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PubMed1982

Effects of zinc deficiency and castration on fatty acid composition and desaturation in rats.

The effects of zinc deficiency and testosterone on fatty acid composition of plasma lipids and microsomes of liver, intestine and testes were studied. The activities of fatty acid desaturase (delta 6 and delta 5) in rat liver and testes were also measured. A significant decrease in the level of arachidonic acid was observed in plasma of normal rats fed the zinc-deficient diet. Castration significantly decreased arachidonic acid but increased 20:3 fatty acid, which is negligible in normal rats. Testosterone and zinc administration restored arachidonic acid to normal values. Zinc deficiency does not significantly change the fatty acid profile in liver, but castration decreased both arachidonic and 22:6 fatty acid. Intestinal mucosal microsomes showed that the predominant fatty acid in this tissue, palmitic acid, is independent of zinc status, whereas polyunsaturated fatty acids 18:2 and 20:4 were decreased by zinc-deficient diet or castration. Zinc deficiency sharply decreased 22:5 fatty acid and to some extent, other polyunsaturated fatty acids in testis microsomes. These changes in fatty acids are in agreement with increased delta 9 desaturation and decreased delta 5 desaturase activity. In testes, both delta 6 and delta 5 desaturase activities are decreased in zinc deficiency. It appears that zinc influences the conversion of linoleic to arachidonic acid, whereas testosterone influences delta 6 desaturase activity. The data suggest that zinc deficiency may be one of the important factors in the causation of polyunsaturated fatty acid deficiency, which, in turn, may induce serum hypertriglyceridemia.

Animals↗
PubMed1982

The influence of androgens, anti-androgens, and castration on cell proliferation in the jejunal and colonic crypt epithelia, and in dimethylhydrazine-induced adenocarcinoma of rat colon.

Androgenic hormones have previously been shown to promote cell proliferation in the small intestine of rat and androgen receptors have been demonstrated in carcinomata of the large intestine of rat. In this study the influence of testosterone and of castration on epithelial cell proliferation in the small intestine, the large intestine and in dimethylhydrazine-induced colonic tumours is compared. Cell proliferation in the small intestine and in colonic tumours was accelerated by testosterone treatment, and cell proliferation in colonic tumours, but not in the small intestine, was retarded following castration. Cell proliferation in colonic tumours was also inhibited by the anti-androgenic drug, Flutamide. Testosterone and castration each failed to influence cell proliferation in the colonic crypt epithelium of both normal and carcinogen-treated animals.

Adenocarcinoma↗
PubMed1984

Long-term variations in plasma gonadotropins in early castrated male rabbits.

LH and FSH levels were determined by RIA in plasma samples collected every 10 days from 30 to 90 days and at 4, 5 and 6 months in control male rabbits and in rabbits castrated at 30 days of age. At all stages studied gonadotropin levels were significantly increased in castrates. Mean LH levels were not influenced by age in controls or in castrates. Mean FSH levels were age dependent and increased during sexual maturation in both groups. The results showed that the secretion of FSH, but not that of LH, may be stimulated during prepubertal and pubertal stages in males where steroidal inhibition is absent.

Age Factors↗
PubMed2006

Oestrogen modulation of the effect of 8-OH-DPAT on prepulse inhibition: effects of aromatase deficiency and castration in mice.

OBJECTIVE: The aim of this study was to investigate the interaction of sex steroid hormones, particularly oestrogen, in the regulation of prepulse inhibition (PPI) by serotonin-1A (5-HT1A) receptors. MATERIALS AND METHODS: We studied aromatase knockout (ArKO) mice, which are unable to produce oestrogen but have high levels of testosterone, and the effects of castration. RESULTS AND DISCUSSION: Treatment of male ArKO mice with the 5-HT1A receptor agonist, 8-hydroxy-dipropyl-aminotetralin (8-OH-DPAT), caused an increase in PPI that was significantly greater than in male wild-type controls. Castration of male mice caused a significant enhancement of the effect of 8-OH-DPAT in control mice; however, there was no change in the effect of this drug in ArKO mice. There was no significant effect of 8-OH-DPAT on PPI in either female ArKO or wild-type controls. In all experiments, the effects of 8-OH-DPAT on startle were not different between the groups. [3H]8-OH-DPAT autoradiography showed no differences in 5-HT1A receptor binding densities in areas of the forebrain, hippocampus or raphe region that could explain the PPI results. These data show that the absence of oestrogen in male ArKO mice leads to a greater effect of 5-HT1A receptor stimulation on PPI. This effect can be mimicked in male control mice by castration. The differential involvement of oestrogen and testosterone in these animal models is discussed.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2001

Sexual differences and effects of castration on secretory mode and intracellular calcium ion dynamics of golden hamster Harderian gland.

