Effects of hypophysectomy and subsequent FSH and testosterone treatment on inhibin production by adult rat testes

1985 ◽  
Vol 105 (1) ◽  
pp. 1-6 ◽  
Author(s):  
C. L. Au ◽  
D. M. Robertson ◽  
D. M. de Kretser
Keyword(s):  
Seminiferous Tubule ◽  
Hormonal Control ◽  
Human Chorionic Gonadotrophin ◽  
Experimental Conditions ◽  
Adult Rats ◽  
Adult Rat ◽  
Fluid Production ◽  
Tubule Fluid

ABSTRACT The hormonal control of inhibin production by adult rat testes was investigated using an in-vitro inhibin bioassay validated for the measurement of inhibin activity in charcoal-treated rat testicular extracts. The effect of hypophysectomy examined at 16 h, 3, 7 and 42 days after surgery showed a decrease in testicular inhibin content and seminiferous tubule fluid production by 7 days and a decrease in inhibin production by 42 days. Serum FSH and LH were suppressed 3 days after surgery. In 30-day chronically hypophysectomized adult rats treated for 3 days with twice daily s.c. injections of (a) human FSH (hFSH, 22 i.u./rat per day), (b) testosterone (5 mg/rat per day), (c) hFSH + testosterone (same doses as a and b), or (d) human chorionic gonadotrophin (hCG, 12 i.u./rat per day), hFSH or hFSH and testosterone stimulated an increase in testicular inhibin content but not in inhibin production or tubule fluid production. Testosterone and hCG had no effect on these parameters. It is concluded that in vivo, FSH alone stimulates an increase in testicular inhibin content. The failure to observe an increase in inhibin production in vivo is attributed to the suppression of seminiferous tubule fluid production under the same experimental conditions. J. Endocr. (1985) 105, 1–6

Ethan-1,2-dimethanesulphonate reduces testicular oxytocin content and seminiferous tubule movements in the rat

1987 ◽  
Vol 112 (2) ◽  
pp. 311-NP ◽  
Author(s):  
H. D. Nicholson ◽  
R. T. S. Worley ◽  
S. E. F. Guldenaar ◽  
B. T. Pickering
Keyword(s):  
Leydig Cell ◽  
Seminiferous Tubule ◽  
Leydig Cells ◽  
Contractile Activity ◽  
Histological Study ◽  
Interstitial Cells ◽  
Seminiferous Tubules ◽  
Adult Rats ◽  
Adult Rat

ABSTRACT An oxytocin-like peptide is present in the interstitial cells of the testis, and testicular concentrations of oxytocin have been shown to increase seminiferous tubule movements in vitro. We have used the drug ethan-1,2-dimethanesulphonate (EDS), which depletes the Leydig cell population of the adult rat testis, to examine further the relationships between the Leydig cell, testicular oxytocin and tubular movements. Adult rats were injected i.p. with a single dose of EDS (75 mg/kg) or of vehicle (25% dimethyl sulphoxide). Histological study 3 and 10 days after treatment with EDS showed a reduction in the number of interstitial cells, and levels of oxytocin immunoreactivity were undetectable by radioimmunoassay. Immunostaining revealed very few oxytocin-reactive cells. Spontaneous contractile activity of the seminiferous tubules in vitro was also dramatically reduced, but could be restored by the addition of oxytocin to the medium. Four weeks after EDS treatment, the interstitial cells were similar to those in the control animals both in number and in immunostaining; immunoassayable oxytocin was present and tubular movements were normal. The EDS effect, seen at 3 and 10 days, was not altered by daily treatment with testosterone. However, repopulation of the testes with oxytocin-immunoreactive cells was not seen until 6 weeks in the testosterone-treated animals. We suggest that the Leydig cells are the main source of oxytocin immunoreactivity in the testis and that this oxytocin is involved in modulating seminiferous tubule movements and the resultant sperm transport. The results also imply that testosterone does not play a major role in controlling tubular activity in the mature rat. J. Endocr. (1987) 112, 311–316

Postovulatory steroidogenesis after PMS-induced ovulation in immature female rats

1981 ◽  
Vol 241 (3) ◽  
pp. E221-E225 ◽  
Author(s):  
K. Taya ◽  
G. S. Greenwald
Keyword(s):  
Serum Levels ◽  
Female Rats ◽  
Corpora Lutea ◽  
Adult Rats ◽  
Rat Serum ◽  
Follicular Maturation ◽  
Adult Rat ◽  
Serum Lh

