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PubMed1980

Effect of adrenalectomy or castration on the inhibition of gonadotrophin secretion induced by hyperprolactinaemia in the adult male rat.

To investigate the role of adrenal and gonadal steroids in the long-term suppression of gonadotrophin secretion induced by prolactin the effects of adrenalectomy or castration on the serum and pituitary levels of LH, FSH and prolactin and the hypothalamic content of LH releasing hormone (LH-RH) have been studied in adult male rats with hyperprolactinaemia produced by the transplantation of pituitary glands under the kidney capsule. Levels of LH and FSH in serum were significantly suppressed in al intact pituitary-grafted rats. Adrenalectomy on the day of pituitary implantation or 20 days later did not affect the suppression. However, castration on days 0, 28 or 49 after pituitary grafting resulted in a rise in levels of FSH in serum indistinguishable from that in control rats. While the rise in levels of LH after castration on day 0 was the same as the controls, this increase was significantly reduced 2 days after castration on days 28 and 49 after pituitary grafting. Castration resulted in an increase in the pituitary content of LH and a reduction in the hypothalamic content of LH-RH but no change in the pituitary content of FSH. Hyperprolactinaemia did not appear to affect these response. The present results showed clearly that the gonad but not the adrenal must be present for prolactin to exert an inhibitory effect on gonadotrophin secretion.

Adrenalectomy↗
PubMed1980

Role of the gonads in the regulation of sebaceous glands in rats: comparison of the effects of castration at and after birth.

Sprague-Dawley rats were castrated either within 24 h of birth or at 4 weeks of age. Control animals were sham operated. Intact female rats were also included for comparison. Sebum production was assessed at 80 days of age by measuring the amount of skin-surface lipids that could be extracted with acetone and which had been produced during 2 days. The removal of the testes at birth reduced the activity of the sebaceous glands to level more nearly approaching that seen in the female rats whereas castration at 4 weeks of age only partially decreased the rate of sebum secretion so that it was intermediate between the male and female rats. The weights of the pituitary gland, thyroid and adrenal glands increased after castration but there were no differences between rats castrated at birth and those castrated at 4 weeks of age except in the weight of the thyroid gland. It would appear that the role of the testes in the control of the activity of the sebaceous glands is a sequential event which has already started at birth.

Animals↗
PubMed1982

Photoperiodic modulation of gonadotrophin secretion in castrated Japanese quail.

Male Japanese quail were castrated when sexually immature and immediately exposed to one of the following stimulatory lighting regimes for 52 days: 11 h light: 13 h darkness/day (11L : 13D), 12L : 12D, 13L : 11D, 14L : 10D, 15L : 9D, 16L : 8D, 20L : 4D or 23L : 1D. One group was retained on short days (8L : 16D). Clearcut differences in the plasma levels of LH and FSH emerged between the various groups. Levels remained very low in castrated quail on 8L : 16D but were much greater in those on 14L : 10D, 15L : 9D, 16L : 8D, 20L : 4D and 23L : 1D, eventually becoming 15 to 20 times higher. Less pronounced castration responses developed on 13L : 11D, 12L : 12D or 11L : 13D. Alterations in photoperiod after day 52 caused an appropriate rise or fall in LH secretion. Photoperiodically induced suppressions were rapid, being highly significant within 4 days, but increases usually had a slower time course. When sexually mature quail (on 16L : 8D) were castrated and transferred to 8L :16D they also exhibited a rapid suppression in LH secretion. Thus in quail, unlike some mammals, the photoperiodic control over gonadotrophin secretion is independent of the reproductive status of the animal at the time of castration. The results confirm the view that changes in sensitivity of the hypothalamo-pituitary axis to gonadal steroids are not a primary factor in the neural mechanisms underlying photoperiodism in quail.

Animals↗
PubMed1982

Pubertal development of the boar: testosterone, estradiol-17 beta, cortisol and LH concentrations before and after castration at various ages.

