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PubMed1994

Stimulation of spawning behavior in castrated rainbow trout (Oncorhynchus mykiss) by 17 alpha,20 beta-dihydroxy-4-pregnen-3-one, but not by 11-ketoandrostenedione.

The onset of spawning behavior in male salmonids can be closely correlated to circulating levels of the progestin 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (20-P). However, evidence that 20-P plays a causal role in the development and maintenance of spawning behavior in male salmonids is largely lacking. The purpose of this study was to investigate the effect of 20-P implants on the spawning behavior in castrated rainbow trout in the presence of a sexually active female. Mature rainbow trout were placed in five experimental groups: sham-operated and castrated implanted with either Silastic capsules containing 20-P, 11-ketoandrostenedione (11-KA), 11-KA + 20-P or empty capsules. Five to 6 weeks after implantation, all males were tested individually in a stream channel in the presence of a nesting ovulated female. Following behavioral observations, blood samples were taken from all tested males. Implants of 20-P and 11-KA resulted in increased plasma levels of 20-P and 11-ketotestosterone, respectively. Sham males exhibited the strongest behavioral response, both in the frequency of quiver bouts and attention toward the female. Castrated controls and 11-KA males showed no quiver response and reduced attention toward the female, while the behavioral responses shown by the 20-P and 20-P/11-KA males were intermediate. The results indicate that 20-P, but not 11-androgens, plays a significant role in the stimulation of spawning behavior in male rainbow trout.

Androstenes↗
PubMed1998

Effect of long-term castration and long-term androgen treatment on sexually dimorphic estrogen-inducible progesterone receptor mRNA levels in the ventromedial hypothalamus of whiptail lizards.

In whiptail lizards, as in laboratory rodents, females will respond to exogenous estrogen by increasing progesterone receptor (PR) or PR mRNA in the ventromedial hypothalamus (VMH) while males show an attenuated response to the same treatment. In rodents, neonatal hormone manipulations affect the adult expression of this trait; however, few investigators have examined the effects of hormone treatment in adulthood. Therefore the current study was carried out to determine whether observed sex differences in the estrogen response in adulthood may be modified by steroid hormone manipulation. We castrated male whiptail lizards for 1 week (short term) or 6 weeks (long term). We also gonadectomized female whiptails and implanted them with either a Silastic capsule containing testosterone or an empty capsule. At the end of that time all implants were removed and the animals were injected with either estradiol benzoate (EB) or steroid suspension vehicle and their brains were assayed for PR mRNA expression using in situ hybridization. The results demonstrate that in male whiptail lizards, long-term castration increases sensitivity to estradiol as measured by induction of PR mRNA in the VMH; EB-injected long-term castrated males were not different from EB-injected females. However, long-term androgenization did not attenuate the estrogen response in females. This suggests that attenuation of the estrogen response in males requires activation by testicular secretions, but that females cannot be made to show a male phenotype via testosterone administration.

Age Factors↗
PubMed2002

Parental responsiveness is feminized after neonatal castration in virgin male prairie voles, but is not masculinized by perinatal testosterone in virgin females.

We previously found a large sex difference in the parental responsiveness of adult virgin prairie voles (Microtus ochrogaster) such that most males are spontaneously parental, whereas most females are not. Because this sex difference is independent of the gonadal hormones normally circulating in adult virgin voles, the present study examined whether perinatal hormones influence the development of this sex difference. Males were treated prenatally (via their pregnant dam) with both the androgen receptor blocker flutamide (5 mg/day/dam) and the aromatase inhibitor ATD (1 mg/day/dam), or oil, for the last 2 weeks of gestation. Half of the subjects from each group were castrated on the day of birth and the other half received a sham surgery. As adults, intact males were castrated and all males received a silastic capsule filled with testosterone. Prenatal treatment with flutamide and ATD had no effect on males' behavior toward pups, but neonatal castration significantly reduced the percentage of males acting parentally. In a second experiment, females were exposed to testosterone propionate (TP; 50 microg/day/dam) or oil via their dam during the last 2 weeks of gestation. For the first neonatal week, half of the females from each group were injected with TP (1 mg/day) and the other half oil. As adults, females were ovariectomized and half from each group received a testosterone-filled capsule and the other half received an empty capsule. None of the perinatal TP treatments increased females' parental responsiveness, although females from all groups that received testosterone capsules as adults were highly parental. Therefore, although postnatal testicular hormones are necessary for high parental responsiveness in males, the behavior of females is not influenced by perinatal exposure to testosterone.

