bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of immediate early gene mRNAs and proteins by hCG in interstitial cells of rat testis
Authors: Schultz R , Kononen J , Pelto-Huikko M 
Published: December 2008

Abstract
In the present study we have investigated the induction of immediate early gene (IEG) c-fos, c-jun, junB and junD mRNAs and proteins in interstitial cells of rat testis after hCG treatment in vivo using in situ hybridization and immunocytochemistry. The basal levels of all IEGs were barely detectable with our methods. A prominent induction of c-fos, c-jun and junB mRNAs and proteins in Leydig cells was seen after hCG treatment. The induction of these IEG mRNAs and proteins demonstrates that their expression is an early transcriptional response to the extracellular stimulus of hCG and that they are involved in transcriptional processes which may mediate the effects of LH on cellular adaptive responses or steroid biosynthesis.
Journal of Endocrinology (1995) 144, 417–424
Dietary ω6 fatty acids and the effects of hyperthyroidism in mice
Authors: Deshpande N , Hulbert A J 
Published: December 2008

Abstract
The influence of the type of dietary fat on the effects of thyroid hormones was investigated in mice. Hyperthyroidism was achieved by providing thyroid hormones (T3 and T4) in the drinking water. Both hyperthyroid and euthyroid mice (Mus musculus) were fed isoenergetic diets containing 18% (w/w) total lipid but differing in fatty acid composition. Diets were either low in the polyunsaturated linoleic acid (18:2, ω6) and high in saturated fatty acids (SFAs) or low in saturated fats and high in the polyunsaturated fatty acid (PUFA), linoleic acid. Treatments were maintained for 21–22 days. Plasma thyroid hormone levels, standard metabolic rate (SMR), changes in body mass, specific activities of malic enzyme (ME), Na-K-ATPase and glycerolphosphate dehydrogenase (GPDH) of the liver were measured. Fatty acid composition of the liver phospholipids was also determined. Levels of T3 (15–17 nm) and T4 (250–255 nm) were significantly higher in the respective hyperthyroid groups. There was no significant influence of the diet on hormone levels. Hyperthyroidism increased the SMR 37–44% above the euthyroid levels. A significant body weight loss of 14–18% was observed in hyperthyroid mice on the PUFA diet but not in those on the SFA diet. PUFA diet significantly reduced the activity of ME but had no effect on Na-K-ATPase or GPDH activity. Activities of Na-K-ATPase and GPDH were significantly elevated in all hyperthyroid groups. Mice on T4 and PUFA diet showed a highly significant 399% increase in GPDH activity above the euthyroid level. The overall degree of unsaturation of the fatty acids in the liver phospholipids was comparable in all groups. Dietary treatment substantially changed liver membrane fatty acid composition whilst hyperthyroidism resulted in only small changes. The only parameters to show an interaction between dietary fat profile and hyperthyroidism were ME activity, changes in body mass and liver phospholipid fatty acid composition.
Journal of Endocrinology (1995) 144, 431–439
Effects of hemitransection of the midbrain on milk-ejection burst of oxytocin neurones in lactating rat
Authors: Wang Y-F , Negoro H , Honda K 
Published: December 2008

Abstract
Unilateral knife cuts were performed in the midbrain of lactating rats and the activities of oxytocin neurones were recorded extracellularly from the supraoptic nuclei (SON) in order to investigate the location of the neural mechanism responsible for the synchronization of milk-ejection bursts of oxytocin neurones in different magnocellular nuclei of the hypothalamus. The lesions involved the mesencephalic lateral tegmentum, the intermedial tegmentum and the central grey. Ninety-six SON neurones were antidromically activated by neurohypophyseal stimulation and were also identified as oxytocin neurones, which included 17 pair-recorded neurones. First, the response of oxytocin neurones recorded from the unilateral SON to bilateral or unilateral suckling was tested. During bilateral suckling, not only the oxytocin neurones recorded from the SON on the intact side (n=34) but also those recorded from the SON on the lesioned side (n=58) displayed milk-ejection bursts. When only the nipples ipsilateral to the lesion were suckled (ipsilateral suckling), bursts were induced in most of the oxytocin neurones on the intact (83·3%, n=12) and lesioned side (88·9%, n=27). In contrast, none of the oxytocin neurones (n=37) produced bursts and none of the rats tested (n=23) showed milk ejections during contralateral suckling. Secondly, some characteristics of the bursts of pair-recorded neurones during bilateral suckling and their response to different modes of suckling were investigated. When oxytocin neurones on both sides displayed milk-ejection bursts, they were always well synchronized but the mean burst amplitude of the neurones on the lesioned side (55·6 ±4·9 spikes, n=43) was significantly (P<0·05) lower than that of the neurones on the intact side (65·7 ±5·6 spikes, n=43). Late-recruited neurones were observed in 6 pairs of oxytocin neurones, and these mainly occurred in the neurones on the lesioned side (5/6). In 5 pair-recorded oxytocin neurones, bursts could also be induced synchronously by ipsilateral suckling but not by contralateral suckling. Thus it is very likely that the major mechanism synchronizing the milk-ejection bursts of oxytocin neurones in the bilateral SON is located in the region rostral to the midbrain.
Journal of Endocrinology (1995) 144, 463–470
Effects of catecholamine synthesis inhibitors and adrenergic receptor antagonists on restraint-induced LH release
Authors: Martín A I , Fernández-Ruiz J , López-Calderón A 
Published: December 2008