Forty-eight Landrace x Duroc boars were assigned at weaning to eight castration ages (40, 70, 100, 130, 160, 190, 220 and 250 d). Catheterization of the external jugular vein was performed 5 d before scheduled castration. Blood samples were collected every .5 h between 0800 and 1200 h, 2 d before (-2) and on d +1, +2, +3, +4, +8 and +16 after castration. Testosterone (T) was determined in serum samples collected every .5 h on d -2. Serum concentrations of estradiol-17 beta (E2), cortisol (C) and luteinizing hormone (LH) were quantified by radioimmunoassays in pooled (within boar) samples collected on d -2. In addition, LH was determined in pooled (within boar) samples collected on d +1, +2, +3, +4, +8 and +16 after castration. Mean concentrations of T and E2 (d -2) increased in a near linear (P less than .01) fashion with age of boar. However, T concentrations at 250 d of age had declined (P less than .01) to values similar to concentrations of boars at 130 d of age. Serum C concentrations (d -2) were lower (P less than .01) at 100, 130 and 160 d of age compared with an average C concentration of 19 ng/ml for all other age groups. Mean concentrations of LH (d -2) did not differ among any of the ages. Luteinizing hormone concentrations were elevated (P less than .01) within 1 to 2 d following castration at 40, 70, 100, 130 and 160 d of age. Serum T concentrations of individual boars varied greatly at all ages as determined by half-hourly sampling over a 4-h period. The results indicate that in the boar: (1) T concentrations increase as pubertal development progresses and decline as maturity nears; (2) E2 concentrations increase steadily through pubertal development; (3) C concentrations are depressed at 100, 130 and 160 d of age relative to concentrations before and after that period; (4) LH concentrations are constant during pubertal development, and (5) a decrease in the sensitivity of the negative feedback mechanism controlling LH occurs after 160 d of age.

Aging↗
PubMed1985

Some effects of photoperiod on the pituitary/thyroid axis of castrated cockerels.

Pituitary cyclic adenosine monophosphate-dependent protein kinase (cAMP-PK) activity ratios of castrated cockerels on a short photoperiod are highest 2 weeks after testosterone removal in castrated birds and remain high through a 3rd week. Castrated cockerels on long photoperiods have a decline in cAMP-PK activity ratios after an elevation at 1 week following testosterone removal. This is interpreted to mean that the pituitaries of cockerels on short photoperiods are sensitive to testosterone inhibition but that this sensitivity disappears in long photoperiod-stimulated birds. Long daylengths also appear to enhance thyroid activity in castrated cockerels, although thyroid cAMP-PK activity ratios increase in the thyroid of all cockerels following the removal of testosterone (castration). These results suggest that testosterone has an inhibitory effect on both the pituitary and thyroid glands.

Animals↗
PubMed2005

Catch-up in body weight of intrauterine growth retarded (IUGR) rats castrated and treated with growth hormone.

The aim of the present study was to assess body weight recovery in rats with intrauterine growth retardation (IUGR) castrated and treated with growth hormone (GH). Wistar albino rats were divided into the following experimental groups: control (C), sham-operated (SH), IUGR, IUGR castrated (IUGR+C), and IUGR castrated and injected with GH (IUGR+C+GH). IUGR was induced by partial bending of uterine vessels at day 14 of pregnancy. GH (Genotropin 3.0 mg/kg/day) was administered from weaning (21 days old) to 60 days of age. SH rats were injected only with diluent. Castration was performed at weaning. Body weight, body weight velocity and relative food intake were registered weekly. Data were analyzed by ANOVA and LSD post hoc test. The between-subjects analysis showed significant differences for sex and treatment factors. Differences in body weight were significant among treatments, being SH > IUGR > IUGR+ C+GH > IUGR+C in males, and SH > IUGR+C > IUGR+C+GH > IUGR in females. Differences in relative food intake were IUGR+C > IUGR+C+GH > IUGR > SH in males, and IUGR+C+GH > IUGR+C > IUGR > SH in females. These results indicate that nutritional rehabilitation impairs the effects of IUGR. While the absence of testosterone inhibited body weight gain, the absence of estrogens promoted catch-up growth. Castrated animals with or without GH treatment ate relatively more, suggesting the absence of an anabolic effect of gonadal steroids.

Animals↗
PubMedDate not supplied

Effect of cyproterone acetate in comparison to flutamide on the ventral prostate of adult male castrated Copenhagen-Fisher rats and on Dunning R-3327 H tumors.

