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PubMed1993

Effect of neonatal diethylstilbestrol exposure on luteinizing hormone secretion following ketamine anesthesia and gonadotropin-releasing hormone in castrated postpubertal rats.

Neonatal diethylstilbestrol (DES) exposure diminishes pituitary responsiveness to GnRH in castrated postpubertal rats 4 h after placement of intra-atrial cannulae under ketamine anesthesia. Ketamine anesthesia has been reported to blunt the preovulatory LH surge in female rats and to decrease baseline LH levels in males immediately following administration, although its effect lasted less than 2 h. It is not known what impact ketamine has on baseline LH levels or on GnRH-stimulated LH release in estrogen-exposed castrated rats. This study was designed to determine 1) whether the changes in GnRH-induced LH secretion in DES-exposed castrated rats are partially attributable to a direct effect of ketamine; 2) the gender-specific effects of ketamine on LH secretion; and 3) the DES-dependent effects of ketamine on LH secretion. In this experiment we ascertained the effect of ketamine anesthesia for right heart cannulation on LH levels in male and female 42-day-old castrated rats that were exposed to either corn oil or DES (0.1 microgram/day) on Days 1 through 10 of life. LH secretion in DES-exposed animals increased, in contrast to that in control animals, immediately (< 10 min) after anesthesia and cannulation. Mean LH levels in DES-exposed females were lower than in controls before GnRH administration and were blunted following GnRH. While ketamine and catheterization were associated with decreased LH titer in males, the extent of that decrease was not dependent on exposure to DES. Both sexes and exposure groups achieved baseline catheter LH values by 4 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1992

Oestrogen-induced suppression of collagen arthritis; 17 beta-oestradiol is therapeutically active in normal and castrated F1 hybrid mice of both sexes.

The F1 hybrid mouse strain, from B10Q and DBA/1 parentals (the QD strain), is highly susceptible to induction of type II collagen-induced arthritis, an experimental model for rheumatoid arthritis. Males are more susceptible than females. Oophorectomy enhances susceptibility to arthritis and treatment with physiological doses of 17 beta-oestradiol (E2) suppresses disease. E2 treatment lowers the incidence of arthritis also in non-castrated and castrated males, showing that the anti-arthritic effect by oestrogen is not dependent on either sex hormone imprinting effects or interference with male sex hormones. Testosterone treatment of normal females, but not of castrated females, exaggerated development of the disease. In the testosterone-treated normal females, the oestrogen effect on vaginal smear was abolished and ovarian weight decreased, suggesting that the testosterone-mediated enhancing effect is caused by inhibition of ovarian oestrogen production. The crucial importance of oestrogens for the development of arthritis is focused on the effectiveness of treatment with gestation-related doses of E2 of normal, non-castrated females.

Animals↗
PubMed1989

Gamma-glutamyl transpeptidase in rat epididymis: effects of castration, hemicastration and efferent duct ligation.

Gamma-Glutamyl transpeptidase (gamma-GT) was studied histochemically and biochemically in the rat epididymis after castration with or without testosterone treatment, or after hemicastration and ligation of the efferent ducts. There was a strong reaction to gamma-GT in the apical part of the epithelium in the caput epididymis, while in the corpus and cauda the reaction was confined mainly to the luminal contents. Castration caused a marked decline in epithelial gamma-GT activity within 10 days. Subsequent testosterone treatment (1 mg/day for 10 days) restored gamma-GT activity in the apical surface and lumen. After hemicastration of adult rats, and after hemicastration or ligation of the efferent ducts in immature 28-day-old rats, a small but significant (P less than 0.001) decrease was observed in gamma-GT activity in the epididymal caput compared to controls. The quantities of six other enzymes (beta-N-acetylglucosaminidase, beta-galactosidase, angiotensin-converting enzyme, alanyl amino-peptidase, dipeptidyl peptidase IV, acid phosphatase) also displayed significant changes after castration and restoration of activities by testosterone treatment. However, their distribution in the caput and cauda epididymis was more even than that of gamma-GT, and the changes after castration were less drastic. It is concluded that gamma-GT is a highly sensitive androgen-dependent secretory marker in the caput epididymis and may have an important function in sperm maturation.

Animals↗
PubMed2006

Evaluation of a Burdizzo castrator for neutering of dogs.