Abstract
Acute stress is known to increase LH secretion and the release of central norepinephrine (NE) in intact rats. Studies were performed to analyse the role of catecholamines in acute stress-induced LH release in male rats. Injection of α-methyl-p-tyrosine (αMPT) and diethyldithiocarbamate (DDC), catecholamine synthesis inhibitors, significantly decreased both hypothalamic concentration of NE and serum LH. Restraint for 30 min evoked an increase in serum LH in saline-treated rats, whereas αMPT and DDC administration blocked the stress-induced LH release. The effects of α1-, α2- and β-adrenoreceptor antagonists on the LH response to restraint stress were also studied. Propranolol treatment did not modify serum LH in either unstressed or stressed rats. The two α-adrenergic receptor antagonists prazosin and yohimbine prevented the restraint-induced LH release; however, prazosin but not yohimbine significantly decreased the serum concentration of LH in unstressed rats. These data suggest that the acute stress-induced increase in LH secretion is mediated through the activation of α2-adrenergic receptors.
Journal of Endocrinology (1995) 144, 511–515
Expression of mRNA and immunocytochemical localization of inhibin α- and inhibin βA-subunits in the fetal sheep testis
Authors: Thomas G B , Davidson E J , Engelhardt H , Baird D T , McNeilly A S , Brooks A N 
Published: December 2008

Abstract
In order to investigate the ontogeny of gonadal inhibin production in the male fetal sheep, testes were collected from male fetuses at days 70, 100, 130 and 140 of gestation (term=145 days). The expression and localization of inhibin α- and inhibin βA-subunit mRNA and protein were evaluated using in situ hybridization and immunocytochemistry. The expression of inhibin α-subunit mRNA was localized within the seminiferous cords of the developing fetal testis and progressively increased with gestational age. Immunostaining corresponding to immunoreactive inhibin α-subunit was detected in Sertoli cells within the seminiferous cords at days 100, 130 and 140 of gestation. In addition, immunostaining was detectable in a small proportion of Leydig cells. No expression of inhibin βA-subunit mRNA or immunoreactivity was detected in any testicular tissue at any stage of gestation. These data show that the Sertoli cells of the developing fetal sheep testis have the capacity to produce inhibin α-subunit by day 100 of gestation and that production increases during late gestation.
Journal of Endocrinology (1995) 145, 35–42
Effect of systemic glucagon administration on ACTH secretion in anaesthetized rats
Authors: Rao R H 
Published: December 2008

