bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of thyroid status on brain catecholamine biosynthesis in adult rats: assessment by a steady-state method
Authors: Harris P. E. , Dieguez C. , Lewis B. M. , Hall R. , Scanlon M. F. 
Published: December 2008

ABSTRACT
Effects of thyroid status on brain catecholamine turnover in adult rats were investigated using a steady-state method. Rats were treated for 3 weeks with s.c. injections of l-thyroxine (0·4 mg/kg), aminotriazole in drinking water (0·1%, w/v) or vehicle. After 2 weeks of treatment rats were implanted chronically with lateral intracerebroventricular (i.c.v.) cannulae. They were injected i.c.v. with [3H]tyrosine 1 week later. Catecholamine and tyrosine content and specific activity were measured in mediobasal hypothalamus, anterior hypothalamus and striatum, using high-performance liquid chromatography with electrochemical detection. Thyroxine treatment resulted in a significant increase in noradrenaline and dopamine synthesis localized to the mediobasal hypothalamus. Conversely, aminotriazole treatment resulted in a significant decrease in noradrenaline synthesis localized to the mediobasal hypothalamus. The localization of these changes in catecholamine turnover to the mediobasal hypothalamus suggests that they may be specific functional effects which are of importance in the overall integrated control of thyroid function.
J. Endocr. (1986) 111, 383–389
Effects of a single injection of a new depot formulation of an LH-releasing hormone agonist on spermatogenesis in adult rats
Authors: van Kroonenburgh M. J. P. G. , Beck J. L. , Vemer H. M. , Rolland R. , Thomas C. M. G. , Herman C. J. 
Published: December 2008

ABSTRACT
Adult male Wistar rats were treated with a single injection (500 μg s.c.) of a new biodegradable depot formulation of the LH-releasing hormone (LHRH) analogue [d-Ser(But)6]AzGly10-LH-RH (Zoladex; ICI 118 630) to evaluate its potential for inhibiting spermatogenesis. The drug produced a marked (P≤0·05) decrease in serum concentrations of FSH, LH and testosterone with a maximum effect 14 days after treatment. Since striking focal histological changes were seen in the testis after only 1 week, at a time when changes in serum gonadotrophins were minimal, there may be a direct effect of the LHRH analogue on spermatogenesis. Degenerative changes in germ cells as well as Sertoli cells could be observed. Flow-cytometric analysis of testicular cell suspensions showed a significant decline in the absolute numbers of haploid cells (spermatids), tetraploid cells (mainly pachytene spermatocytes) and of the numbers of cells in the S-phase of the cell cycle. This suggests that the drug also inhibits proliferation of spermatogonia and/or primary spermatocytes. Testis weight, serum hormone concentrations, and histological and cytological parameters returned to essentially normal values 52 days after the injection. It is concluded that this new method of administration may have practical and pharmacokinetic advantages for the purpose of reversible inhibition of spermatogenesis.
J. Endocr. (1986) 111, 449–454
Hypoglycaemia and acute stress-induced hyperinsulinaemia in mice infected with Bordetella pertussis or treated with pertussis toxin
Authors: Sidey F. M. , Wardlaw A. C. , Furman B. L. 
Published: December 2008

ABSTRACT
Intranasal infection of mice with a sublethal dose of Bordetella pertussis produced hypoglycaemia and hyperinsulinaemia. Exposure to ether vapour did not modify serum insulin concentrations in control mice, but produced a marked transient hyperinsulinaemia in mice infected with B. pertussis. A similar hyperinsulinaemia in infected, but not control, mice was also seen after a brief (10–15 s) period of anoxia (produced by exposure to an atmosphere of 100% N2 or 100% CO2), or following the injection of histamine or 2-deoxyglucose. Exposure to cold (2–4 °C) or hypoxia (8% O2 in 92% N2), however, did not alter serum concentrations of insulin in control or infected mice.
The hyperinsulinaemic response to ether stress observed in mice infected with B. pertussis was abolished by pretreatment with alloxan.
The hyperglycaemic effects of histamine and 2-deoxyglucose were attenuated or abolished in mice infected with B. pertussis. However, none of the stimuli which produced hyperinsulinaemia in the infected mice resulted in any further lowering of the blood glucose concentration.
Pretreatment of mice with pertussis toxin (150 ng/mouse, i.v.) produced hypoglycaemia similar in magnitude to that found in animals infected with B. pertussis. Moreover, exposure of mice treated with pertussis toxin to ether vapour produced marked hyperinsulinaemia.
It is suggested that the metabolic alterations seen in animals infected with B. pertussis may be mediated by pertussis toxin.
J. Endocr. (1987) 112, 113–122
Recombinant human insulin-like growth factor: testing the somatomedin hypothesis in hypophysectomized rats
Authors: Skottner A. , Clark R. G. , Robinson I. C. A. F. , Fryklund L. 
Published: December 2008