In this investigation the effect of CPA was tested in comparison to FL after the procedure of double blinding on the ventral prostate of 70 adult male castrated Copenhagen-Fisher rats and on the Dunning R-3327 H tumor. Total androgen blockade by castration plus CPA or by castration plus FL induced significant decrease in prostate weight compared to the androgen deprivation by castration alone. No significant difference between CPA and FL was observed. Furthermore it was impossible to exaggerate this effect with higher doses of CPA of FL. The Dunning R-3327 H tumor did not become palpable 60 days after inoculation of the tumor cells indicating that androgen deprivation by total androgen blockade by castration plus CPA or plus FL did not exhibit any proliferative activity on the hormone-sensitive Dunning R-3327 H tumor cells.

Androgen Antagonists↗
PubMed1989

[Towards a veterinary-professional standard concerning castration in stallions].

Complications following castration are increasingly often regarded as unacceptable by the owners of horses. A veterinary surgeon can only be held responsible for the consequences of his professional procedure when castration is not performed according to the rule (lege artis), i.e. if the surgeon failed to act in accordance with professional veterinary standards. So far, there is no consensus concerning the standard regarding the castration of stallions as various techniques are being used, and as some veterinary surgeons consider complications to be a normal risk in surgery. Visceral prolapse should be considered to be the most serious complication, particularly following 'open' castration. Although exact data are not available, it is the impression of the present authors that the incidence of intestinal evisceration and inguinal hernia in stallions is increasing in the Netherlands. When high priority is given to the prevention of evisceration, the 'open' method of castration should be abandoned. To reduce the hazard of evisceration to a minimum, the (half)closed technique, which involves crushing and ligation of the spermatic cord enclosed in the vaginal tunic, is recommended. This procedure enhances the risk of wound infection and scirrhous cord. However, these complications may be reduced when a high degree of asepsis is maintained during surgery.

Animals↗
PubMed1986

The time-course of contractions induced by acetylcholine and barium in the vas deferens of normal and castrated guinea-pigs.

1. The influence of castration on contraction of the guinea pig vas deferens induced by acetylcholine was investigated regarding facilitation of endogenous neurotransmitter release, changes in post-synaptic events and modification in acetylcholine metabolization. 2. Castration prolonged the duration of the isometric contraction of the vas deferens induced by acetylcholine (3 mM) but not the duration of that induced by barium chloride (10 mM). 3. Reserpinization (0.5 mg/kg) of normal and castrated guinea pigs did not change the time-course of acetylcholine-induced contraction in the vas deferens. 4. 4-Aminopyridine (0.05 mM) prolonged the contraction induced by acetylcholine and barium chloride. This effect was blocked by reserpine pretreatment, indicating that in the presence of 4-AP, both acetylcholine and barium release endogenous noradrenaline. Since there was no difference between the effects of 4-AP on organs from normal and castrated animals, prolongation of the acetylcholine-induced contraction is not related to an increase in neutransmitter release. 5. Total cholinesterase and acetylcholinesterase activities were reduced after castration and the time-course of carbachol contraction was not changed. Thus, this decrease in enzyme activity appears to play a relevant role in the prolongation of acetylcholine-induced contraction.

Acetylcholine↗
PubMed1985

Effect of prepubertal versus postpubertal castration on sexual and aggressive behavior in male horses.

Males horses castrated prepubertally occasionally display stallion-like sexual and aggressive behavior as adults. A retrospective survey of 140 horse owners was undertaken to compare the effectiveness of prepubertal versus postpubertal castration on objectionable sexual and aggressive behavior. Of 94 geldings that had been castrated prepubertally (before 2 years of age), 20% to 30% displayed stallion-like sexual behavior and aggression toward horses, and 5% were aggressive toward people in a stallion-like manner. This occurrence of problem behavior was not significantly different from the occurrence of these behavioral patterns in 46 geldings that had been castrated as stallions (over 3 years of age). When castration was examined as a therapeutic measure to eliminate sexual and aggressive behavior in stallions in which the behavior had become objectionable, it was found that the operation was effective on sexual behavior and aggression toward people in 60% to 70% of horses and on aggression toward horses in 40% of horses.

Aggression↗
PubMed1985

[Effects of sex steroid hormones on vascular reactivity to angiotensin II in castrated rat].