Abstract
The effect of glucagon on ACTH secretion was studied in anaesthetized rats injected with either saline (0·1 ml i.m.) or glucagon (0·02 mg/kg i.m.). For the first 90 min after glucagon injection, plasma ACTH fell by 50% from the basal value of 23 ±4 pmol/l (mean ± s.e.m.) to 11 ±2 (P=0·011), after which an abrupt return to baseline occurred (120 min value: 26 ± 2 pmol/l). In saline injected rats, the baseline ACTH value was not significantly different from either the 90 min value or the 120 min value (27 ±3 vs 21 ± 4 and 24 ± 3 pmol/l respectively; P>0·10). Plasma glucose after glucagon peaked at 11·6 ± 1·1 mmol/l by 15 min but subsequently fell rapidly, attaining the baseline by 60 min. Insulin levels increased sharply after glucagon, from 381 ±78 pmol/l to 3172 ±668 pmol/l at 15 min, and plateaued at approximately 1000 pmol/l thereafter. No changes in glucose or insulin were seen in saline injected rats. The magnitude of suppression of ACTH after glucagon was not affected either by sustained hyperinsulinaemia (≃ 1400 pmol/l), induced with continuous glucose infusion to maintain plasma glucose>12 mmol/l, or by pretreatment with the long-acting somatostatin analogue octreotide (50 μg/kg s.c.). However, the return to baseline between 100 and 120 min was prevented both by hyperinsulinaemia induced with sustained hyperglycaemia, and by octreotide. It is postulated that glucagon may inhibit ACTH secretion either by a direct effect on the hypothalamus or indirectly through insulin, which is known to stimulate endogenous somatostatin release.
Journal of Endocrinology (1995) 145, 51–58
Effect of gonadectomy on growth and GH responsiveness in dwarf rats
Authors: Gevers E F , Wit J M , Robinson I C A F 
Published: December 2008

Abstract
Normal rats are sexually dimorphic in their growth and GH secretion. Gonadectomy (Gnx) changes the GH secretory pattern and this could explain differential growth rates in male and female rats. Gonadal steroids may also affect tissue growth directly, or by changing their responsiveness to GH. The effects of Gnx on growth, GH responsiveness, and hepatic GH receptors have now been studied in young (4–7 weeks old) GH-deficient dwarf rats in which the effects of steroid-induced alterations in residual endogenous GH secretion will be much less pronounced. Groups of intact and Gnx dwarf rats (n=5–7) were infused with recombinant human GH (144 μg/day) either continuously or in a pulsatile pattern (every 3 h) for 7 days, whilst control groups received saline infusions. Gains in weight, length and tibial bone growth were measured. Female dwarf rats grew significantly more slowly than male dwarfs. Gnx in male dwarfs inhibited growth significantly, whereas ovariectomy had a lesser stimulatory effect in females. Hepatic lactogenic and somatogenic receptors were higher in females and ovariectomy lowered their values towards male levels. Pulsatile GH infusions were more effective than continuous infusions of the same daily GH dose, but when the different underlying growth rates (measured in saline-infused Gnx animals) were taken into account, the responsiveness to pulses of hGH was not different between males and females or between intact and Gnx animals. We have concluded that Gnx in dwarf rats does affect growth, but the effects are small in comparison with those seen in normal rats. Since pulsatile GH infusions stimulated growth more effectively than continuous GH, irrespective of the gonadal steroid status, and the responsiveness to exogenous GH was not changed by Gnx, the results imply that changes in the GH secretory pattern induced by gonadal steroids may have a larger impact on the growth rate than direct effects at the tissue level, at least in the rat.
Journal of Endocrinology (1995) 145, 69–79
Effects of thyroid hormone on coenzyme Q and other free radical scavengers in rat heart muscle
Authors: Mano T , Sinohara R , Sawai Y , Oda N , Nishida Y , Mokuno T , Kotake M , Hamada M , Masunaga R , Nakai A , Nagasaka A 
Published: December 2008

Abstract
Active oxygen species are reported to cause organ damage. This study was therefore designed to determine the behaviour of antioxidants and free radical scavengers so as to reveal changes in animals in the hyper- and hypothyroid state.
Levels of antioxidant factors (i.e. coenzyme Q (CoQ)10, CoQ9 and vitamin E) and free radical scavengers (catalase, glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD)) were measured in the heart muscles of rats rendered hyper- or hypothyroid by 4 weeks of thyroxine (T4) or methimazol treatment. Serum levels of CoQ9 and total SOD were also measured.
A significant reduction in CoQ9 levels was observed in the heart muscles of both hyper- and hypothyroid rats when compared with control hearts. There was no difference in serum CoQ9 levels in thyroid dysfunction when compared with control animals. Levels of vitamin E in the heart muscles of hyperthyroid rats were significantly increased, and there was no reduction in vitamin E levels in hypothyroid rats when compared with control hearts. GSH-PX levels in the heart muscle were reduced in hyperthyroid rats and increased in hypothyroid rats when compared with control hearts. However, there were no differences in catalase levels in heart muscle between hyper- and hypothyroid rats. The concentration of SOD in heart muscle was increased in hyperthyroid rats and was not decreased in hypothyroid rats compared with control rats, suggesting the induction of SOD by excessive production of O2−.
These data suggest that the changes in these scavengers have some role in cardiac dysfunction in the hyper- and hypothyroid state in the rat.
Journal of Endocrinology (1995) 145, 131–136
Peptide amidating activity and gastrin processing in the developing sheep pancreas
Authors: Kapuscinski M , Shulkes A 
Published: December 2008