Thirty-day-old rats given a single subcutaneous injection of 5 IU pregnant mare serum gonadotropin (PMS) at 0900 h ovulated on the morning of day 33 (= estrus). However, the second ovulation did not occur until 9.4 days later. To determine the mechanism responsible for the delay in the second ovulation, in vivo and in vitro determinations of steroid and peptide hormones were compared between PMS-primed immature rats and adult cyclic rats. In PMS-primed rats, the corpora lutea (CL) produced progesterone for 2 days longer (until day 36) than the CL of the adult rat. Serum levels of 20 alpha-dihydroprogesterone, testosterone, and estradiol in PMS-primed rats were significantly lower than the corresponding values in adult rats. Serum LH was consistently lower in the PMS-primed rats. An increase in serum FSH occurred on days 36–37, which may be responsible for maturation of the follicles destined to ovulate at the second ovulation. On day 37, the nonluteal ovary of the PMS-primed rats also began to produce in vitro appreciable amounts of testosterone and estradiol. These findings suggest that the greater levels of prolactin and/or low levels of luteinizing hormone during estrus in PMS-primed rats may be responsible for the prolonged secretion of progesterone by the CL. This in turn inhibits follicular maturation, indirectly by lowering serum LH, which is reflected in reduced ability of the follicles in vitro to produce testosterone and estradiol until the CL regress.

Local Circuit Properties Underlying Cortical Reorganization

2002 ◽  
Vol 88 (3) ◽  
pp. 1288-1301 ◽  
Author(s):  
Peter W. Hickmott ◽  
Michael M. Merzenich
Keyword(s):  
Cortical Reorganization ◽  
The Novel ◽  
Adult Rats ◽  
Postsynaptic Potentials ◽  
Local Circuit ◽  
Adult Rat ◽  
The Times ◽  
Stimulation Of

Peripheral denervation has been shown to cause reorganization of the deafferented somatotopic region in primary somatosensory cortex (S1). However, the basic mechanisms that underlie reorganization are not well understood. In the experiments described in this paper, a novel in vivo/in vitro preparation of adult rat S1 was used to determine changes in local circuit properties associated with the denervation-induced plasticity of the cortical representation in rat S1. In the present studies, deafferentation of rat S1 was induced by cutting the radial and median nerves in the forelimb of adult rats, resulting in a rapid shift of the location of the forepaw/lower jaw border; the amount of the shift increased over the times assayed, through 28 days after denervation. The locations of both borders (i.e., original and reorganized) were marked with vital dyes, and slices from the marked region were used for whole-cell recording. Responses were evoked using electrical stimulation of supragranular S1 and recorded in supragranular neurons close to either the original or reorganized border. For each neuron, postsynaptic potentials (PSPs) were evoked by stimulation of fibers that crossed the border site (CB stim) and by equivalent stimulation that did not cross (NCB stim). Monosynaptic inhibitory postsynaptic potentials (IPSPs) were also examined after blocking excitatory transmission with 15 μM CNQX plus 100 μMdl-APV. The amplitudes of PSPs and IPSPs were compared between CB and NCB stimulation to quantify effects of the border sites on excitation and inhibition. Previous results using this preparation in the normal (i.e., without induced plasticity) rat S1 demonstrated that at a normal border both PSPs and IPSPs were smaller when evoked with CB stimulation than with NCB stimulation. For most durations of denervation, a similar bias (i.e., smaller responses with CB stimulation) for PSPs and IPSPs was observed at the site of the novel reorganized border, while no such bias was observed at the suppressed original border site. Thus changes in local circuit properties (excitation and inhibition) can reflect larger-scale changes in cortical organization. However, specific dissociations between these local circuit properties and the presence of the novel border at certain durations of denervation were also observed, suggesting that there are several intracortical processes contributing to cortical reorganization over time and that excitation and inhibition may contribute differentially to them.

