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PubMed2002

Effects of local anaesthesia or local anaesthesia plus a non-steroidal anti-inflammatory drug on the acute cortisol response of calves to five different methods of castration.

The cortisol response of calves to different methods of castration (ring, band, surgical, clamp) with or without local anaesthetic, or local anaesthetic plus a non-steroidal anti-inflammatory drug were recorded. All methods of castration caused a significant cortisol response and by inference pain and distress. Band castration caused a greater cortisol response than ring castration but the responses were eliminated by local anaesthetic. The cortisol response to surgical castration, by traction on the spermatic cords or by cutting across them with an emasculator, was not diminished by local anaesthetic but when ketoprofen was given with local anaesthetic the cortisol response was eliminated. Local anaesthetic did reduce the behavioural response to cutting the scrotum and handling the testes. Clamp castration caused the smallest cortisol response which was reduced or eliminated by local anaesthetic or local anesthetic plus ketoprofen respectively, but this method of castration was not always successful.

Anesthetics, Local↗
PubMed2003

Involvement of calcitonin gene-related peptide in elevation of skin temperature in castrated male rats.

OBJECTIVES: To assess the involvement of calcitonin gene-related peptide (CGRP) in the occurrence of hot flashes in men after castration for treatment of prostate cancer, we investigated the effects of CGRP on skin temperature in surgically and medically castrated male rats. METHODS: Changes in skin temperature of the hind paws after intravenous injection of 10 microg/kg of CGRP and CGRP family peptides (adrenomedullin and amylin) were measured at 5-minute intervals for 120 minutes, 3 weeks after bilateral orchiectomy or 2 weeks after subcutaneous injection of a gonadotropin-releasing hormone analogue (1.0 mg/kg Leuplin) in male rats. Antagonism with CGRP8-37 (1000 microg/kg intravenously), a CGRP1 receptor antagonist, to the CGRP-induced response was examined by injecting it 10 minutes before injection of CGRP. The effect of testosterone replacement on castration was evaluated in each castrated rat by the administration of testosterone (1.0 mg/kg subcutaneously once a day) for 14 days before the day of the temperature analysis. RESULTS: CGRP, but not adrenomedullin and amylin, elevated the skin temperature in surgical or medical castration-induced testosterone-deficient rats more than in the sham-treated rats. The difference was statistically significant. The CGRP-induced potentiation in the castrated rats was inhibited by pretreating with CGRP8-37 or by supplying testosterone. CONCLUSIONS: CGRP is the most potent peptide in a family that elevates the skin temperature in male rats. The elevation of the skin temperature was more affected by the testosterone deficiency resulting from castration. These results suggest that CGRP is involved in the mechanism underlying hot flashes in men.

Adrenomedullin↗
PubMed1995

Single-agent therapy with bicalutamide: a comparison with medical or surgical castration in the treatment of advanced prostate carcinoma.

OBJECTIVES: Single-agent therapy with bicalutamide, a nonsteroidal antiandrogen, was compared with castration, either surgical or medical, in patients with untreated Stage D2 prostate cancer. METHODS: In an open, randomized, multicenter trial, patients were randomized to treatment with 50 mg bicalutamide (n = 243) once daily or to castration (n = 243), either orchiectomy or depot injection of goserelin acetate every 28 days. Primary efficacy endpoints were times to treatment failure and objective disease progression and survival. Assessments included review of measurable metastases, prostate dimensions, Eastern Cooperative Oncology Group performance status, pain, analgesic requirements, and quality of life responses. RESULTS: The median duration of therapy was 39 weeks for bicalutamide-treated patients and 42 weeks for castrated patients; treatment failure occurred in 53% and 42% and disease progression in 43% and 33%, respectively. Treatment effects favored castration for both endpoints (P < or = 0.002), with hazard ratios (bicalutamide:castration) of 1.54 (95% confidence interval [CI], 1.18 to 2.00) for time to treatment failure and 1.6 (95% CI, 1.19 to 2.15) for time to disease progression. From the 1-year survival analysis, the hazard ratio for probability of death was 1.29 (95% CI, 0.96 to 1.72). Thus far, with a median follow-up of 86 weeks, median survival has not been reached in either group. Changes from baseline in several quality of life variables were significantly different (P < or = 0.01) between treatment groups periodically from months 1 to 6, and all favored bicalutamide. Overall, the antiandrogen was well tolerated compared with castration; with bicalutamide, hot flushes occurred less often and breast tenderness and gynecomastia more often. CONCLUSIONS: Although a dosage of 50 mg of bicalutamide once daily was not as effective as castration, the favorable quality of life outcomes and the low incidence of nonhormonal adverse events provide reasons to evaluate bicalutamide, as a single therapeutic agent, at higher doses.