Abstract
Gastrin is a regulator of both gastric acidity and gastrointestinal growth and is expressed transiendy in the neonatal ovine and human pancreas. C-terminal amidation of glycine extended gastrin (G-gly) to gastrin amide (G-amide) by peptidylglycine α-amidating mono-oxygenase (PAM) is the final processing step. To investigate the relationship between PAM and gastrin synthesis in the developing pancreas, we measured PAM activity and the concentrations of gastrins in ovine pancreatic extracts from 95 days of gestation onwards.
Pancreatic PAM activity was highest in the 95-day-old fetus (138 ±29 pmol/h/mg protein, mean ± s.e.m.) and decreased to 9·5 ±3·7 pmol/h/mg protein in the adult. The circulating enzyme was also highest in the youngest fetus (1840 ± 165 pmol/h/ml plasma) decreasing to approximately 50% in the 135-day-old fetus, with no further significant changes. The concentration of bioactive G-amide in the pancreas was 2·0 ±0·6 pmol/g at 95 days of gestation, 3·4 ± 0·9 pmol/g at 135 days and decreased to 0·7±0·1 pmol/g in the adult. The precursor G-gly followed a similar pattern but its concentration was less than 10% of G-amide. These results show that: (a) there are high levels of PAM activity in the ovine fetal pancreas and in the fetal circulation, (b) PAM activity is apparently not rate-limiting in the bioactivation of pancreatic gastrin and (c) the dual expression of both PAM and gastrin in the fetal pancreas is similar to that observed in peptide-secreting tumours of the adult.
Journal of Endocrinology (1995) 145, 137–142
Pancreatic changes in somatostatin content and receptor/effector system after intrapancreatic injection of 5,7-dihydroxytryptamine
Authors: Muñoz-Acedo G , Alvaro-Alonso I , Arilla E 
Published: December 2008

Abstract
To date, it is unknown whether intrapancreatic serotonergic nerves can influence pancreatic somatostatin (SS) content and the SS receptor/effector system in the exocrine pancreas. In this study, the intrapancreatic serotonergic nerves were chemically ablated by injecting a specific serotonin (5-HT) neurotoxin, 5,7-dihydroxytryptamine (5,7-DHT), into the substance of the gland. Three days after the injection, the 5-HT-like immunoreactive levels in the pancreas were reduced by more than 85% whereas somatostatin-like immunoreactive levels had increased (86%). The number of SS receptors in the pancreatic acinar cell membranes of the 5,7-DHT-treated rats was also increased (72%). No significant differences were seen in basal or forskolin-stimulated adenylate cyclase (AC) enzyme activities in the control and the 5,7-DHT-treated groups. In spite of the increase in the number of SS receptors in the pancreatic acinar cell membranes of 5,7-DHT-treated rats, SS caused a significantly lower inhibition of AC activity in these membranes. This finding is related to the observed decrease of a 41 kD pertussis toxin-sensitive substrate, presumably the αi subunit of the guanine nucleotide inhibitory protein, in pancreatic acinar cell membranes 3 days after intrapancreatic 5,7-DHT administration when compared with the corresponding controls. The functions of pancreatic serotonergic nerves seem to be associated with enteropancreatic communication. These data together with the present results suggest that pancreatic SS content and the SS receptor/effector system in the exocrine pancreas may be regulated by enteropancreatic serotonergic nerve fibers and may participate in enteropancreatic reflexes.
Journal of Endocrinology (1995) 145, 227–234
Neuropeptide Y modulates the sensitivity of the rat adrenal cortex to stimulation by ACTH
Authors: Hinson J P , Cameron L A , Kapas S 
Published: December 2008