Correlation between the activity of liver enzymes and the LD50 of parathion in the rat

1970 ◽  
Vol 48 (12) ◽  
pp. 829-831 ◽  
Author(s):  
J.-G. Alary ◽  
J. Brodeur
Keyword(s):  
Adult Male ◽  
Liver Enzymes ◽  
Female Rats ◽  
Experimental Conditions ◽  
Adult Rats ◽  
In Vitro Degradation ◽  
Male And Female ◽  
Male And Female Rats

A study was undertaken to investigate a possible correlation between the acute LD50 of parathion, in weanling and adult male and female rats, and the activity of the liver enzymes involved in the in vitro metabolism of parathion and its toxic oxygen analogue, paraoxon. A close relationship was found in adult male and female rats, as well as in adult females pretreated with phenobarbital, between the LD50 and the rate of in vitro degradation of parathion by the liver under experimental conditions in which both oxidative and hydrolytic metabolism occur. On the same basis, immature rats appeared to be more sensitive to parathion than was to be expected from the ability of their livers to metabolize parathion in vitro. It is concluded that the rate of in vitro degradation of parathion by the liver is a satisfactory index of the in vivo toxicity of parathion in adult rats, but not in immature animals.

Abstract 15601: On the Mechanisms of Accelerated Calcification of Bioprosthetic Heart Valve Biomaterials in Juvenile Animal Models

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Yingfei Xue ◽  
Alexander Kossar ◽  
Gaetano THIENE ◽  
Robert LEVY ◽  
Giovanni Ferrari
Keyword(s):  
Pediatric Patients ◽  
Calcium Deposition ◽  
Collagen Structure ◽  
Adult Rats ◽  
Rat Serum ◽  
Juvenile Rats ◽  
Adult Rat ◽  
Circulating Markers

Objective: Bioprosthetic heart valves (BHV) are subject to accelerated structural valve degeneration (SVD) in pediatric patients. Prior literature has reported differences in circulating markers of mineralization in pediatric patients compared to adults. Here we test the hypothesis that calcification-related circulating markers are differentially expressed in juvenile vs adult animals, and these markers functionally drive the accelerated SVD in juvenile animals in vitro and in vivo . Methods: Serum calcium (Ca 2+ ), phosphate (PO 4 - ), alkaline phosphatase (ALP), and osteopontin (OPN) levels of juvenile (3 week-old; n=5) and adult (8 month-old; n=5) Sprague-Dawley rats were measured by commercially-available assay kits. Glutaraldehyde-fixed bovine pericardial discs (BP) were incubated in juvenile or adult rat serum in vitro for 4 or 8 weeks. BP were subcutaneously implanted in juvenile or adult rats for 7 or 30 days (4-6 discs/rat). Pericardial transcatheter valves were implanted in juvenile Dorset sheep for 150 days (n=3). Alizarin Red staining, Von Kossa staining, and a quantitative assay were used for calcium analyses. Second harmonic generation imaging visualized collagen structure. Results: Serum Ca 2+ (p<0.05), PO 4 - (p<0.05), ALP (p<0.01), and OPN (p<0.01) were all increased in juvenile rats compared to adult rats. BP incubated in juvenile rat serum resulted in higher calcium deposition (p<0.05) and more disruption to collagen structure as evidenced by reduced alignment coefficient (p<0.01) as compared to those incubated in adult rat serum. Similarly, BP explanted from juvenile rats had higher calcium deposition (p<0.01) and more disrupted collagen structure in terms of collagen alignment and crimp period (p<0.01). Results in progress in juvenile sheep implantation model further confirmed the in vitro and in vivo findings that BHV explants had substantial calcium deposition and collagen disalignment. Conclusion: Calcium accumulates within BHV biomaterials more prominently in juvenile rats; increased serum markers of mineralization may explain the increased susceptibility to SVD in pediatric patients. Future studies will investigate novel strategies for the prevention and mitigation of accelerated SVD in pediatric patients.

scholarly journals Effects of KiSS-1 Peptide, the Natural Ligand of GPR54, on Follicle-Stimulating Hormone Secretion in the Rat

Endocrinology ◽  
2005 ◽  
Vol 146 (4) ◽  
pp. 1689-1697 ◽  
Author(s):  
V. M. Navarro ◽  
J. M. Castellano ◽  
R. Fernández-Fernández ◽  
S. Tovar ◽  
J. Roa ◽  
...  
Keyword(s):  
Excitatory Amino Acid ◽  
Hormone Secretion ◽  
Metastasis Suppressor ◽  
Experimental Conditions ◽  
Adult Rats ◽  
Gonadotropin Secretion ◽  
Neuroendocrine Control