Aged↗
PubMed1996

Effect of castration on the VIPergic innervation and 125I-labelled vasoactive intestinal peptide (VIP) binding sites in the hamster seminal vesicle. A quantitative immunohistochemical and receptor autoradiographic study.

In the present work we have investigated the effects of medium- (15 days) and long-term (2 months) castration on vasoactive intestinal peptide (VIP)-immunoreactive nerve fibres and 125I-labelled VIP binding sites in the adult hamster seminal vesicle. The density of VIP- and synaptophysin (general neuronal marker)-containing nerve fibres was determined in immunofluorescently stained cryostat sections using a computerised image analysis system. The morphological analysis of 125I-VIP binding sites in seminal vesicle cryostat sections was performed by quantitative receptor autoradiography. Our results show that the densities of the overall (synaptophysin immunoreactive) and VIPergic innervation increase in both medium and long-term castrated animals. In absolute terms, the quantity of VIP- and synaptophysin- containing nerves is not altered in medium-term castrates, but decreases for synaptophysin in long-term castrates. Medium-term castration does not affect the density of 125I-VIP binding sites in the gland muscular coat, but a significant decrease is observed after long-term castration. In conclusion, our results indicate that whereas VIP nerves are apparently unaffected by castration, 125I-VIP binding sites in the muscular coat of hamster seminal vesicle are sensitive to androgen levels.

Animals↗
PubMed2006

Evalution of the castrated male Sprague-Dawley rat as a model of the metabolic syndrome and type 2 diabetes.

OBJECTIVE: Low testosterone levels have been shown to be predictive for the development of the metabolic syndrome in men. The aim of this study was to describe effects of testosterone deficiency on metabolic syndrome-related parameters in male rats in order to evaluate the rat as a model for the human metabolic syndrome related to low testosterone levels. METHODS: Male Sprague-Dawley rats were castrated or sham operated at 16 weeks of age and fed either a standard or a high energy diet. Measured parameters were: food intake, body weight, fat distribution, energy expenditure, physical activity and blood/plasma parameters related to glucose and lipid metabolism. RESULTS: Castration led to an increase in the amount of subcutaneous fat, but did not result in any changes in the visceral fat. Fasting blood glucose levels were increased and free fatty acids concentration decreased in the castrated rats from 2 weeks after castration and throughout the study, whereas no significant differences between the groups were found in any of the other parameters measured. A high-energy diet did not change the response to castration in male Sprague-Dawley rats. CONCLUSION: Compared to humans rats respond differently to testosterone deficiency. Only few of the features typical for the human metabolic syndrome were observed in castrated male Sprague-Dawley rats. Therefore, we conclude that with the present experimental setup the castrated rat is not an optimal model for studies on the influence of testosterone deficiency on body fat distribution and the development of other central components of the metabolic syndrome.

Adipose Tissue↗
PubMed1997

Effects of castration on adrenergic, cholinergic and nonadrenergic, noncholinergic responses of isolated corpus cavernosum from rabbit.