Age Factors↗
PubMed2002

Androgen implants in medial amygdala briefly maintain noncontact erection in castrated male rats.

Castration of male rats causes a rapid loss of their normal erectile response to inaccessible estrous females. Previous studies had demonstrated that these noncontact erections (NCEs), a putative sign of sexual arousal, could be restored by systemic treatment with testosterone (T) or dihydrotestosterone (DHT), but not estradiol (E). We examined whether androgen delivered to the medial amygdala (MeA) of castrated rats would maintain NCE. In Experiment 1, males received bilateral cannulae filled with T, DHT, or E directed at the MeA. Control males had the same hormone-filled cannulae implanted subcutaneously and blank cannulae in the MeA, or they received T in the anterior forebrain. During the 2 weeks after surgery, males were tested twice for NCE and copulation. About half the males with androgens in the MeA had NCEs 1 week after castration, but few responded a week later. Closer proximity of androgen implants to the posterodorsal MeA (MeApd) predicted shorter NCE latencies. No males with subcutaneous androgen had NCEs in either test, and few anterior forebrain-implanted males did. Some males receiving E in MeA or subcutaneously had NCE in each test. In copulation tests, the type of steroid treatment did not affect the incidence of ejaculation or most measures of copulation, and the proximity of cannulae to MeApd predicted only the time from ejaculation to the occurrence of NCE during the postejaculatory interval. Experiment 2 showed that NCEs displayed by males with androgen in MeA occurred in response to estrous females, not spontaneously. The results suggest that androgens, perhaps augmented by estrogen, act in the posterodorsal MeA to facilitate NCE and its associated arousal.

Amygdala↗
PubMed1991

Changes in urate metabolism after castration of patients suffering from carcinoma of the prostate.

13 patients with carcinoma of the prostate were investigated on a low purine diet before and after surgical castration, performed to slow progression of their disease. A control group of herniorrhaphy patients was similarly studied. The 2 groups were very similar pre-operatively except for urea which was higher pre-operatively in patients than controls (p0.004). Testosterone levels fell significantly in patients soon after surgery (W0.002). There was a significant fall in serum uric acid in the early post-operative phase in both patients (W0.004) and controls (W0.01) but the fall only remained significant one month after surgery in castrated patients (W0.007). Urinary uric acid levels in patients fell significantly soon after surgery (W0.04). This is a small study but results suggest that endogenous male hormones are at least partially responsible for serum uric acid levels since castration, with reduction in circulating testosterone, resulted in a fall in these levels.

Creatinine↗
PubMed1991

Effects of temperature, steroids and castration on daily torpor in the Djungarian hamster (Phodopus sungorus).

1. In Phodopus sungorus the frequency and characteristics of daily torpor were not affected by a decrease in temperature. The seasonal cycle of daily torpor is essentially under photoperiodic control. 2. Testicular regression is a necessary condition for daily torpor occurrence. Testosterone and 5 alpha-dihydrotestosterone administration totally inhibited daily torpor in hamsters which were exposed to short days. The temporal inhibition of torpor by steroids had no effect on the seasonal time measuring mechanism governing daily torpor. 3. Castration influenced certain aspects of the daily torpor display. Castrated hamsters showed a delay in terminating torpor season lending further support to the hypothesis that recrudescence of the testis plays a role in terminating the daily torpor season. Castration, when performed before or on the day of transfer to short photoperiod led to an increase in the frequency of torpor bouts and reduce SP exposure duration which is necessary for the daily torpor season beginning.

Animals↗
PubMed1988

Post-castration rebound of an androgen regulated prostatic gene.