A Burdizzo castrator was evaluated for the neutering of dogs. Histological and morphological changes of spermatic cells and peripheral serum testosterone after challenge with a GnRH-analogue (gonadorelin) were assessed. There was a control group (G1), a surgically castrated group (G2) and a Burdizzo group (G3) divided in two, G3a receiving two crunches in each spermatic cord and G3b receiving one crunch in each spermatic cord. Sixteen days after application of the Burdizzo blood samples were taken from the dogs at 30 min interval during 2 h; after the second sample the dogs were treated with 1 mug/kg body weight of gonadorelin i.v. The same protocol of gonadorelin challenge was performed in G1 and G2 dogs. The G2 dogs were surgically castrated after the second blood sample, before the gonadorelin treatment, and the G1 dogs after the last blood sample. The excised gonads were examined histologically, and sperm smears were prepared from the caudae epididymidis. The testes and plexus pampiniformis of the G1 and G2 dogs had a normal histological appearance, and they had morphologically normal epididymal sperm cells. In all G3 dogs, there was an acute fibrosis with an inflammatory reaction in the plexus pampiniformis. The testes from the G3a dogs showed diffuse areas of infarction and degeneration of the parenchyma. Similar but less diffuse lesions were seen in group 3b dogs. The deferent ducts from all G3 dogs showed vasitis and/or sperm granulomas. Azoospermia or sperm malformations were observed in the epididymal smears from the G3 dogs. Testosterone concentration in the G1 dogs increased after gonadorelin application (p < 0.0001). The G2 dogs had basal testosterone levels after castration (p < 0.001) and did not respond to gonadorelin. Groups 3a and b showed a slight but non-significant increase in testosterone concentration after gonadorelin challenge, supposedly due to the reduction of testicular blood flow and loss of testicular interstitial tissue.

Animals↗
PubMed2007

Pinhole castration: a novel minimally invasive technique for in situ spermatic cord ligation.

OBJECTIVE: To describe a minimally invasive technique for castration of bull calves by in situ ligation of the spermatic cord. STUDY DESIGN: Experimental study. ANIMALS: Male calves (n=6) aged, 48-56 days. METHODS: Calves were blocked by weight and then separated into 3 groups: (1) bilateral spermatic cord ligation; (2) unilateral-1 spermatic cord ligated; and (3) control-neither spermatic cord ligated. After local anesthesia, in situ spermatic cord ligation was achieved by restraining the cord laterally within the scrotal sac and passing suture through a hypodermic needle inserted caudal to cranial at the neck of the scrotum and adjacent the medial margin of the restrained spermatic cord. The needle was removed leaving the suture in place and the spermatic cord repositioned medially, then the needle was reinserted through the original holes and the suture passed back through the needle, which was withdrawn. The suture ends were tied ligating the spermatic cord, leaving the knot subcutaneously. Calves were monitored and testes removed after 30 days for gross and histologic examination. RESULTS: Castration was accomplished without postoperative complications. Spermatic cord ligation resulted in testis atrophy, and histologically, complete ischemic necrosis. CONCLUSIONS: This novel minimally invasive technique is a simple, alternative method for castration of bull calves. CLINICAL RELEVANCE: This method of castration is simply performed, without obvious skin wounds, and no postoperative care needed. The technique should be readily adaptable to other species.

Animals↗
PubMed1988

Effects of postpuberal castration on dopamine receptor sensitivity in the male rat brain.

In order to study the effects of castration of brain dopamine (DA) receptor sensitivity, the effects of apomorphine on locomotor activity and striatal DA synthesis, as assessed by the dihydroxyphenylalanine (DOPA) accumulation after NSD-1015 treatment, were examined in normal and castrated male Sprague-Dawley rats pretreated with reserpine (5 mg/kg-18 hrs). There was an enhanced locomotor response to apomorphine (0.05-0.1 mg/kg) in castrated animals, as compared to sham operated controls. Furthermore, the increase in DOPA accumulation produced by the reserpine treatment was antagonized to a greater extent by apomorphine in the castrated animals. These results indicate an enhanced DA receptor sensitivity at both pre- and post-synaptic sites.

Animals↗
PubMed1975

Parasite reproductive strategy and evolution of castration of hosts by parasites.

A modification of the Euler equation is used to describe a simple parasite life history in which survival decreases with age at a rate determined by mortality of the parasitized host. The advantages of castration of hosts by parasites are discussed using the modified equation in which castration is equivalent to reducing parasite virulence in the host to near zero or zero. It is suggested that castrating parasites can infest a wider range of hosts with higher mortality rates and that within parasite groups having castrating and noncastrating species, the former should infest hosts with higher mortality rates and relatively larger gonads.

