the suggestion that they may play a role in the regulation of muscle fiber phenotype. The few studies that have examined the expression of MRF-4 in postnatal muscle have been carried out at the whole muscle level. These studies demonstrated that this factor is expressed at a higher level than any other MRF but suggested that this was not affected by muscle phenotype. In this study, the expression of the MRF-4 transcript has been examined at the cellular level by in situ hybridization. It was observed that in the mixed fiber type muscle the gastrocnemius, MRF-4 was preferentially expressed in slow muscle fibers, but in the slow postural soleus, no fiber type specificity was observed. These observations suggest that MRF-4 may play a role in the regulation of muscle fiber phenotype in the postnatal animal.

Animals↗

PubMed1995

The growth of Atlantic salmon (Salmo salar L.) myosatellite cells in culture at two different temperatures.

Temperature is known to affect fish growth, and in Atlantic salmon there is an influence on muscle cellularity. Primary muscle cell culture makes it possible to investigate direct effects of temperature on myogenic cells. Salmon myosatellite cells were cultured for the first time in this study. The cells were cultured at either 5 degrees C or 11 degrees C. Increased temperature led to an increase in differentiation rate and especially hypertrophic growth (Q10 = 4.0). No nuclear proliferation was evident in the satellite cell population isolated at either temperature. This may be due to the presence of different subpopulations of myogenic cells at different developmental ages or the presence of indirect factors in vivo.

Animals↗

PubMed1995

Effect of maternal undernutrition in early gestation on the development of fetal myofibres in the guinea-pig.

A 40% restriction in maternal feed intake throughout gestation in the guinea-pig results in a 35% reduction in fetal body weight at term and a 20-25% reduction in muscle fibre number. To investigate the effect of maternal undernutrition in early gestation, four nutritional treatments were used: controls-pregnant females fed ad libitum throughout gestation; TR-fed 60% ad libitum intake throughout gestation; ER-fed 60% ad libitum for the first third of gestation (until Day 25), then ad libitum to term; LR-fed ad libitum for the first 25 days, then 60% of ad libitum to term. The LR group were complicated by a high degree of fetal resorption and early littering of viable litters. The biceps brachii and soleus muscles were removed from neonates and total muscle fibre numbers determined. In a second experiment a further 8 pregnant guinea-pigs were fed 60% ad libitum until Day 15 of gestation only, and then rehabilitated onto an ad libitum diet (VER). Of these, 5 guinea-pigs were killed at term and the remaining 3 at 45 days gestation. Fetuses and placentae were obtained from all VER animals and compared with TR and controls of a similar age. Body weights were reduced in all restricted groups at term when compared with controls (P < 0.05) by 12, 40 and 50% for VER = ER, TR and LR groups, respectively. Biceps fibre number was reduced (P < 0.05) in ER, TR and LR groups by 28, 20 and 25%, respectively, but was not affected in the VER group. Soleus fibre number was not significantly affected by any nutritional treatment. Restriction for 15 days in early gestation caused a significant 20% increase in fetal weight at 45 days' gestation compared with controls, but muscle and placental weights were not affected. Analysis of placental components at Days 45 and 65 suggested that underfeeding in early gestation and subsequent refeeding caused some placental adaptations to increase the exchange-surface area. A short period of maternal undernutrition in the first third of gestation alone (ER), therefore, resulted in a biceps brachii fibre number deficit similar to that caused by restriction throughout gestation only if the period of restriction extended as far as Day 25. Furthermore, fetal weight at term was impaired by short-term nutritional restriction in early gestation. Restriction in the last two-thirds of gestation, following an ad libitum diet in the first third, caused a reduction in biceps fibre number and had a severe effect on the maintenance of pregnancy. It is probable that undernutrition in early gestation had an indirect effect on muscle fibre number by affecting the development of the placenta. This could be avoided by nutritional rehabilitation before Day 25 of gestation, but appeared to be permanent thereafter. Undernutrition after Day 25 may have had a direct effect on the development of secondary fibres.

Animals↗

PubMed1994

The influence of male-specific genes on female muscle fiber types: studies on the sex-reversed (Sxr) mouse.

Previous experiments on the effects of either male castration or injection of androgens have concluded that levels of androgens are responsible for different muscle fiber type proportions between the sexes. However, these conclusions are based on invasive techniques which may involve secondary factors. The sex-reversed (Sxr) mouse is genetically female (X/X) but phenotypically male due to the presence of part of the short-arm of the Y chromosome containing the testis determining gene (Tdy). Serum testosterone in this mouse is in the low normal range and therefore provides a model for investigating the possible control of muscle fiber types by male specific genetic factors. Ten males, ten females, and ten Sxr mice of approximately 60 days of age were used, together with ten males weight-matched to the females. The animals were killed and biceps brachii and soleus muscles removed and prepared for routine muscle histochemistry. Body and muscle weights were similar in the males and Sxr mice and significantly greater than in the females and the weight-matched males. Muscle fiber sizes in biceps brachii reflected the differences in muscle weights and there were no significant differences in fiber type proportions for this muscle. In the soleus muscle, the percentage of slow, oxidative (SO) fibers was higher in the female mice than in any other group. Furthermore, although the fast, oxidative, glycolytic (FOG) fibers were larger in the heavier animals, SO fibers were largest in the female mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Supplementation of a restricted maternal diet with protein or carbohydrate alone prevents a reduction in fetal muscle fibre number in the guinea-pig.