After castration, the rat dorsolateral prostate M-40 mRNA initially decreased then rebounded to precastrated levels. The cellular site of M-40 expression and its renewed expression after castration was defined by in situ hybridization histochemistry. In situ hybridization with either a 32P-labeled or biotin-labeled M-40 cDNA probe demonstrated that M-40 mRNA levels were higher in the lateral than dorsal prostate. A second androgen regulated gene, RWB, also was highly expressed in the lateral prostate. The biotinylated cDNA probes provided microscopic resolution of the expressing cells, revealing two distinct morphologies of lateral epithelium which expressed both the M-40 and RWB mRNA. These morphologies appeared in ducts which contained either epithelial cell sheets that were highly convoluted or thinner epithelial cells with a minimal degree of convolution. The RWB mRNA decreased in both cell populations in response to androgen withdrawal. The decline and reappearance of M-40 mRNA also appeared in both epithelial cell types. These data demonstrated that after castration the M-40 mRNA initially decreased as expected for an androgen sensitive gene and then progressed to a fully inducible state. The mechanism of this progression remains to be elucidated.

Androgens↗
PubMed1987

LHRH messenger RNA in neurons in the intact and castrate male rat forebrain, studied by in situ hybridization.

The purpose of the present study was to localize luteinizing hormone-releasing hormone (LHRH) mRNA within the male rat forebrain using an in situ hybridization approach. The expression of LHRH mRNA was compared in castrate and intact males to approach questions on the chronic influences of circulating testicular steroids on the gene expression of the peptide. Frozen 10 micron sections fixed in paraformaldehyde were obtained from the forebrain region of intact and 2 week post-castrate adult male rats. LHRH mRNA was autoradiographically detected using an oligomer (59mer) complementary to the mRNA coding for amino acids -5 to 15 of the human LHRH preprohormone. Individual brain sections were incubated in prehybridization buffer for 2 h to reduce nonspecific binding. Following this, 20 microliter of hybridization buffer containing 65,000-120,000 cpm of the 59mer were applied to sections and hybridized at 37 degrees C for 3 days. The sections were then rinsed over a 48 h period, dehydrated, dipped in Kodak NTB2 liquid emulsion and exposed for 22 days. Autoradiograms were developed and counterstained with fast green and cresyl violet. As reported in the female, LHRH message-containing cells were localized in ventral septal regions, the diagonal bands of Broca, preoptic area and anterior hypothalamus. On occasion, LHRH gene expressing cells were found to appear in loose clusters. Labeled cells were never found in control sections treated with hybridization buffer lacking the 59mer. The total number of LHRH mRNA-containing cells localized in intact rats did not differ significantly from the castrate group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Renal cathepsin-B activities in rats after castration and treatment with sex hormones.

The activities of the lysosomal endopeptidase cathepsin B (cath B; CZB-Ala-Arg-Arg-MNA as substrate) and the lysosomal exopeptidase dipeptidylpeptidase II (DAP II; Lys-Ala-2NA as substrate) were fluorometrically determined in the renal homogenate of normal and experimental (castration followed by a 14-day treatment with estradiol and testosterone) rats of both sexes. In addition, methodological investigations of the renal homogenate were performed in order to differentiate cath B from other proteinases. These showed that cath-B activity was highest at around pH 6, was strongly inhibited by 4-hydroxymercuribenzoate and leupeptin, and was activated by dithiothreitol. Trypsin-like activities were not demonstrable under the used incubation conditions. The animal experiments showed that renal cath-B activities (1) were significantly higher in females than in males, (2) increased significantly in males and decreased significantly in females after castration (no significant difference between both sexes), (3) decreased in female and male castrates after treatment with testosterone and increased strongly after treatment with estradiol, and (4) showed an activity pattern similar to that of DAP II. The results are discussed in relation to the sex-dependent and sex-hormone-dependent proteinuria of rats. It is suggested that there is a correlation between protein catabolism in the kidney and proteinuria, i.e. high lysosomal proteinase activities correspond with low proteinuria.

Animals↗
PubMed1980

The parasitic castration and gigantism of Lymnaea truncatula infected with the larval stages of Fasciola hepatica.