Ecology↗
PubMed1987

A comparison of the effects of castration and 6-methylene progesterone, a 5 alpha-reductase inhibitor, on the rat ventral prostate.

6-Methylene progesterone (6MP) is an irreversible in vitro kcat inhibitor of rat prostate 5 alpha-reductase, the enzyme which converts testosterone (T) to dihydrotestosterone (DHT). Treatment of adult rats with 6MP or diethylstilbestrol (DES) decreased the weight of the ventral prostate (VP) by 45%, while castration reduced it by 86%. Histologically, the 6MP-treated VP were indistinguishable from those of controls, while the VP from DES-treated rats showed fibrous stromal hypertrophy as in castrated rats. The prostatic hydroxyproline content, an index of collagen levels, was enhanced by castration or DES, but was not significantly increased by 6MP. Within 2 days of 6MP treatment, the 5 alpha-reductase activity was reduced by 46% and ornithine decarboxylase (ODC) activity was lowered by 27%. During this time the prostatic acid phosphatase activity increased 42% and remained elevated with continued exposure to 6MP up to 13 days. The castration-induced involution of the VP was accompanied by a reduction in serum T and an increase in serum luteinizing hormone (LH). 6MP had no effect on T and LH serum levels but reduced the DHT content within the VP by 64%. Our results indicate that the structure and secretory acid phosphatase activity of the VP are less sensitive to changes in the ratio of T:DHT than is cell proliferation. Thus, the relative amounts of DHT and T within the VP may prove to be more significant than the absolute amount of either androgen in controlling prostate growth or its attendant neoplasms.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1987

Effects of photoperiod on hibernation in castrated Turkish hamsters.

Hibernation and circulating reproductive hormones [luteinizing hormone, follicle-stimulating hormone, and prolactin (LH, FSH, and PRL)] were studied for greater than 40 wk in castrated male Turkish hamsters (Mesocricetus brandti) housed in either a long-day cold or short-day cold environment. A significantly greater percentage of short-day animals hibernated than did long-day animals, indicating that short-day exposure can predispose Turkish hamsters to enter hibernation and that this photoperiodic effect cannot be explained entirely by the inhibitory influence of short days on testicular endocrine activity. Long-day castrates showed no significant changes in LH or FSH levels during the experiment. In the short-day castrates serum LH, FSH, and PRL levels were reduced after 4-9 wk and increased again after 18-23 wk of short-day exposure. The hibernation season ended after 30-34 wk on short days, several weeks later than in testis-intact males studied previously. These results indicate that gonadal factors are not required for the termination of hibernation but may influence its timing. The resumption of FSH secretion occurred no later during short-day exposure in castrated hibernators than in the preceding study of testis-intact, short-day males hibernating in the cold or those held at room temperature. Thus the endogenous timing mechanism regulating the reactivation of the hypothalamopituitary axis toward the end of the winter season is apparently gonad independent and is little affected by the low body temperatures experienced during hibernation.

Animals↗
PubMed2003

Functional development of the rat urinary bladder after pre- or postpubertal castration.

Experiments were done to evaluate the role of sex hormones in the functional development of the rat urinary bladder. Rats were orchiectomized or ovariectomized at 30 (prepubertal) or 70 (postpubertal) days of age and bladders were removed 1 month later. An additional group of immature male and female rats was used in which the bladders were removed at 30 days of age. There were only minor differences in contractile responses of bladder strips from any group to electrical field stimulation, ATP, carbachol, or KCl compared to age-matched controls. There were no differences in responses of bladder strips from immature females or males to the adrenergic agonists, isoproterenol, norepinephrine, or methoxamine. Bladders from the pre- and postpubertally castrated rats and their controls relaxed fully in response to isoproterenol, but strips from prepubertally castrated rats relaxed significantly less in response to norepinephrine than those from other groups. Approximately one half of the bladder strips from prepubertally castrated rats failed to relax by at least 50% in response to norepinephrine; these same strips responded to methoxamine with exaggerated contractions. Our data indicate that the normal development of rat bladder alpha-adrenergic responsiveness is adversely altered by prepubertal castration. We postulate that this may result from an alteration in the relative expression of alpha(1)-adrenergic receptor subtypes.

Adenosine Triphosphate↗
PubMed1988

Development of the subfornical organ and area postrema of the male albino mouse. Karyometric effect of neonatal and prepuberal castration.