The vascular reactivity to exogenous angiotensin-II (A-II) was blunt in castrated rats treated with estrogen alone or with estrogen plus progesterone. To study the effect of the steroids on vascular reaction to A-II, the plasma renin activity (PRA), plasma aldosterone concentration (PAC) and prostanoids concentration were determined in castrated rats treated with sex steroid hormones. In castrated rats treated with estradiol benzoate, PRA and 6-keto PGF1 alpha were significantly higher than those of untreated rats. On the other hand, PAC in castrated rat treated with progesterone was significantly higher than that in untreated rats. And no significant difference in mean arterial pressure under anesthesia was found between the castrated rats and hormone-treated rats. These findings suggest that rats treated with estradiol benzoate alone or with estradiol benzoate plus progesterone remain in a normotensive state in spite of high PRA, as a compensatory mechanism of decreased vascular reactivity and a vasodilatory prostaglandin may be involved in the regulation of vascular reactivity to A-II in rats treated with estradiol benzoate or with estradiol benzoate plus progesterone.

Alprostadil↗
PubMed1979

Partial inhibition of castration-induced involution in rat prostate by chloroquine. A preliminary observation.

The effect of chloroquine phosphate, a membrane stabilizing agent, on castration-induced involution in the prostate was investigated in adult Sprague-Dawley rats. Chloroquine phosphate (75 mg per kg of body weight) was administered daily by gastric tube on 4 consecutive days beginning 1 day before castration. Control rats received water. All animals were sacrificed 7 days after castration and the ventral prostates were analyzed. The chloroquine group had a mean prostatic weight 17 per cent greater than that of the water-fed control group (P less than 0.01) despite a modest loss in body weight. The activity of cathepsin D, a lysosomal enzyme, in the prostate of treated rats was double that measured in control rats. Histologically, prostates from chloroquine treated rats contained more lysosomal particles that were larger than those from control rats. Serum testosterone reached castrate levels in both groups of animals within 24 hr of castration. These results indicate that it is possible to reduce the rate of prostatic regression by chloroquine, although at a small magnitude, probably through the action of membrane stabilization.

Animals↗
PubMed1979

Maintenance of physiologic concentrations of plasma testosterone in the castrated male dog, using testosterone-filled polydimethylsiloxane capsules.

Effects of various numbers of polydimethylsiloxane (PDS) capsules filled with testosterone (PDS-T) on plasma testosterone (PT) in castrated male dogs were studied. Dogs were implanted with 1 empty PDS capsule or 1, 3, or 5 PDS-T capsules. Blood samples were collected prior to and after implantation, after castration with capsules in situ, and after capsule removal. The PT was determined in these samples by radioimmunoassay. One empty capsule had no effect on PT concentration; after castration, PT values fell to nondetectable amounts. One PDS-T capsule maintained PT at concentrations above nondetectable amounts after castration, but these concentrations were significantly (P less than 0.05) lower than were preimplantation values. Three or five PDS-T capsules were capable of maintaining PT concentrations in the castrated male dog similar to those concentrations seen in the intact dog.

Animals↗
PubMed1979

Quantitative protein changes in the hypothalamic neurons of pubertal male rats, castrated neonatally.

The effect of neonatal castration of male rats on the sexual differentiation of the hypothalamus at puberty was studied. Male rats were castrated on days 1, 5 and 7 after birth. Their brains were processed for study on days 83-85. The neurons and cell nuclei of the preoptic area, mediobasal and ventromedial nuclei were assessed for changes in cell and nuclear sizes and dry weight (calculated using interferometric methods). Neonatal castration resulted in size as well as dry weight increase in the neurons of the anterior and mediobasal hypothalamus. The dry weight increased by 34% (P less than 0.001) in the medial preoptic area, by 25% (P less than 0.001) in the arcuate neurons and by 22% (P less than 0.001) in the ventromedial nucleus. The cell nuclei exhibited perceptible weight increase too--in the medial preoptic area 68% (P less than 0.001); 55% in the arcuate neurons (P less than 0.001), and 39% in the ventromedial region. The weight and size increases in neonatally castrated males were equal to those of females of the same age. In rats castrated on day 7, the cell sizes and dry weights of the ventromedial nucleus increased but the cell nuclei exhibited only little change. It is assumed that the changes in the dry weight may be the result of increased synthetic processes in these groups of neurons which are connected with the tonic and cyclic release of gonadotropins. These changes also point to the hypothalamic differentiation shifting to the female type in the absence of the inducing effect of androgens.