The shells of Lymnaea truncatula infected with the larval stages of Fasciola hepatica were significantly longer than those of comparable uninfected controls. The dry mass (tissue, shell + parasite) of the same infected snails, 56 days after infection, was approximately twice that of the controls (tissue + shell). The increased mass of infected snails was not due to a disproportionate increase in shell weight relative to tissues. Infected snails maintained at 20 degrees C had virtually ceased egg production by 21 days post-infection whereas control snails continued to lay eggs steadily for the duration of the experiment. The dry mass of snail tissue plus the cumulative dry weight of eggs produced was taken as an indication of the ability of control snails to generate biomass. Similarly the tissue mass plus cumulative egg weight and parasite weight was taken as an indication of the ability of the infected snails to generate biomass. The control and infected snails were not significantly different in this respect indicating that the gigantism of infected snails could be the result of a switch in nutrient supply from reproduction to somatic tissue growth and parasite growth. Castration was brought about 17-21 days after infection as a result of the direct consumption of the ovotestis by a proportion of the redial population. In a separate experiment it was demonstrated that a population of infected snails maintained at 20 degrees C survived as long as a similar group of control snails. The findings with this host-parasite system are discussed in relation to possible mechanisms causing castration and gigantism in other digene-snail interactions, and in relation to parasitic castration in other groups. It is concluded that the observed gigantism of infected snails is more likely to have a nutritional rather than endocrine origin.

Animals↗
PubMed1993

Brain monoamines following castration of aggressive muricidal rats.

The effect of castration on the levels of brain monoamines and their metabolites has been investigated in rats which became or did not become muricidal following long-term isolation. Fourteen brain areas were explored: olfactory bulbs (OB), olfactory tubercles (OT), septum (Se), striatum (Sr), amygdala (A), thalamus (Th), hypothalamus (Hy), hippocampus (Hi), superior colliculus (SC), inferior colliculus (IC), raphe (Ra), pons-medulla (PM), frontal cortex (FC), temporal cortex (TC) and parietal cortex (PC). Except in the raphe of non muricidal rats and in the striatum of muricidal animals, all other areas examined demonstrate some changes of monoamines neurotransmitter or their metabolites after castration. The strongest changes, always increases, were found in the thalamus. In several brain areas, the changes occurring after castration, differ quantitatively and qualitatively in muricidal and non-muricidal rats.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Comparative effects of preoptic area infusions of opioid peptides, lesions and castration on sexual behaviour in male rats: studies of instrumental behaviour, conditioned place preference and partner preference.

The effects on the sexual behaviour of male rats of excitotoxic amino acid-induced lesions of the medial preoptic area-anterior hypothalamic area (mPOA/AHA), infusions of beta-endorphin, alpha-melanocyte stimulating hormone and naloxone into the mPOA/AHA, systemic naloxone and castration were compared using different behavioural paradigms. These included measures of unconditioned copulatory behaviour, instrumental responses for an oestrous female presented under a second-order schedule of reinforcement, conditioned place preference and partner preference. The results demonstrate that manipulations of the mPOA/AHA markedly affect consummatory aspects of sexual behaviour (mounting, intromitting and ejaculating) but tend not to affect appetitive or reward-related aspects of sexual behaviour, although intra-mPOA/AHA alpha MSH did result in a small increase in instrumental responses, while beta-endorphin infused into the mPOA/AHA also abolished preference for an oestrous over an anoestrous female. Systemic naloxone, on the other hand, reduced instrumental behaviour and a place preference conditioned by prior sexual interaction, while the same compound infused into the mPOA/AHA markedly facilitated copulatory responses but did not affect other measures of appetitive sexual responses. Castration caused an extremely rapid attenuation of conditioned place preference which was apparent before the males had experienced reductions in their copulatory performance. This treatment only slowly reduced partner preference. The results indicate that the use of several behavioural procedures can reveal discrete actions of neuroendocrine treatments on separable psychological processes which underly the integrated pattern of masculine sexual behaviour. In particular, they suggest that the mPOA/AHA is especially concerned with the copulatory responses of mounting and intromitting, but is much less important for a variety of appetitive sexual acts as well as sexual reward, as measured in the place preference procedure. The marked effects of castration on conditioned place preference taken together with the lack of effect of lesions of the mPOA/AHA on this measure indicate that testosterone affects sexual reward-related processes by an action at a site other than the mPOA/AHA. The implications of these findings are discussed.