The aim of the present work was to study the sexual differences in secretory mechanisms and intracellular calcium ion dynamics in the Harderian gland of the golden hamster. In both sexes the Harderian gland consisted of small and large lobes. In the intact control male glands the secretory portions of both lobes showed wide lumina that contained secretory material and cytoplasmic fragments, suggestive of the occurrence of exocytosis and apocrine secretion. After perfusion with HEPES-buffered Ringer's solution containing 10 microM carbamylcholine (CCh), the glandular cells showed features of enhanced secretion and a rise in intracellular calcium concentration ([Ca2+]i). In the intact control female gland the lumina of most secretory portions in the large lobe contained porphyrin accretions, and exocytosis was the sole secretory mechanism. Stimulation of the large lobe with 10 microM CCh did not raise [Ca2+]i or cause enhanced secretion. The small lobe in females resembled the male gland in secretory functions, and CCh administration caused enhanced secretion and a rise in [Ca2+]i. Castration in males abolished apocrine secretion; exocytosis became the sole secretory mechanism, and stimulation of the glandular cells with CCh did not cause enhanced secretion or induce a rise in [Ca2+]i. To the contrary, in females, castration restored apocrine secretion and CCh administration caused enhanced secretion and a rise in [Ca2+]i. Castration did not affect the secretory mechanisms and the effect of CCh on the glandular cells in the small lobes of both male and female glands. The present study points to the possibility that sex hormones may control the functioning or expression of muscarinic receptors in the Harderian gland of the golden hamster.

Animals↗
PubMed1983

Effects of castration and adrenalectomy on in vitro rates of tryptophan hydroxylation and levels of serotonin in microdissected brain nuclei of adult male rats.

Rates of 5-hydroxytryptophan (5-HTP) synthesis and levels of serotonin (5-HT) were measured in microdissected brain nuclei following castration or adrenalectomy of adult male rats. Fourteen days following gonadectomy, 5-HTP synthesis decreased in the nucleus raphe dorsalis (DR) and nucleus centralis superior (NCS), while levels of 5-HT were unchanged in the 7 brain nuclei examined. Administration of testosterone to castrated rats not only did not reverse the castration-induced decrease in 5-HTP synthesis in the DR and NCS, but also decreased 5-HT synthesis in the nucleus amygdaloideus centralis (AGC) and the nucleus septalis lateralis (LS). Following administration of testosterone, 5-HT levels were unchanged. 10 days following bilateral adrenalectomy, 5-HTP synthesis increased in the NCS and the median eminence. Levels of 5-HT increased only in the median eminence. The increased 5-HTP synthesis and 5-HT levels following adrenalectomy were not reversed by corticosterone administration. In addition, these selective changes in 5-HT metabolism did not result from hormonal effects on the availability of tryptophan to the brain. We conclude that there are subsets of serotonergic neurons in rat central nervous system which respond uniquely to removal of the gonads and adrenals. Furthermore, the dissociation between serum and brain tryptophan concentrations and changes in rates of 5-HTP synthesis argue against tryptophan availability as being a primary determinant of 5-HT biosynthesis and for a direct endocrine central nervous system interaction with serotonergic neurons.

5-Hydroxytryptophan↗
PubMed1989

Pineal lysosomal enzymes in the Syrian hamster: circadian rhythm and effects of castration or short photoperiod treatment.

A circadian rhythm in acid phosphatase and hexosaminidase was found in adult male hamsters exposed to a long photoperiod (14:10 h light/dark [LD]; lights on 06.00 h) and killed at 08.00, 14.00, 20.00, 02.00, 04.00, 05.50 and 0.615 h. Hexosaminidase and beta-glucuronidase activity at 02.00, 04.00 and 05.50 h (values pooled for these times before lights on) were significantly elevated compared to enzyme activity at 06.15 and 08.00 h (pooled values after lights on), suggesting a fall in activity associated with lights on. Hypogonadism was induced in female Syrian hamsters by exposure to a short photoperiod (10:14 h LD) until a majority of them were vaginally acyclic. Pineal lysosomal enzyme activities (acid phosphatase, beta-glucuronidase, hexosaminidase, alpha-arabinosidase and beta-galactosidase) were significantly elevated in short photoperiod-exposed animals compared to animals in 14:10 LD, when measured near the middle of the light phase. In the third experiment, castrated animals were used to determine if lowered androgen levels might also affect pineal lysosomal enzyme activity. The results indicated that light phase beta-glucuronidase, hexosaminidase and beta-glucosidase activities were lower in castrated males compared to their intact controls. In summary, these results demonstrate that (1) lysosomal enzyme activity is present in the Syrian hamster pineal, (2) changes can be observed which suggest involvement of this activity in pineal function and, (3) a circadian rhythm in enzyme activity is present with peak activity occurring during the night. In the short photoperiod and castration experiments, the changes in lysosomal enzyme activity could reflect either a hormonal manipulation or a change in circadian regulation of enzyme activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1983

Androgen control of male sex behavior in the crested newt (Triturus cristatus carnifex Laur.): castration and sex steroid administration.

Castration significantly lowers serum testosterone in sexually active male Triturus cristatus. Replacement therapy by implants of testosterone in silastic capsules elevates the serum testosterone level to higher values than normal. Sex behavior is depressed by castration and partially reinstated by replacement therapy with testosterone. 5 alpha-dihydrotestosterone was the only testosterone metabolite showing some behavioral effectiveness in castrates; estradiol and 5 beta-dihydrotestosterone failed to elicit sex behavior.