ABSTRACT
The in-vivo biological activity of recombinant methionyl insulin-like growth factor I (met-IGF-I) was demonstrated in hypophysectomized rats by following blood glucose after an i.v. bolus injection of met-IGF-I; a dose-dependent decrease in blood sugar was seen. Membrane transport was studied using the non-metabolizable amino acid α-aminoisobutyric acid; stimulation was obtained with the highest dose used (90 μg/rat). To test the original somatomedin hypothesis, growth studies were performed in hypophysectomized rats. Two or three doses of met-IGF-I were given with three different administration regimes (i.v. or s.c. infusion, or s.c. injections twice daily) for 6 or 8 days. Little growth-promoting activity was observed, with a significant effect on body weight gain obtained only when met-IGF-I was given continuously at the highest dose used (180 μg/day). No effect was seen on the in-vivo uptake of radioactive sulphate into cartilage. Epiphyseal cartilage width increased slightly at the highest dose of met-IGF-I, but only when the hormone was given by infusion. When 180 μg met-IGF-I/day were given by injections, a significant effect on longitudinal bone growth was obtained (90 μm above control). The levels of IGF in the serum were not measurably increased after s.c. administration of met-IGF-I, whereas after i.v. infusion, significantly raised levels were obtained at the higher dose rates (3·0 ± 0·3 and 2·8 ± 0·1 units/ml). Growth hormone was much more effective than met-IGF-I even at 50-fold lower doses.
Priming the animals with 10 mu. bovine GH/day followed by combined infusions of GH and met-IGF-I did not reveal any potentiating effects of met-IGF-I in the presence of GH. We conclude that met-IGF-I is a relatively poor growth-promoting agent when given systemically, and that somatomedins are more likely to act as local growth factors rather than as circulating mediators of the growth-promoting effects of GH.
J. Endocr. (1987) 112, 123–132
Dissociation between the ovarian factors controlling sexual receptivity and preovulatory secretion of LH in cyclic female rats
Authors: Södersten P. , Eneroth P. 
Published: December 2008

ABSTRACT
Ovariectomy and treatment with oestradiol benzoate (10 μg OB) on the day before behavioural oestrus eliminated the preovulatory surge of LH and reduced the level of sexual receptivity on the following day. Sexual behaviour, but not the LH surge, was restored by progesterone (0·5 mg) given 18 h later. Injection of OB on the day after behavioural oestrus induced a small release of LH and normal sexual behaviour on the following day. Ovariectomy on the day after behavioural oestrus reduced the stimulatory effect of OB on sexual behaviour and eliminated its weakly stimulatory effect on LH release. Sexual behaviour, but not the small LH surge, was restored in these animals by progesterone (0·5 mg) given 18 h later. Treatment of rats ovariectomized 2 days before the day of the LH surge with implants containing oestradiol or injections of oestradiol (1 μg) induced LH surges but the amplitudes of these LH surges were much smaller than those of the normal LH surge. Treatment of intact rats with OB increased serum progesterone levels 24 h later, an effect which was eliminated by ovariectomy. Injections of LH (20 μg) into intact rats on the day after behavioural oestrus also increased serum progesterone concentrations but failed to stimulate sexual behaviour. It is suggested that OB treatment of intact rats on the day after behavioural oestrus stimulates sexual behaviour by inducing a surge of LH secretion which activates ovarian secretion of progesterone. Thus, oestrogen and progesterone but not the LH surge are essential for sexual behaviour. Whereas oestradiol and progesterone restore normal sexual behaviour in ovariectomized rats, additional ovarian factors may be required for induction of normal LH surges.
J. Endocr. (1987) 112, 133–138
Interference of dimethyl α-(dimethoxyphosphinyl) p-chlorobenzyl phosphate (SR-202) in thyroid hormone. metabolism: evidence of inhibition of monodeiodination
Authors: Liniger C. , Pometta D. , Burger A. G. 
Published: December 2008