OBJECTIVE: To investigate the effects of castration and testosterone on the constricting effect of phenylephrine and endothelium-dependent and -independent relaxing effects of different agonists in the corpus cavernosum of male rabbits. MATERIALS AND METHODS: Twenty rabbits were castrated and 10 received testosterone replacement for 1 month after castration; 10 further rabbits underwent a sham operation and acted as controls. One month after operation the rabbits were killed and their penises excised. Strips of corpus cavernosum were used for isometric tension measurements in organ chambers; concentration-response relationships for phenylephrine, carbachol, adenosine and sodium nitroprusside were obtained by adding the reagent cumulatively to the bath. RESULTS: The phenylephrine-induced contractions were markedly lower, with no change in the pD2 values (i.e. the negative logarithm of the concentration for half-maximal response), in cavernosal strips obtained from castrated rabbits than in those from controls. Endothelium-dependent relaxation elicited by carbachol increased in the castrated group but the relaxation induced by sodium nitroprusside did not change and those elicited by adenosine were strongly depressed when compared with controls. There were no significant changes in the pD2 values of agonist-induced relaxation responses in all groups. The relaxation elicited by electrical-field stimulation at lower frequencies increased in strips from castrated rabbits but at higher frequencies were unchanged when compared with controls. Castration-induced changes in the relaxation response of cavernosal strips were significantly restored by in vivo testosterone replacement but those induced by phenylephrine were not. CONCLUSION: The lack of testosterone has an effect on the reactivity of the corpus cavernosum, indicating that testosterone has an important role in erectile function by a pre- or post-synaptic action on the corpus cavernosum.

Adenosine↗
PubMed2004

The fate of the medically castrated testis: expectation versus reality.

PURPOSE: Cosmetic expectation has a major role in influencing patient choice between medical and surgical castration, and yet to our knowledge the fate of the medically castrated testis has never been accurately tested and documented in the literature. We determined the weight of testes in patients receiving medical castration and compared it to that in a control group receiving primary surgical castration. MATERIALS AND METHODS: We performed a retrospective analysis of 88 patients with prostate cancer who underwent bilateral simple orchiectomy with epididymal sparing. The study was done at Veterans Administration Medical Center, Atlanta, Georgia. All procedures were performed using local anesthesia in an outpatient clinical setting. Patients were divided into 2 groups, namely 52 receiving luteinizing hormone releasing hormone (LH-RH) agonist therapy prior to the procedure and 36 controls who were not. The weight of the testes was compared between the 2 groups. RESULTS: Median testicular weight significantly decreased following treatment with LH-RH agonist compared to the control group. Median weight of the testis was 7.0 gm (range 0.5 to 22.0) in the LH-RH agonist group compared to 15 gm (range 4.0 to 44.0) in the control group (p = 0.0049 x 10). CONCLUSIONS: Medical castration with LH-RH agonist therapy significantly decreases the weight of testes and compromises the cosmetic outcome. Since cosmetic expectation has a major role in influencing patient choice between medical and surgical castration, patients should be fully informed about the significant testicular atrophy associated with medical castration before making their decision.

Androgen Antagonists↗
PubMed2006

Effects of castration on cannabinoid cb receptor expression and on the biological actions of cannabinoid in the parotid gland.

In the present study, we examined whether cannabinoid receptor expression and the effects of receptor stimulation vary as a function of gonadal status in a peripheral tissue, namely the male rat parotid gland. Four groups of male rats were studied: gonadal intact, castrated, castrated testosterone (1 mg/100 g bodyweight) treated and gonadal intact testosterone treated. 2. The results showed that the density of CB(1) receptors decreased after castration and that receptor density was restored to control values after testosterone treatment. This decrement was associated with a decrease of anandamide (10(-10) to 10(-5) mol/L)-induced cAMP accumulation and amylase release without changes in the anandamide-induced inhibition of Na(+)/K(+)-ATPase activity. 3. Castration did not modify either the subtype of cannabinoid receptor involved in the actions of anandamide or drug affinity for the receptor. 4. The mechanism underlying anandamide-induced cAMP accumulation, amylase release and inhibition of Na(+)/K(+)-ATPase activity, namely through the activation of adenylyl cyclase, was the same in control and castrated rats. 5. Basal cAMP accumulation, amylase release and Na(+)/K(+)-ATPase activity were not altered by castration. 6. Castration had no effect on the concentration of total protein. 7. It can be concluded that CB(1) cannabinoid receptor expression is regulated by testosterone in male rat parotid gland and this has functional implications for cAMP accumulation and amylase release.