We have studied the karyometric development of the nuclei of the ependymal cells and neurons of the subfornical organ and the area postrema in the male albino mouse from the 5th to the 190th postnatal day. We have found similar patterns of development in both although the area postrema showed more significant postnatal oscillations than those of the subfornical organ, suggesting a more intimate chronological relationship to gonadal development. We have furthermore analyzed the development in two experimental groups: in the one animals were castrated at birth, in the other, castration was made on the 20th postnatal day. We have found that neonatal castration produced a significant decrease of nuclear sizes; this was more evident in the subfornical organ than in the area postrema in earlier stages of development while the response was similar in both at peripuberal ages. The response to prepuberal castration was similar in both organs.

Aging↗
PubMed1986

Effects of castration on androstenedione, testosterone and dihydrotestosterone plasma levels in adult male rats.

In the present study we investigated the effects of castration on androstenedione (A), testosterone (T) and dihydrotestosterone (DHT) plasma levels in adult male rats 5 and 47 days after castration. In another group of 60-day-old castrated rats, the three steroids have been evaluated during testosterone propionate administration. Our data show that 5 days after orchiectomy all three steroids were significantly decreased (p less than 0.001) with respect to control values. 47 days after orchiectomy, T and DHT were also significantly decreased with respect to the control group. In both groups of orchiectomized rats the A/T ratio increased significantly with respect to controls. On the contrary, the T/DHT ratio sharply decreased. This suggests that DHT, in orchiectomized rats, could derive from precursors other than T. A negative correlation between A and the T/DHT ratio was observed 47 days after castration in adult animals and emphasized upon testosterone propionate administration. In the latter group, T was significantly lower while A is significantly augmented with respect to control values. Finally, the above-mentioned negative correlation indicates a possible prevalent role of A in contributing to the circulating levels of DHT in adult orchiectomized rats.

Androstenedione↗
PubMed1989

Urinary output modulation of alanine aminopeptidase, gamma-glutamyl transpeptidase and N-acetyl-beta-D-glucosaminidase by castration and testosterone in male normal rat.

The urinary excretion of alanine aminopeptidase (AAP), gamma-glutamyl transpeptidase (gamma-GT) and of N-acetyl-beta-D-glucosaminidase (NAG) was studies in normal and castrated rats receiving either testosterone for 5 post-operative weeks or no hormone. In castrated rats the urinary output of AAP and gamma-GT was significantly lower than in sham control or in castrated rats receiving testosterone. In addition, an excess of exogenously given testosterone had no effect on enzymuria of normal rats. The urinary excretion of NAG was influenced neither by castration nor by testosterone. These results suggest that endogenous testosterone is responsible for a permanent positive control on the urinary excretion of AAP and gamma-GT.

Acetylglucosaminidase↗
PubMed1999

Natural androgens inhibit male atherosclerosis: a study in castrated, cholesterol-fed rabbits.

The effect of natural androgens on serum lipids and atherosclerosis is controversial. We therefore studied this important issue prospectively in an animal model of atherosclerosis. Eighty male rabbits were randomized to bilateral castration, and 20 animals were sham operated. The castrated rabbits were randomized to 500 mg oral dehydroepiandrosterone (DHEA) daily, 80 mg oral testosterone undecanoate (TU) daily, or 25-mg intramuscular injection of testosterone enanthate (TE) twice weekly, whereas the fourth castrated group (placebo) and the sham-operated rabbits did not receive any hormones. All animals were fed a cholesterol-rich diet during the 30-week treatment period. Average serum lipids and atherogenic lipoproteins were higher in the placebo group than in the other groups (ANOVA, P<0.0001). Aortic atherosclerosis, as evaluated by the cholesterol content (nmol/mg protein), was also highest in the placebo group (308+/-39) and lowest in the TE group (61+/-12), but was intermediate in the DHEA (155+/-30), TU (191+/-43), and sham operation (162+/-29) groups (ANOVA, P<0.0001). ANCOVA indicated that the androgen effect on aortic atherosclerosis was only in part explained by the changes in lipoproteins. Aortic estrogen receptor contents were significantly lower in the androgen-treated groups than in the control groups, whereas there was no difference in aortic androgen receptor contents between groups. Natural androgens inhibit aortic atherosclerosis in castrated male rabbits only partly through a lipid-mediated effect.

Adrenal Glands↗
PubMed1998

Castration prevents calcium channel blocker-induced gingival hyperplasia in beagle dogs.