ABSTRACT
SR-202 is a non-iodinated potential lipid-altering agent. When administered (100 mg) three times per day for 3 days to six euthyroid subjects it was associated with a 30 ± 3% (mean ± s.e.m.) fall in 3,3′,5-tri-iodothyronine(T3)(P < 0·001), a reciprocal 104 ± 14% rise in 3,3′,5′-tri-iodothyronine (reverse T3, rT3) (P < 0·01), and a 37 ± 7% rise in thyroxine (T4) (P < 0·001). Basal and TRH-stimulated TSH did not change. These results suggested that SR-202 was acting as an inhibitor of the peripheral monodeiodination of T4 to T3.
During a second study the same subjects received the same dose of SR-202 for a further 3 days following 15 days of progressive substitutive treatment with l-T4, which they continued to take at 200 μg/day until the end of the study. Despite higher levels of thyroid hormones in the substituted subjects, similar results were observed, serum T3 falling by 40 ± 2% (P < 0·001), serum rT3 and T4 rising by 168 ± 24% (P < 0·01) and 37 ± 9% (P < 0·01) respectively. These changes provide compelling evidence that SR-202 is an inhibitor of the peripheral conversion of T4 to T3 that acts on thyroid hormone metabolism without provoking a counter-regulatory pituitary response. It might prove to be a useful tool for the clinical investigation of thyroid function.
J. Endocr. (1987) 112, 171–175
Influence of the cryptorchid testis on the regeneration of rat Leydig cells after administration of ethane dimethane sulphonate
Authors: Risbridger G. P. , Kerr J. B. , de Kretser D. M. 
Published: December 2008

ABSTRACT
Leydig cells were selectively eliminated from the testis by treatment with the cytotoxin, ethane dimethane sulphonate. Rats were then made unilaterally cryptorchid and the morphological and functional response of the interstitial tissue in abdominal compared with scrotal testes was examined for up to 8 weeks. Regeneration of new Leydig cells occurred more rapidly in the interstitial tissue of abdominally cryptorchid testes compared with the interstitial tissue of contralateral scrotal testes. More rapid recovery of Leydig cells was coincident with significant increases in the bioactivity of a local factor(s), collected from interstitial fluid of cryptorchid testes, which stimulated testosterone production by isolated Leydig cells in vitro. These results support the theory that the production of a local factor(s) plays a role in the regeneration of Leydig cells and is affected by damage to the seminiferous epithelium.
J. Endocr. (1987) 112, 197–204
Identification, properties and effect of hormones on rat preputial gland peroxidase
Authors: De P. K. , Banerjee R. K. 
Published: December 2008

ABSTRACT
A highly active soluble peroxidase has been identified in the preputial glands of the rat. The enzyme was detectable in the sebaceous secretion of the glands and showed catalytic properties characteristic of true peroxidase. It had a native molecular weight of around 73 000 as determined by gel-permeation studies. Immunologically the enzyme cross-reacted with an antiserum against bovine lactoperoxidase. Administration of progesterone resulted in a significant increase in the total activity of the enzyme, while testosterone and oestradiol had no such effect. The enzyme had a similar molecular weight and similar catalytic and immunological properties to rat uterine fluid peroxidase but differed markedly in respect to sensitivity to oestradiol.
J. Endocr. (1987) 112, 239–245
Effect of a non-viral fraction of acquired immunodeficiency syndrome plasma on the vulnerability of lymphocytes to cortisol
Authors: Klein A. , Bruser B. , Robinson J. B. , Pinkerton P. H. , Malkin A. 
Published: December 2008

ABSTRACT
We have observed previously that the rate of cortisol catabolism by lymphocytes (CCL) was indicative of the vulnerability of these cells to cortisol. We attempted to ascertain whether cortisol-sensitive lymphocytes (e.g. thymocytes) metabolize cortisol at a different rate from cortisol-resistant cells and whether lymphocytes in which cortisol catabolism is inhibited become cortisol sensitive. The work was facilitated by the observation that an ethanol extract plasma from patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC) had the capacity to inhibit CCL.
The capacity of thymocytes to metabolize cortisol was found to be 11 times lower than that of peripheral lymphocytes. Inhibition of CCL with an ethanol extract of plasma from AIDS/ARC patients made the cells vulnerable to cortisol, causing them to die at a rate seven times greater than that of control samples. It is suggested that these findings may have important implications with regard to the nature of lymphocyte depletion in AIDS/ARC patients or in people at risk of developing the syndrome.
J. Endocr. (1987) 112, 259–264
Inhibition of post-partum maternal behaviour in the rat by injecting an oxytocin antagonist into the cerebral ventricles
Authors: van Leengoed E. , Kerker E. , Swanson H. H. 
Published: December 2008