Adenosine Triphosphatases↗
PubMed1986

Stress in calves castrated surgically or by the application of rubber rings.

The effects of castration were studied in calves 4 to 11 weeks of age, using increases in salivary cortisol as an indicator of stress. Groups were castrated surgically or by rubber ring application or were non-castrated (control) females. The surgically castrated group showed more agitation during the operation, but both castrated groups resumed normal behaviour soon after the operation was completed. The short-term salivary cortisol response was significantly higher after surgical castration than after the application of rubber rings, where, in turn, it was significantly higher than in the control group. Salivary cortisol was elevated over a period from 15 min to 3 h following the castration, but at 4, 24 h and 6 days post-treatment there were no significant differences between treated groups and controls.

Animals↗
PubMed1993

Production, behaviour and fertility of merino wethers, hemi-castrates with reduced testicular parenchyma and induced cryptorchids.

Greasy wool production, body weight, behaviour and fertility of male, fine wool Merino sheep were studied from 10 to 21 months of age to assess their suitability for wool production. The males were either castrated (wethers), or were hemi-castrated with a vasectomy and reduction (either partially or in full) of the parenchyma of the retained testicle, or the testicles pushed up into the inguinal canal and the scrotum shortened (induced cryptorchids). There were significant differences among all groups in body weight, with increases being associated with the larger amounts of testicular tissue present. Fertility was low in the induced cryptorchids at 19 months of age. The hemi-castrates with reduced testicular parenchyma were infertile. The hemi-castrates with reduced testicular parenchyma had significantly heavier greasy fleece weights than the wethers and induced cryptorchids, which had similar fleece weights. The wether group suffered a higher prevalence of posthitis in spring and autumn than the hemi-castrate or induced cryptorchid groups. Those hemi-castrates with the largest amount of testicular parenchyma retained and the induced cryptorchids exhibited masculine behaviour patterns and had an increased incidence of fly strike to the head. The principle of hemi-castration and reduction of the testicular parenchyma is shown to be applicable in wool producing flocks with the potential to increase greasy wool production while minimising the management and marketing limitations previously associated with induced cryptorchids.

Animals↗
PubMed1999

Equine castration: review of anatomy, approaches, techniques and complications in normal, cryptorchid and monorchid horses.

Complications associated with equine castration are the most common cause of malpractice claims against equine practitioners in North America. An understanding of the embryological development and surgical anatomy is essential to differentiate abnormal from normal structures and to minimise complications. Castration of the normal horse can be performed using sedation and regional anaesthesia while the horse is standing, or under general anaesthesia when it is recumbent. Castration of cryptorchid horses is best performed under general anaesthesia at a surgical facility. Techniques for castration include open, closed and half-closed techniques. Failure of left and right testicles to descend occurs with nearly equal frequency, however, the left testicle is found in the abdomen in 75% of cryptorchid horses compared to 42% of right testicles. Bilateral cryptorchid and monorchid horses are uncommon. Surgical approaches described for the castration of cryptorchid horses include an inguinal approach with or without retrieval of the scrotal ligament, a parainguinal approach, or less commonly a suprapubic paramedian or flank approach. Laparoscopic castration of cryptorchid horses has recently been described but the technique has limited application in practice at this time. A definitive diagnosis of monorchidism can only be made after surgical exploration of the abdomen, removal of the normal testis and hormonal testing. Hormonal assays reported to be useful include analysis of basal plasma or serum testosterone or oestrone sulphate concentrations, testosterone concentrations following hCG stimulation, and faecal oestrone sulphate concentrations. Reported complications of castration include postoperative swelling, excessive haemorrhage, eventration, funiculitis, peritonitis, hydrocele, penile damage and continued stallion-like behaviour.