Animals↗
PubMed1996

Steroid 5 alpha-reductase type 1 immunolocalized in the anterior pituitary of intact and castrated male rats.

The localization of 5 alpha-reductase was immunohistochemically studied in the anterior pituitary of male rats, using a polyclonal antibody against 5 alpha-reductase rat type 1. The immunoreactive cells were concentrated in the central region and on the border of the intermediate lobe in the anterior pituitary, but not in the intermediate or posterior lobe. The immunoreaction was located mostly in the cytoplasm and occasionally in the cell nuclei. The immunoreactive cells showed alterations in size and number and in the intensity of the immunoreaction after gonadectomy. One week after castration, the cells became larger and the immunoreactivity increased. Two weeks after castration, the number of immunoreactive cells increased. Double immunostaining using anti-luteinizing hormone beta-subunit or anti-follicle stimulating hormone beta-subunit antibody revealed that most of the cells containing 5 alpha-reductase were gonadotrophs. Electron microscopically, the immunoreactive cells showed lamelliform rough endoplasmic reticulum and a depletion of secretory granules 1 week after castration. One week later, the rough endoplasmic reticulum was developed and dilated and the number of secretory granules increased. These results suggest that 5 alpha-reductase is located in the gonadotrophs of rat anterior pituitary and that it is involved in the feedback regulation of gonadotropin secretion by androgens.

Amino Acid Sequence↗
PubMed1997

Modulation of preoptic regulatory factor-2 (porf-2) mRNAs by castration and hypophysectomy.

Neuropeptides are central to the regulation of mammalian gender-dependent development and reproduction. Preoptic regulatory factor-2 is a neuropeptide gene that is known to be expressed in rat brain and testis. In the brain, expression is gender-dependent and age-dependent. Tissue-specific transcripts are found in the preoptic area (POA) of the hypothalamus and in the testis. In order to investigate the effects of reproductive hormone status on expression of porf-2 in the male rat, porf-2 transcripts were studied by Northern blot analysis in intact, hypophysectomized, and castrated rat POA, medial basal hypothalamus (MBH), cerebral cortex (CC), testis, and liver. Castration of hypophysectomy increased levels of the brain-specific 0.84 kb 5' porf-2 transcript in the POA, but did not affect levels of this transcript in the CC. There was a small decrease in the MBH following castration. Hypophysectomy also resulted in a fourfold increase in the 5' 1.1 kb testis-specific transcript. The affected transcripts are localized to the cytoplasm. A nontissue specific 3' transcript was also detected. Interestingly, this 0.6 kb transcript became non-detectable in all tissues examined following hypophysectomy. Porf-2 mRNA was also detected in human hypothalamus, testis, adrenal, placenta, and prostate with unique transcripts in each tissue examined . It has been shown elsewhere that porf-2 is a unique single copy gene in the rat genome. These data demonstrate that expression of the porf-2 gene is differentially regulated at the pretranslational level by intrinsic tissue-specific, as well as extrinsic pituitary and gonadal factors. The selected responses to reproductive hormonal status suggest that porf-2 may play a role in hypothalamic pituitary-gonadal interactions.

Animals↗
PubMed2000

Gonadal steroids and bone metabolism in young castrated male rats.

At 45 days of age, 40 male Wistar rats were castrated, then randomly divided into four groups, S.C. injected for 60 days after surgery either with 17beta-estradiol (E) 10 microg/kg BW/48 hours, progesterone (P) 140 microg/kg BW/48 hours, dihydrotestosterone (D) 2 microg/kg BW/48 hours, E + P + D same doses, or solvent alone (CX). Ten other rats were sham-operated (SH) and used as controls. Animals were put in balance to determine Ca and phosphorus (Pi) intestinal apparent absorption (IA Ca, IA Pi) and urinary pyridinium crosslinks excretion. Plasma was collected for measurement of intact-parathyroid hormone (PTH), calcitonin (CT), insulin-like growth factor I (IGF-I), 1,25 dihydroxyvitamin D (1,25(OH)(2)D), Ca, and Pi. Orchidectomy induced marked seminal vesicles atrophy and increased plasma CT, PTH, and Ca concentrations. IA Ca was significantly higher in P rats, however, neither castration nor any other treatment had significant effects. Orchidectomy decreased femoral length, dry weight, and Ca content, whereas E or D given alone or together with P improved endochondral growth and enhanced femoral Ca content. Again, bone mineral density was lowered by orchidectomy and reestablished by both E and EPD, even above SH values, this effect being more important at the metaphyseal levels. Urinary pyridinium cross-links excretion and plasma osteocalcin concentrations were higher in the CX animals than in the controls. Although E and D given alone did reduce both biochemical turnover markers, they showed additive effect when given together (EPD). In conclusion, in the young castrated male rat, E was more efficient than D for preventing bone loss, the most important effect being induced by a combination of E+P+D.