ABSTRACT
Endogenous oxytocin released into the brain at parturition may stimulate the onset of maternal behaviour. In this study an attempt was made to block spontaneous maternal behaviour following natural delivery in Wistar rats by the injection of an antagonist of oxytocin into the cerebral ventricles. The analogue antagonist, d(CH2)5-8-ornithine-vasotocin, was administered by injection into a chronically implanted cannula in the right lateral ventricle at hourly intervals, beginning immediately after the expulsion of the first pup. The antagonist did not interfere with the normal progress of parturition or birth-related behaviours.
After delivery of the last pup, mothers rested for 40 min in the test cage with the pups having been removed. Four pups and standard nesting material were then presented. Latency to pup carrying and duration of pup manipulation, nest building, and time spent on the nest with the pups, as well as duration of autogrooming and general activity were determined. Saline-injected controls started gathering the pups immediately and usually showed all elements of maternal behaviour within 10 min. Antagonist-treated mothers showed a marked delay in the onset of pup grouping and other maternal behaviours. At the end of 1 h, two out of six mothers had not yet picked up a single infant. Pups left overnight with their mothers were gathered into the nest and suckled, and no long-term effects of the antagonist were evident on retesting.
The effectiveness of oxytocin antagonist in suppressing the rapid onset of post-partum maternal behaviour supports the hypothesis that centrally released oxytocin is involved in this process. It is noteworthy that these effects were obtained in Wistar rats, a strain in which oxytocin has failed to accelerate responsiveness to pups in virgin females.
J. Endocr. (1987) 112, 275–282
Endocrine and behavioural factors affecting water balance in sheep subjected to isolation stress
Authors: Parrott R. F. , Thornton S. N. , Forsling M. L. , Delaney C. E. 
Published: December 2008

ABSTRACT
The effect of stress on drinking, water balance and endocrine profile was studied using ten castrated rams. Individual sheep were exposed to 30-h periods of total isolation (psychological stress) or physical separation from their social group (control). Plasma was analysed for haematocrit, osmolality, electrolyte levels and concentrations of cortisol and arginine vasopressin. Isolation stress significantly reduced water intake, increased haematocrit and plasma concentration of cortisol, but did not alter osmolality or vasopressin concentration. The physiological effects of this self-imposed water restriction contrast with those obtained by depriving the sheep of water for 24 h under conditions that were not stressful, i.e. by keeping them grouped together. These results suggest that cortisol may act to defend plasma volume in sheep exposed to acute stress. The results also indicate that vasopressin probably should not be considered to be a 'stress hormone' in the sheep.
J. Endocr. (1987) 112, 305–310
Production and metabolic clearance of angiotensinogen in conscious rats as measured by steady-state isotope dilution
Authors: Little M. H. , Sernia C. 
Published: December 2008

ABSTRACT
Previous studies on the hormonal regulation of hepatic angiotensinogen relied on in-vitro liver preparations and on the measurement of changes in plasma concentration. In this study 125I-labelled angiotensinogen was used to measure simultaneously the production rate (PR) and metabolic clearance rate (MCR) in conscious rats by the constant-rate infusion and single-injection methods. Male rats received daily s.c. injections of isotonic saline (as control), 1 mg corticosterone acetate (CA), 25 μg 17β-oestradiol benzoate (OB) or 20 μg thyroxine (T4) per 100 g body weight. On day 7 of treatment 125I-labelled angiotensinogen was infused into a jugular vein at a rate of 1 μl/h by osmotic minipumps and blood samples taken 4, 5 and 6 days later. The PR of angiotensinogen increased from 576 ± 28 (s.e.m.; n = 9) to 954 ± 63 (n = 9), 1010±84 (n = 9) and 2359±150 (n = 10) μg/h per kg following treatment with CA, OB and T4 respectively. In contrast, the PR of rat albumin did not change significantly from 218 ± 8 (n = 7) mg/h per kg. All three hormones increased MCR from 13 ± 1 (n = 17) ml/h per kg to 17± 1 (n = 9), 18 ± 2 (n = 9) and 27 ± 2 (n = 9) ml/h per kg for CA, OB and T4 respectively. Single-injection experiments on five rats showed angiotensinogen to be distributed into three compartments with a half-time of disappearance of 4·4 ± 1 min, 116±11 min and 13·1 ±2·6 h. It was concluded that the production of angiotensinogen in vivo is at least tenfold higher than the reported in-vitro rates, that the clearance of angiotensinogen is under hormonal regulation and that angiotensinogen is distributed between at least three compartments.
J. Endocr. (1987) 112, 391–397
Pancreatic somatostatin, glucagon and insulin during post-hatch growth in the duck (Anas platyrhynchos)
Authors: Foltzer Ch. , Harvey S. , Mialhe P. 
Published: December 2008