Abstract
Neuropeptide Y (NPY) has been identified in nerves supplying the adrenal cortex of several mammalian species, although its function in this tissue is unknown. The present studies, employing adrenocortical cells prepared by collagenase digestion, have shown that NPY, in the absence of other stimulants, has no effect on steroid secretion by the rat adrenal over a range of peptide concentrations (10−11 to 10 −6 mol/l). However, in the presence of physiological concentrations of ACTH, which are submaximal for the stimulation of aldosterone secretion, NPY (10−6 mol/l) significantly enhanced the secretion rate of aldosterone by rat zona glomerulosa cells in response to ACTH. This effect was specific to the rat zona glomerulosa as NPY had no effect on the response to ACTH in rat zona fasciculata cells. The effect of NPY appears to be biphasic, however, as NPY significantly attenuated the steroidogenic response to supramaximal ACTH concentrations: in rat zona glomerulosa cells the aldosterone response to 10 −8 mol ACTH/l was significantly inhibited by NPY. The effect of NPY on the ACTH response appeared to be mediated by changes in the cAMP response. NPY had no effect on the steroidogenic response to potassium ions (K+), but enhanced the response to angiotensin II. NPY (10 −6 mol/l) significantly stimulated inositol 1,4,5-trisphosphate (InsP3) production although this concentration of peptide had no effect on steroid secretion. The effects of NPY on InsP3 production were additive with those of angiotensin II. These results suggest that the role of NPY in the adrenal cortex may be to regulate the sensitivity of the zona glomerulosa to peptide stimulation.
Journal of Endocrinology (1995) 145, 283–289
Absence of the oxytocin-induced prostaglandin F2α secretory response in uterus from ovariectomized ewes and activation of the response in vitro
Authors: Sheldrick E L , Flick-Smith H C , Bendall D E , Flint A P F 
Published: December 2008

Abstract
Oxytocin-induced prostaglandin F2α (PGF2α) responses were measured in explants of uterus from ovariectomized ewes on the day of tissue collection or after culture for 72 h in the presence or absence of oestradiol-17β (100 nmol/l). Oxytocin receptor binding activity was 210 ±47 fmol [3H]oxytocin bound per mg protein in fresh tissue and 89 ± 24 and 90 ± 17 fmol/mg in tissue cultured with control medium or with oestradiol respectively (means ± s.e.m.).
PGF2α production during the hour following oxytocin administration to freshly collected tissue was 272 ± 77 ng/g/h compared with 193 ± 35 ng/g/h in the absence of oxytocin. These rates were 2789 ± 1085 and 353 ± 135 ng/g/h after culture for 72 h in control medium and 2022 ± 496 and 342 ± 134 ng/g/h after culture with oestradiol. Thus oestradiol had no effect on the culture-induced maturation of the PGF2α response. Short-term exposure to arachidonic acid (66 μmol/l) did not increase PGF2α production in fresh tissue but significantly increased basal but not oxytocin-induced PGF2α production after 72 h in culture (P<0·05). There was an absence of oxytocin-induced inositol phosphate turnover in fresh tissue but after culture concentrations of inositol mono-, bis- and trisphosphates were all significandy increased by oxytocin (P<0·005). Antisera directed against G-protein α sub-units αi3, αo, αq, α11 and the common β subunit, and prostaglandin H-synthase-1 detected proteins that were present before and after culture. Oestradiol had no effect on the presence or apparent concentrations of these proteins.
Journal of Endocrinology (1995) 145, 299–305
A mixture of the branched chain amino acids leucine, isoleucine and valine increases ovulation rate in ewes when infused during the late luteal phase of the oestrous cycle: an effect that may be mediated by insulin
Authors: Downing J A , Joss J , Scaramuzzi R J 
Published: December 2008

Abstract
The positive relationship between nutritional state and ovulation rate in sheep may involve the action of specific nutrients on gonadotrophin release. LH and FSH secretion is controlled in part by hypothalamic GnRH, which is in turn influenced by central adrenergic and serotonergic neuronal systems. In this experiment the branched chain amino acids (BCAAs) leucine, isoleucine and valine were examined for effects on LH and FSH secretion. A mixture of the three amino acids was infused into ewes for 5 days immediately before luteolysis, a time when nutritional effects on ovulation rate occur.
The infusion significantly increased ovulation rate without any associated increase in FSH or LH. However, the infusion did increase plasma insulin concentrations and this effect, together with the high levels of blood urea observed, suggests that these amino acids had increased the supply of energy substrates to the follicles. An increase in insulin-mediated glucose uptake by follicles could be the stimulus responsible for the increase in ovulation rate. The ability of the animal to utilize BCAAs for energy metabolism may be an important component of the ovulation responses to nutrition.
Journal of Endocrinology (1995) 145, 315–323