Animals↗
PubMed1996

Glycosaminoglycans in the three lobes of the rat prostate following castration and testosterone treatment.

Androgen dependence of glycosaminoglycans (GAGs) in the prostate was studied using tissue from intact (sham control), castrated, and androgen-treated castrated rats. GAGs from the ventral, dorsal, and lateral lobes of the prostate were isolated and characterized by cellulose electrophoresis using appropriate GAG standards and enzymatic digestion or nitrous acid hydrolysis. Androgen deprivation was initiated by castration and rats were sacrificed at various time intervals after 7 days castration. After castration, the total GAG content decreased in three prostate lobes. At day 7 after castration, the total hyaluronic acid (HA) content decreased by 74% (ventral lobe) and 34% (lateral lobe) compared with the sham control. No effect was observed for HA content in the dorsal lobe. Castration decreased the total heparan sulphate (HS), dermatan sulphate (DS), and chondroitin sulphate (CS) contents in the three prostate lobes at 0 days of treatment, except for the CS content in the dorsal and lateral lobes. Androgen replacement increased the total GAG contents in the three prostate lobes. At 14 days of testosterone propionate treatment, there were 9-, 6.8-, 4.1- and 3.7-fold increases in HA, HS, DS, and CS, respectively, in the ventral lobe. These increases were more rapid and profound in the ventral than in the dorsal and lateral lobes. These findings indicate that all GAGs are regulated by androgen and there may be lobe-specific differences in their regulation. This could be a function of the heterogeneous populations of cells in each lobe.

Animals↗
PubMed2003

Improved erectile function after Rho-kinase inhibition in a rat castrate model of erectile dysfunction.

Androgens are reported to act as strong modulators of erectile function influencing both nitric oxide and vasoconstrictor signaling. Castration results in a depressed erectile response that is associated with a loss of nitric oxide production and increased responsiveness to constrictive agents. The increased vasoconstrictor response may be a result of an active RhoA/Rho-kinase signaling pathway. We report here results of studies designed to test the hypothesis that inhibition of the Rho-kinase pathway restores erectile function in a castrate model by relaxing the smooth muscle. Mean arterial (MAP) and corpus cavernosal (CCP) pressures were monitored during intracavernosal injection of the Rho-kinase inhibitor Y-27632. Castration reduced the maximal erectile response (CCP/MAP) by 33%, and testosterone replacement restored the response (intact, 0.736 +/- 0.040; castrate, 0.492 +/- 0.022; testosterone, 0.681 +/- 0.073). Injection of Y-27632 increased CCP in all experimental groups; it also left shifted the voltage response curve and increased the maximal CCP/MAP response (intact, 0.753 +/- 0.091; castrate, 0.782 +/- 0.081; testosterone treated, 0.894 +/- 0.033). Y-27632 dose dependently relaxed phenylephrine-stimulated cavernosal tissues. Cavernosal tissues showed increased RhoA and Rho-kinase protein levels after castration. Our data support the hypothesis that an active Rho/Rho-kinase pathway contributes to the reduced erectile response after castration due to an upregulation of RhoA/Rho-kinase protein levels and that inhibition of this pathway may serve as an effective treatment for erectile dysfunction.

Amides↗
PubMed2002

Different effects of castration and estrogen administration on glomerular injury in spontaneously hyperglycemic Otsuka Long-Evans Tokushima Fatty (OLETF) rats.