Amino Acids↗
PubMed1999

Ultrastructural and biochemical observations on the early changes in apoptotic epithelial cells of the rat prostate induced by castration.

The present study describes the sequential ultrastructural changes in the apoptotic cells of the rat ventral and dorsal prostates during the early period of 1-3 days postcastration. The major morphological changes include: (1) condensation of heterochromatin along the nuclear envelope and fragmentation into crescent-shaped micronuclei; (2) formation of membrane-bound cytoplasmic spherical bodies, which contain various organelles and micronuclei, within the apoptotic cells; (3) formation of non-membrane-bound autolytic vacuoles by autolysis of cytoplasm; (4) focal rupture of outer mitochondrial membrane; and (5) phagocytosis of the fragmented cytoplasmic spherical bodies and apoptotic cells by macrophages. The occurrence of both cytoplasmic apoptotic bodies and autolytic vacuoles in apoptotic cells suggests that the cytoplasm of the apoptotic cells could be destroyed by different means. The responsiveness of different prostatic lobes to androgen withdrawal and the time course of the transitory apoptotic activity in different lobes were analyzed by counting the indices of the TUNEL-labeled apoptotic cells against the postcastration periods. The results showed that the ventral lobe responded more rapidly to castration than the lateral and dorsal lobes. The dorsal lobe was the slowest in response to castration among the three lobes. Analysis of protease activities by zymography has identified two Ca(2+)-independent proteases of apparent MW 20 and 24 kDa (expressed in both ventral and dorsolateral lobes), and one Ca(2+)-dependent protease of MW 66.5 kDa (expressed only in the dorsolateral lobe) which became activated at day 3 postcastration. Their expression patterns were different from that of CPP-3 in the castrated prostates, suggesting that the activated proteases were enzymes other than CPP-3. The association of their highest activities with the maximum apoptotic activity at day 3 postcastration and also their loss of activity at day 15 suggest that these protease activities might be related to apoptosis or glandular involution.

Animals↗
PubMed1989

Effects of castration, steroid replacement, and sexual experience on mesolimbic dopamine and sexual behaviors in the male rat.

The concentrations of dopamine (DA) and a DA metabolite in a terminal field of the mesolimbic DA system, the nucleus accumbens, decreased after castration, an effect that was prevented by treatment with testosterone (T) or estradiol. After castration, DA concentrations were increased in the medial preoptic area, and were unchanged in the caudate-putamen, substantia nigra, and ventral tegmental area. Changes in DA and DA metabolite concentrations in the nucleus accumbens coincided with changes in measures of sexual arousal. Sexual experience did not affect DA concentrations, but did increase DA metabolism in the nucleus accumbens, and also increased the frequency of female-directed behavior in castrated males. These results suggest that T, or its aromatized metabolite, influences the mesolimbic DA system, and that this system is involved in mediating sexual arousability.

Animals↗
PubMed1989

[3H]imipramine binding in discrete brain areas is affected by castration in male rats.

In adult male rats, castration induces a progressive decrease in the number of [3H]imipramine binding sites in the cerebral cortex and hypothalamus, and a progressive increase in the hippocampus. Testosterone completely prevents this effect of castration, but has no effect on the characteristics of brain imipramine binding sites in intact, non-castrated animals. These data suggest that threshold levels of testosterone are necessary for the maintenance of a normal number of imipramine binding sites in the rat brain, but that these binding sites are not modified by excess testosterone.

Animals↗