Abstract KiSS-1 was originally identified as a metastasis suppressor gene encoding an array of structurally related peptides, namely kisspeptins, which acting through the G protein-coupled receptor GPR54 are able to inhibit tumor progression. Unexpectedly, a reproductive facet of this newly discovered system has recently arisen, and characterization of the role of the KiSS-1/GPR54 system in the neuroendocrine control of gonadotropin secretion has been initiated. However, such studies have been so far mostly restricted to LH, and very little is known about the actual contribution of this system in the regulation of FSH release. To address this issue, the effects of KiSS-1 peptide on FSH secretion were monitored in vivo and in vitro under different experimental conditions. Intracerebroventricular administration of KiSS-1 peptide significantly stimulated FSH secretion in prepubertal and adult rats. Yet, dose-response analyses in vivo demonstrated an ED50 value for the FSH-releasing effects of KiSS-1 of 400 pmol, i.e. approximately 100-fold higher than that of LH. In addition, systemic (ip and iv) injection of KiSS-1 significantly stimulated FSH secretion in vivo. However, KiSS-1 failed to elicit basal FSH release directly at the pituitary level, although it moderately enhanced GnRH-stimulated FSH secretion in vitro. Finally, mechanistic studies revealed that the ability of KiSS-1 to elicit FSH secretion was abolished by the blockade of endogenous GnRH actions, but it was persistently observed in different models of leptin insufficiency and after blockade of endogenous excitatory amino acid and nitric oxide pathways, i.e. relevant signals in the neuroendocrine control of gonadotropin secretion. In summary, our results extend previous recent observations on the role of KiSS-1 in the control of LH secretion and provide solid evidence for a stimulatory effect of KiSS-1 on FSH release, acting at central level. Overall, it is proposed that the KiSS-1/GPR54 system is a novel, pivotal downstream element in the neuroendocrine network governing gonadotropin secretion.

scholarly journals Glutamine gluconeogenesis in the small intestine of 72 h-fasted adult rats is undetectable

2006 ◽  
Vol 401 (2) ◽  
pp. 465-473 ◽  
Author(s):  
Guy Martin ◽  
Bernard Ferrier ◽  
Agnès Conjard ◽  
Mireille Martin ◽  
Rémi Nazaret ◽  
...  
Keyword(s):  
Small Intestine ◽  
Glucose Production ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Concentration Difference ◽  
Adult Rat ◽  
Nutrition And Diabetes ◽  
Glucose Synthesis

Recent reports have indicated that 48–72 h of fasting, Type 1 diabetes and high-protein feeding induce gluconeogenesis in the small intestine of adult rats in vivo. Since this would (i) represent a dramatic revision of the prevailing view that only the liver and the kidneys are gluconeogenic and (ii) have major consequences in the metabolism, nutrition and diabetes fields, we have thoroughly re-examined this question in the situation reported to induce the highest rate of gluconeogenesis. For this, metabolically viable small intestinal segments from 72 h-fasted adult rats were incubated with [3-13C]glutamine as substrate. After incubation, substrate utilization and product accumulation were measured by enzymatic and NMR spectroscopic methods. Although the segments utilized [13C]glutamine at high rates and accumulated 13C-labelled products linearly for 30 min in vitro, no substantial glucose synthesis could be detected. This was not due to the re-utilization of [13C]glucose initially synthesized from [13C]glutamine. Arteriovenous metabolite concentration difference measurements across the portal vein-drained viscera of 72 h-fasted Wistar and Sprague–Dawley rats clearly indicated that glutamine, the main if not the only gluconeogenic precursor taken up, could not give rise to detectable glucose production in vivo. Therefore we challenge the view that the small intestine of the adult rat is a gluconeogenic organ.

Comparison of the effects on purified Leydig cells of four hormones (oxytocin, vasopressin, opiates and LHRH) with suggested paracrine roles in the testis

1987 ◽  
Vol 113 (1) ◽  
pp. 89-96 ◽  
Author(s):  
R. M. Sharpe ◽  
I. Cooper
Keyword(s):  
Leydig Cells ◽  
Interstitial Fluid ◽  
Adult Rats ◽  
Adult Rat ◽  
Clear Cut ◽  
Testosterone Production ◽  
Time Period ◽  
High Doses