AIM: Non-insulin-dependent diabetic mellitus model rats, Otsuka-Long-Evans-Tokushima-Fatty (OLETF), develop diabetic nephropathy presenting with mesangial expansion leading to glomerular sclerosis and thickening of the glomerular basement membrane (GBM), especially in elderly males. The effects of sex hormones and castration on the incidence of diabetes mellitus (DM) have been studied in this strain rat. However, there have been no detailed studies on the effects of castration and sex hormone in the development of diabetic nephropathy. METHODS: In this study we examine the effect of castration or estrogen on the development of glomerular injury in OLETF rats. Thirty male OLETF rats and 10 male long-Evans Tokushima Otsuka (LETO) rats as a normal control were used. OLETF rats were divided into three groups: group 1 received sham-operation, group 2 was castrated at 6 weeks, and group 3 was administered 0.1 mg estrogen subcutaneously once a month from 6 weeks to 58 weeks of age and LETO rats were assigned to group 4. Body weight, urinary protein and fasting blood glucose, serum albumin and other serum constituents were investigated every 12 weeks from 12 weeks to 60 weeks of age. In groups 1-3, glucose tolerance test was performed at 38 weeks. Each group was studied morphologically at the end of the experiment (60 weeks of age). RESULTS: Castration attenuated proteinuria and glomerular sclerosis accompanied by an amelioration of glucose tolerance, a decrease in mesangial expansion and an attenuation of the GBM thickening. In contrast, although estrogen equally ameliorated glucose tolerance and attenuated the mesangial expansion and the GBM thickening, estrogen failed to attenuate proteinuria and glomerulosclerosis. A significant increase in glomerular tuft volume, and serum levels of growth hormone, total cholesterol and triglycerides was observed in the estrogen-treated rats as compared with the castrated rats. CONCLUSION: Besides the mechanisms involved in the development of diabetic nephropathy, other mechanisms may be involved and contribute to the development of glomerulosclerosis in the estrogen-treated rats, leading to a difference in glomerular injury between the castrated and estrogen-treated OLETF rats.

Animals↗
PubMed2002

Profiles of in vivo gamma-aminobutyric acid release in the medial preoptic area of intact and castrated male rats.

We have suggested that gamma-aminobutyric acid (GABA) in the hypothalamus plays a tonic inhibitory role in the control of the luteinizing hormone (LH) release in intact male rats. To assess whether feedback from the testis alters the inhibitory GABAergic tone in the medial preoptic area (MPO) of male rats, an in vivo microdialysis study was performed in gonadally intact (n = 10), castrated (n = 12) and castrated testosterone-primed (n = 10) male rats. The microdialysis samples were collected and sequential blood samples were also obtained at 1-hour intervals. GABA in the dialysate was determined by high-performance liquid chromatography system and serum LH concentration was determined by radioimmunoassay. Episodic GABA release in the MPO was observed in all three groups of male rats, although castrated male rats showed lower GABA release (2.3 +/- 0.3 ng/h) than intact and castrated testosterone-primed male rats (4.0 +/- 0.5 and 4.6 +/- 1.0 ng/h, respectively). Conversely, castrated male rats showed higher serum LH concentration (7.31 +/- 0.46 ng/ml) than intact and castrated testosterone-primed male rats (0.71 +/- 0.04 and 0.53 +/- 0.07 ng/ml, respectively). In addition, intravenous infusion of bicuculline significantly increased serum LH in intact male rats, whereas bicuculline did not alter serum LH concentrations in castrated male rats. These results are consistent with the hypothesis that the feedback of testosterone stimulates GABA release in the region of the GnRH cell bodies and dendrites in male rats.

Animals↗
PubMed1986

A scanning electron-microscopic study of femoral bone surfaces from castrate rats treated with dichloromethylene biphosphonate.

This study compared SEM appearances of endosteal and periosteal surfaces of anorganic femoral diaphyses from three groups of adult male rats: (1) control; (2) castrate (osteoporotic), and (3) castrate + injections of dichloromethylene biphosphonate (Cl2 entrances; (2) area of vascular canal entrances; (3) number of osteoblast lacunae, and (4) percent area of bone surface types. Endosteal surfaces from untreated osteoporotic rats had significantly more osteoblast lacunae, larger vascular canal entrances, and less resting surface than those of the other groups. There were no differences in endosteal surfaces between controls and Cl2MBP-treated castrates. Periosteal surfaces demonstrated no significant differences in percent area of bone surface types between groups, untreated castrates had more osteoblast lacunae than other groups, and vascular canal entrances were smaller in castrate groups than in controls. Castrates treated with Cl2MBP had significantly fewer periosteal vascular canal entrances, and many canal entrances and osteoblast lacunae appeared to be plugged with mineral deposits when compared with the other groups. The results indicate that Cl2MBP treatment prevented endosteal bone surface changes that occurred with castration osteoporosis, and may have disrupted normal vascularization on periosteal surfaces.