1. The purpose of this study was to investigate testosterone's role on the calcium channel antagonist oxodipine-inducing gingival hyperplasia in a dog model. 2. Two experiments were conducted using castrated and intact male dogs. Oxodipine was administered orally for 90 days, at a dose of 24 mg/kg/day. In the first experiment, the occurrence of gingival hyperplasia was evaluated. In the second, the gingival index (GI) and gingival hyperplasia index (GHI) were recorded and correlated with serum levels of testosterone. 3. A significant positive correlation between GI, GHI and plasma testosterone was noted. Castrated dogs were injected with testosterone, 4 months after the start of oxodipine treatment, while in the non-castrated dogs, administration of oxodipine was stopped. Castration correlated with lack of GH, while testosterone injection to the same dogs was associated with an increase of GI and GHI. 4. Since it is known that testosterone receptors are present in the gingiva, it is proposed that oxodipine-induced gingival hyperplasia could be mediated by the calcium channel blocker on plasma testosterone levels.

Animals↗
PubMed1999

Effect of castration on rabbits housed in littermate pairs.

Conventional solitary caging for research rabbits precludes many postural and social behaviors. Several studies that have investigated enrichment strategies for rabbit does have found intact males usually too aggressive for paired or group housing. This study investigated the possibilities that male siblings will remain compatible if never separated from birth and that castration will improve compatibility among young sibling male rabbits. As a side benefit of pair housing for all rabbits, the larger cages (modified dog cages) allowed rest and other postures not possible in conventional single cages. In addition, there was no evidence of the stereotypies observed among individually housed rabbits. Castrated, post-weanling, male, Flemish Giant x Giant Chinchilla rabbit littermates demonstrated a significantly higher level of living together compatibly than did the intact controls. All rabbits chose to rest in close proximity or contact, although this preference was stronger in castrated males. During puberty, intact males displayed more serious aggression. We conclude that young adult littermate rabbits can live compatibly as pairs and that castration improves compatibility among males. Paired rabbits exhibit many postures and behaviors that are not possible in the small, solitary cages currently listed as minimum recommendations.

Journal Article↗
PubMed1986

Effects of castration and testosterone administration on serum lipoproteins and their apoproteins in male spontaneously hypertensive rat.

Serum triglyceride and very low density lipoprotein (VLDL) concentrations were higher in male spontaneously hypertensive rat than in male control Wistar Kyoto rat, whereas serum cholesterol, phospholipids, and high density lipoprotein (HDL) concentrations were lower. Castration of hypertensive rats induced an increase in serum cholesterol, phospholipids, and HDL, and a decrease in serum triglyceride and VLDL. The cholesterol content of HDL increased, whereas the triglycerides decreased after gonadectomy of hypertensive rats. These changes in serum lipids and lipoproteins could be reversed by the administration of testosterone. Apolipoprotein E contents in VLDL and HDL of hypertensive rats were low when compared with control rats but rose after castration and could be reduced by testosterone administration. Hypertensive rats accumulated triglycerides and cholesterol in the liver, which resulted in an increase of liver weight. Castration reduced the hepatic lipids as well as liver weight. The effects of castration and testosterone treatment on lipids and lipoproteins were more prominent in spontaneously hypertensive rats than in control rats. These results suggest that testosterone reduces VLDL catabolism which is related to changes of apolipoprotein composition, and that hypertensive rats are more sensitive to testosterone than control rats.

Animals↗
PubMed1991

Androgen receptor expression in the developing rat prostate is not altered by castration, flutamide, or suppression of the adrenal axis.

Mesenchymal epithelial interactions are believed to be important to the growth and development of the neonatal prostate. Prior studies in the rat ventral prostate, using autoradiography and tritiated dihydrotestosterone, indicate that androgen receptors are present in the prostatic stroma on day 3 and are detected in the epithelium by the tenth postnatal day. These findings suggested that androgen stimulation of the prostatic mesenchyme is a crucial step in the growth and development of the prostate. We have examined this developmental program directly using polyclonal antibodies that recognize specific epitopes of the androgen receptor to examine the pattern of androgen receptor expression in intact and neonatally castrate animals. In keeping with previous studies, androgen receptors are present in the prostate stroma at birth and subsequently appear in the prostatic epithelium by the 10th postnatal day. Development of androgen receptor expression in the epithelium was not changed when the animals were castrated at birth, castrated and blocked by flutamide, or castrated and given hydrocortisone to suppress the production of adrenal androgens. These findings suggest that the appearance of androgen receptors in the prostatic epithelium is programmed by androgens before birth or that factors other than testicular or adrenal androgens control the development of epithelial androgen receptors.

Adrenal Glands↗