ABSTRACT Four hormones have been identified by various authors as possible paracrine regulators of testicular Leydig cells. The aim of this study was to evaluate their effects on purified adult rat Leydig cells under various conditions in vitro, and then to assess whether comparable effects occurred in vivo. In agreement with previous findings, an LHRH agonist (LHRH-A) exerted clear-cut effects on testosterone secretion by Leydig cells both in vitro and in vivo. On its own, LHRH-A stimulated testosterone production by Leydig cells for up to 24 h in culture but inhibited testosterone production stimulated by human chorionic gonadotrophin (hCG) between 24 and 72 h of culture. In-vivo, unilateral intratesticular injection of adult rats with 1 ng LHRH-A resulted 5 h later in a significant increase in testosterone concentrations in testicular interstitial fluid (IF). Vasopressin exerted effects in vitro which were similar to those of LHRH-A. On its own, vasopressin stimulated testosterone production for up to 5 h of culture, but not thereafter, while in the presence of hCG, vasopressin inhibited testosterone production beyond 24 h of culture. The initial stimulatory effect of vasopressin on testosterone production occurred with concentrations of 1 nmol/l and higher, but the magnitude of stimulation (threefold or less) was considerably less than that induced by LHRH-A (ninefold) over the same time period. In contrast to LHRH-A, unilateral intratesticular injection of vasopressin in high doses (20 and 2 ng) had no effect on IF testosterone levels 5 h later. When Leydig cells were cultured in the presence of testicular IF, to approximate in-vivo conditions, there was marked stimulation of testosterone production, but the effects of vasopressin and LHRH-A in the presence of IF were comparable to those observed in its absence. Neither morphine nor oxytocin at concentrations of 0·1 μmol/l had any effect on testosterone production under any of the conditions of culture, and unilateral intratesticular injection of oxytocin, morphine or naloxone was without effect on the IF levels of testosterone. It is concluded that opiates and oxytocin are probably not involved in the paracrine regulation of Leydig cells, whereas vasopressin may play such a role. However, as the stimulatory effects of vasopressin were small in relation to those of LHRH-A and were not evident in vivo, the physiological significance of the effects of vasopressin are uncertain. J. Endocr. (1987) 113, 89–96

Degradation of IGF-I in the adult rat gastrointestinal tract is limited by a specific antiserum or the dietary protein casein

1995 ◽  
Vol 146 (2) ◽  
pp. 215-225 ◽  
Author(s):  
C J Xian ◽  
C A Shoubridge ◽  
L C Read
Keyword(s):  
Receptor Binding ◽  
Dietary Protein ◽  
Half Life ◽  
Structural Integrity ◽  
Binding Activity ◽  
Adult Rats ◽  
Adult Rat ◽  
Igf I

Abstract To investigate the potential of IGF-I peptides as therapeutics in the gut, the survival profiles of a bolus of 125I-labelled IGF-I (8·6 ng) in vivo in various ligated gut segments of fasted adult rats have been examined. The intactness of IGF-I tracer in the flushed luminal contents was estimated by trichloroacetic acid precipitation, antibody and receptor binding assays. It was found that IGF-I was degraded very rapidly in duodenum and ileum segments with a half-life (t1/2) of 2 min by all three methods. IGF-I was slightly more stable in the stomach (t1/2=8, 5 and 2·5 min by the above three methods), and considerably more stable in the colon (t1/2=38, 33 and 16 min as judged by the three methods). Rates of degradation in gut flushings in vitro were similar to the in vivo rates except for the colon, where IGF-I was proteolysed more rapidly in vivo. As a means of developing gut-stable and active forms of IGF-I, several approaches were examined for their effectiveness in prolonging IGF-I survival in the upper gut. It was found that the extension peptide on the analogue, LR3IGF-I did not protect IGF-I, nor did association with IGF-binding protein-3. However, an IGF-I antiserum was effective in prolonging IGF-I half-life in duodenum fluid by 28-fold. Charge interaction between IGF-I and heparin could also protect IGF-I in the stomach but not in duodenum flushings. Furthermore, casein (a non-specific dietary protein) and to a lesser extent, BSA and lactoferrin, were effective in preserving IGF-I structural integrity and receptor binding activity in both stomach and duodenum fluids. It can be concluded that IGF-I cannot be expected to retain bioactivity if delivered orally because of rapid proteolysis in the upper gut, but the use of IGF antibodies and casein could represent useful approaches for IGF-I protection in oral formulae. Journal of Endocrinology (1995) 146, 215–225

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