Animals↗
PubMed1993

Castration attenuates proteinuria and glomerular injury in hyperlipidemic male Imai rats.

Hyperlipidemic Imai rats spontaneously develop proteinuria and glomerulosclerosis, especially in males. We investigated the effect of castration on spontaneous proteinuria and progressive renal injury in male Imai ats. Male Imai rats (n = 16) were castrated at 5 weeks of age. Body weight, blood pressure, urinary protein excretion and serum constituents were checked and compared with sham-operated control rats (n = 16) up to 24 weeks. Sham-operated group 1 (n = 5) and castrated group 2 (n = 6) underwent morphological study after 16 weeks of observation and sham-operated group 3 (n = 11) and castrated group 4 (n = 10) were followed for an additional 8 weeks and used for morphological study. Growth rate was significantly stunted in castrated rats as compared with the controls. Castration significantly reduced proteinuria almost throughout the experiment (167 +/- 84 vs. 46 +/- 24 mg/kg/day, p < 0.001, at 8 weeks and 688 +/- 211 vs. 458 +/- 97, p < 0.01, at 20 weeks). The glomerulosclerosis index was significantly higher in sham-operated control rats than in castrated rats (28.8 +/- 18.0 vs. 7.3 +/- 3.1, p < 0.01, at 16 weeks, and 92.1 +/- 35.5 vs. 39.5 +/- 8.9, p < 0.001, at 24 weeks). There were no significant differences in blood pressure, serum cholesterol, plasma renin activity, plasma somatomedin C levels between the two groups. These results raise the possibility that sex hormones may partly contribute to spontaneous proteinuria and progressive renal injury in male Imai rats.

Animals↗
PubMed1987

Neuropeptide Y levels in microdissected regions of the hypothalamus and in vitro release in response to KCl and prostaglandin E2: effects of castration.

Intracerebroventricular administration of neuropeptide Y (NPY) has been shown to modify LH secretion, with the direction of the response dependent on the steroid background. To study further the role of gonadal steroids in the regulation of NPY secretion, the basal and KCl-evoked release of NPY from the medial basal hypothalamus (MBH) of intact and castrated male rats was assessed twice with the use of an in vitro incubation system. In each experiment, the amounts of NPY released in response to a 15-min pulse of KCl (45 mM) were significantly smaller from the MBH of castrated rats than of intact rats (P less than 0.05). Next, to assess the possible effects of prostaglandin E2 (PGE2), the MBH were exposed in a similar manner to two 15-min pulses, 30 min apart, of 0.568 and 56.8 mumol PGE2. Unlike KCl, PGE2 failed to stimulate NPY release from the MBH of either intact or castrated rats. However, a similar 56.8 mumol concentration of PGE2 was effective in stimulating the release of LHRH. We next examined the effects of castration on NPY levels in several microdissected regions of the hypothalamus. Whereas NPY concentrations were unchanged in the medial preoptic area, paraventricular nucleus and dorsomedial nucleus, NPY levels were significantly decreased in the median eminence, arcuate nucleus, and ventromedial nucleus 2 weeks after castration. These studies show that KCl can stimulate NPY release from the MBH in vitro, like that of LHRH, the KCl-induced NPY response is significantly smaller from the MBH of castrated than intact males, castration can significantly reduce the levels of NPY in the median eminence, arcuate nucleus, and ventromedial nucleus, thereby suggesting that testicular secretions may modulate NPY levels and release from the MBH, and because PGE2 stimulated the release of LHRH but not of NPY, separate regulatory neural events may underlie the secretion of these two neuropeptides.

Animals↗