Animals↗
PubMed1984

[Different behavior of the rat vas deferens of castrated animals and those treated with cyproterone acetate].

The effects of castration and treatment with the antiandrogen cyproterone acetate (CPA) on the responses of the vas deferens of the rat induced by phenylephrine, KCl and BaCl2 has been studied. Both castration and CPA induced a spontaneous motility in the rat vas deferens. Castration produces a decrease of the response amplitude induced by phenylephrine and KCl and an increase of those induced by BaCl2 in animals killed 30 days after castration. CPA increases the response amplitude induced by phenylephrine and KCl without modifying those induced by BaCl2. These results suggest that the antiandrogen CPA produces modifications qualitatively different from castration.

Animals↗
PubMed1983

[An inventory of the castration of stallions based on a survey among Dutch veterinarians].

To gain an insight into the procedures adopted in castrating stallions in the Netherlands, a questionnaire was sent to 670 Dutch veterinary practitioners. The 176 veterinary practitioners who replied performed 1850 castrations. Castration of the recumbent horse was preferred by 88 per cent of the veterinary surgeons. Fifty per cent preferred the open method of castration and 44 per cent the half-closed technique. A local anaesthetic was given by 65 per cent of the practitioners; 84 per cent administered antibiotics in an attempt to prevent wound infection. Postoperative complications were observed in 18 per cent of the castrations carried out.

Animals↗
PubMed1980

Effects of castration and chronic morphine administration on liver alcohol dehydrogenase and the metabolism of ethanol in the male Sprague-Dawley rat.

The effects of castration on liver alcohol dehydrogenase (ADH) activity and the in vivo metabolism of ethanol were examined in the male Sprague-Dawley-derived rat. It was found that castration led to immediate (24 hr) increases in the ADH-dependent metabolism of ethanol which persisted for at least 6 weeks postcastration. Testosterone completely reversed the effects of castration. Moreover, when increases in liver ADH activity and the metabolism of ethanol were allowed to develop to maximal levels (2 weeks), a single s.c. injection of testosterone promptly reversed the effects of castration, such that by 24 hr castrated animals were indistinguishable from controls. Thus, it appears that in the male Sprague-Dawley-derived rat liver ADH activity and the in vivo metabolism of ethanol are under the control of testosterone. Because narcotics have also been shown to depress serum testosterone levels, and there is good evidence of significant pharmacological and biochemical interactions between the narcotics and ethanol, we examined whether chronic administration of morphine led to testosterone-reversible increases in the ADH-dependent metabolic disposition of ethanol. We found that chronic morphine administration, at doses sufficient to markedly depress serum testosterone levels (> 85%), produced large increases in liver ADH activity and the clearance of ethanol. Concurrent administration of testosterone completely abolished this effect. These data may, therefore, provide the first evidence of a biochemical mechanism involved in the interactions between morphine and ethanol. Furthermore, our results suggest that drug-induced reductions in serum testosterone may serve as an important mechanism involved in the cross-tolerance observed between ethanol and many abused, sedative-hypnotic drugs which share the common ability to decrease serum testosterone.

Alcohol Oxidoreductases↗
PubMed1982

Effect of castration on the morphology of the motor end-plates of the rat levator ani muscle.

The levator ani (L. A.) muscle, part of the genital apparatus of rodents, atrophies after castration. Changes in end-plate structure in the L. A. muscle of castrated male rats were examined with correlated light and electron microscopic methods. Four months after castration acetylcholinesterase staining reveals, in some muscle fibres, the presence of subneural gutters composed of a succession of cuplets whereas the subneural gutters are continuous and ramified in control muscles. Six months after castration most of the end-plates are further modified. Their terminal arborization, as revealed by silver nitrate staining, is more tortuous and irregular than in controls. At the ultrastructural level, reduced sole-plate and superimposed axonal endings are seen in some end-plates three months after castration. Our findings demonstrate that the changes (reduction of muscular activity and atrophy of muscle) are accompanied by adaptations of the neuromuscular junctions. As receptors for testosterone are known to be present in these motoneurons and muscle fibres, the observed morphological changes might be under the control of testosterone acting on both muscle and motoneurons.

Acetylcholinesterase↗