ABSTRACT
Pancreatic somatostatin-like immunoreactivity (SLI), immunoreactive insulin (IRI) and glucagon-like immunoreactivity (GLI) were measured during growth in ducks. The content of each hormone increased progressively but at different rates in the dorsal, ventral and splenic lobes of the pancreas. In the almost fully grown duck, the splenic lobe contained 80 and 63% of the total content of GLI and SLI respectively but low levels of IRI (23%), which were highest in the dorsal lobe (53%). In contrast to the hormonal content, only total GLI concentrations increased during development, the SLI concentrations remaining stable and IRI concentrations declining during growth. Gel filtration of pancreatic extracts indicated that most of the SLI in the pancreas of young and adult birds was somatostatin-14, although somatostatin-28 was present in the ventral lobe of young birds and larger molecular forms were present in the ventral and dorsal lobes. These changes in pancreatic hormonal content and concentration are dissimilar to age-related changes in SLI, GLI and IRI previously observed in the plasma of ducks. Plasma levels of pancreatic hormones may thus be controlled by hormonal and/or neural factors during post-hatch growth.
J. Endocr. (1987) 113, 65–70
Serotoninergic regulation of corticosterone secretion in domestic fowl
Authors: Cheung A. , Hall T. R. , Harvey S. 
Published: December 2008

ABSTRACT
The effects of serotoninergic drugs on adrenocortical function in domestic fowl were examined. Administration of the serotonin receptor agonist 2-(1-piperazinyl)quinoline maleate (quipazine), an inhibitor of serotonin metabolism, N-methyl-N-2-propynylbenzylamine HCl (pargyline), as well as serotonin itself, all increased plasma concentrations of corticosterone. The maximum responses to serotonin and quipazine occurred 1 h after treatment. The quipazine-stimulated response was partly prevented by the serotonin antagonist cyproheptadine. Cockerels pretreated with dexamethasone, a synthetic steroid known to inhibit pituitary ACTH release, showed attenuated responses to subsequent quipazine, pargyline or serotonin injection. Serotonin, quipazine and cyproheptadine did not affect corticosterone release directly from the adrenal gland incubated in vitro, nor did they affect adrenal responsiveness to ACTH stimulation. The neurotoxin 5,6-dihydroxytryptamine injected into day-old chicks decreased plasma concentrations of corticosterone for up to 7 days after treatment, with corresponding decreases in the hypothalamic concentration of serotonin, but not dopamine or noradrenaline concentrations. These results show that adrenal corticosterone secretion is regulated by a central serotoninergic system, probably acting on the hypothalamo-pituitary-adrenal axis.
J. Endocr. (1987) 113,159–165
Effect of sialoadenectomy, treatment with epidermal growth factor (EGF) antiserum and replacement of EGF on the epidermis in mice
Authors: Tsutsumi O. , Kubota Y. , Oka T. 
Published: December 2008

ABSTRACT
Epidermal growth factor (EGF) was present at a mean concentration of 266±18 (s.e.m.) pmol/mg wet tissue in the submandibular gland of 3-month-old male mice; it was also present in plasma at a concentration of 364±149 pmol/l. Sialoadenectomy (removal of the submandibular glands) decreased the plasma EGF content to undetectable levels (< 16·5 pmol/l), lowered the concentration of EGF in the skin from 1·22±0·11 to 0·47±0·08 fmol/mg wet tissue and reduced the thickness of the epidermis from 28·9±2·7 to 11·0±0·8 μm in 3 weeks (P < 0·001). Epidermal growth factor antiserum given to sialoadenectomized mice further decreased the thickness of the epidermis to 8·3 ±0·6 μm. No appreciable change was observed in the dermis and subcutaneous tissue. In sialoadenectomized mice, replacement of EGF prevented the decrease in thickness of the epidermis in a dose-dependent manner when started immediately after the operation. Treatment with EGF also effectively restored the normal morphology of the epidermis when its thickness had declined to its lowest level. These results suggest that EGF plays a physiological role in the maintenance of the epidermis.
J. Endocr. (1987) 113, 193–197