A 60% reduction in maternal feed intake is known to cause a reduction of approximately 20% in biceps brachii fibre number in the guinea-pig fetus. This investigation was designed to isolate the dietary component responsible by reducing all dietary components to 60% of the ad lib. level and supplementing the protein, carbohydrate or fat component to the level of the ad lib. intake. Fetal muscles were examined at 50 d gestation to determine numbers of primary and secondary fibres, and at term to determine total fibre number. Fetal and neonatal weights were reduced in all restricted groups (P < 0.05) when compared with ad lib. controls. At term this reduction was significantly less (P < 0.05) in the protein-supplemented group (20%) than in the 60%-restricted and fat-supplemented groups (43%) and the carbohydrate-supplemented group (34%). Biceps brachii fibre numbers were reduced in the 60%-restricted fat-supplemented groups by 14-16%, but fibre numbers were similar in control, protein-supplemented and carbohydrate-supplemented groups. Any reduction in fibre number was in the secondary fibre component of total fibre number. Therefore, biceps brachii fibre numbers were reduced only when maternal diets were deficient in both protein and carbohydrate.

Animal Nutritional Physiological Phenomena↗

PubMed1994

Effects of pituitary dwarfism in the mouse on fast and slow skeletal muscles.

The Snell dwarf mouse exhibits impaired growth of the anterior pituitary resulting in reduced levels of growth hormone and thyroid stimulating hormone. Ten dwarf mice and 10 phenotypically normal littermates were killed at 33 days of age. M. biceps brachii (a predominantly fast muscle) and m. soleus (a relatively slow muscle) were removed from each animal and complete frozen transverse sections obtained. Serial sections were reacted for various enzyme activities in order to identify muscle fibre types. There was no difference in the total number of muscle fibres in m. biceps brachii but a small difference in m. soleus between normal and dwarf mice. There were marked differences in the size of all fibre types between normal and dwarf mice with the largest differences in m. soleus. The percentage of slow oxidative fibres was similar (about 32%) in both groups of mice for m. soleus but there was a marked difference for this fibre type in m. biceps brachii being about 1.5% in normal mice and 8.0% in dwarf mice. This may be related to a difference in levels of thyroid hormone. Nuclear density was very significantly greater in dwarf muscles although total nuclear numbers were less than in normal muscles. These differences are most likely due to growth hormone levels. Differences in nuclear content were much greater in m. soleus than in m. biceps brachii.

Animals↗

PubMed1994

The influence of maternal nutrition on muscle fiber number development in the porcine fetus and on subsequent postnatal growth.

In the pig, undernutrition in utero causes low birth weight, a decrease in muscle fiber number, and a reduction in postnatal growth rate. The effect on fiber number is mediated via a reduced secondary fiber population. Within a litter of pigs, lighter-weight pigs have probably suffered some deficit in muscle fiber number. In an attempt to improve the number of fibers in the lighter-weight pig fetuses, four maternal feeding regimens were used, one serving as the control. Maternal feed intake was doubled for one of three time periods during pregnancy: 1) d 25 to 50 (HE) immediately before fiber hyperplasia; 2) d 50 to 80 (HL) during fiber hyperplasia; or 3) d 25 to 80 (HT) covering both developmental events. Controls were fed at levels routinely used for pregnant sows on the farm. Sows farrowed normally and pig birth weights were recorded. Estimates were made of total myofiber number, total primary fiber number, and mean secondary:primary fiber number ratio (S:P) for the semitendinosus of each pig at 5 wk postnatal or 80 kg (HT and two control litters only). The progeny of all supplemented sows had a significantly greater mean S:P ratio (P < .05), and the HE pigs tended to have a greater number of muscle fibers than control pigs (403,840 +/- 8,197 vs 370,970 +/- 12,720). Postnatal growth rate to 80 kg was also investigated for the HT group of pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1994

Inability of muscles in the obese mouse (ob/ob) to respond to changes in body weight and activity.

The fat-free carcass weight of the obese mouse (ob/ob) is generally less than that of wild-type siblings. The aim of this investigation was to examine the effect of obesity on muscle weights and histochemistry and to determine whether any effects could be eliminated when the obesity was largely prevented or reduced by limiting food intake. For 5 muscles examined the weights were significantly greater (except for biceps brachii) in the wild-type than in obese mice. Although there was a significant correlation between muscle weight (except for soleus) and body weight in the wild-type mice, no such correlation held for the obese mice. No remarkable differences between groups of mice were found in the histochemistry of the biceps brachii and soleus muscles except that fibre sizes were generally smaller in the obese mice. It is concluded that the skeletal muscles of obese mice cannot respond to the increased activity associated with prevented or reduced obesity.

Animals↗

PubMed1994

Muscle at birth in mice selected for large and small body size.

Selection for divergent body weight at 6 wk of age in the Q strain mouse has produced large (QL) and small (QS) mice which differ 2-fold in their adult body weight. The purpose of this investigation was to identify some of the cellular mechanisms which underlie the early divergence in size between the 2 lines. At birth, QL mice (for similar litter sizes) were 28% heavier and 6% longer than QS mice. This was reflected by measurements of longitudinal bone length which were greater in QL (tibia 6.2%, humerus 4.2%) compared with QS mice. Fibre number was found to be 18 and 17% greater in the biceps brachii and soleus muscles respectively of the QL mice. It was concluded that this was not a consequence of any alteration in the ratio of developing secondary to primary myofibres in either muscle. Fibre cross-sectional areas were only significantly different between the QL and QS for the soleus muscle, which might be explained by the relatively greater divergence in the length of its supporting bone (tibia) between the QL and QS compared with the humerus. Estimates of nuclear number showed that there were significantly more nuclei in biceps brachii muscle of QL than in the QS mice which could be attributed to the difference in fibre number, although no such differences were found for the soleus muscle. There was no apparent alteration in the proportion of nuclei found within the fibres of the biceps muscle. Overall the results indicate that selection in this situation has acted through the normal cellular processes of growth.

Animals↗