Androgens↗
PubMed1984

Differential maintenance of penile responses and copulatory behavior by gonadal hormones in castrated male rats.

Sexually experienced male rats were castrated and immediately received implants of Silastic tubing containing either testosterone (T), dihydrotestosterone (DHT), estradiol (E), or nothing (blank). The ability of these hormone treatments to maintain precastration levels of copulatory behavior and ex copula penile responses was assessed for 40 days after castration. Throughout the study T- and E-treated males, but not males with DHT or blank implants, maintained normal copulatory behavior. In contrast males treated with T and DHT, but not E or blanks, maintained penile responses ex copula. In blank-treated males, penile-response latencies increased more rapidly than did intromission latencies. These results, together with those of previous studies, appear to rule out a role for estradiol and reinforce the role of androgens in the activation of rats' penile-response potential ex copula. Similarly, the results support the conclusion that in castrated male rats estradiol treatment is sufficient for the activation of masculine copulatory behavior, and that the penile actions necessary for intromission are not dependent on androgen. Thus, the evocability of penile actions and their relative androgen dependence are context sensitive.

Animals↗
PubMed1983

Effect of castration on the metabolism of androgens in rat skeletal muscle.

The metabolic conversion of testosterone and 17 beta-hydroxy-5 alpha-andro-stan-3-one by cell fractions from skeletal muscle was examined. Little or no conversion of testosterone to 17 beta-hydroxy-5 alpha-androstan-3-one is observed with any skeletal muscle fraction studied. The cytosol from all muscles examined contained substantial levels of the enzyme 3 alpha-hydroxysteroid oxidoreductase, which converts 17 beta-hydroxy-5 alpha-androstan-3-one to 5 alpha-androstane-3,17 beta-diol. The Km of the reaction in the three muscles (extensor digitorum longus, soleus and levator ani) is in the order of 3-6 X 10(-6) M. Following castration, there is no significant change in the Km value of this reaction in any of the muscles. The Vmax of the conversion in the extensor digitorum longus and soleus are similar (in the order of 2.0 X 10(-11) mol/mg per min) and castration has no significant effect on Vmax in either of these muscles. Vmax is significantly lower for the levator ani (3.4 X 10(-12) mol/mg per min) than for the extensor digitorum longus and soleus. Following castration the Vmax for the levator ani undergoes a significant rise which peaks at 3 days.

Animals↗
PubMed1984

The effect of steroids on the size heterogeneity of pituitary prolactin in castrate male rats.

Male Sprague-Dawley rats were castrated and given daily sc. injections of estradiol (E2, 10 micrograms/day), testosterone propionate (TP, 1.0 mg/day), dihydrotestosterone (DHT, 1.0 mg/day) or sesame oil (SO, 0.2 ml/day). A group of sham castrate males received daily sc. injections of SO (0.2 ml/day). On day 8 of steroid treatment animals were decapitated and anterior pituitaries were removed and hemisected. Each half was homogenized in PBS buffer (0.01 M Na2HPO4-NaH2PO4; 0.14 M NaCl; 0.1% bovine serum albumin) at either pH 7.6 or 10.6. Homogenates were chromatographed on Sephadex G-100 columns and eluted fractions were assayed for prolactin (PRL) by RIA. Four immunoreactive forms of PRL, designated as "void volume," "big big," "big" and "little," were eluted from the pituitary homogenates of each experimental group. Homogenates obtained at pH 7.6 contained a greater percentage of PRL in the "void volume" and less activity in the "big" and "little" forms than pH 10.6 homogenates in all experimental groups. Pituitaries from SO- and TP-treated castrate animals contained significantly greater percentages of activity in the "void volume" at pH 7.6 compared to the other groups. At pH 10.6, the pituitary homogenates from the E2-treated group eluted a significantly greater percentage of "big" PRL and a smaller percentage of "little" PRL compared to all other groups. These findings suggest that androgenic and estrogenic steroids may play a role in the pituitary PRL molecular size profile of the male rat.

Animals↗
PubMed1982

Biphasic effect of estradiol on luteinizing hormone response to gonadotropin-releasing hormone in castrated men.

This study was designed to investigate the possibility that in men estradiol (E2) has a stimulatory effect on the gonadotropin response to GnRH. Nine castrated adult men, who presented extremely low testosterone (T) concentrations, received 5 mg/day estradiol benzoate (E2B) i.m. every 24 hr for several days, starting 5 days after orchidectomy. During E2B treatment the pituitary responsiveness to GnRH (100 micrograms given as an iv bolus) was tested after 24, 48, 72, 96, 120, and 144 hrs of E2B administration. The pituitary responsiveness to GnRH was also tested in untreated men from day 5 to day 10 following bilateral orchidectomy. In the E2B-treated subjects the increased serum estradiol concentrations induced an initial decrease and a subsequent increase of the LH response to GnRH. The responses were decreased after 24 hr of treatment; thereafter, the LH responses were progressively increased and were markedly augmented after 120 hr of E2B treatment. On the contrary, during treatment the FSH response to GnRH was preferentially blunted. In the untreated castrated men the LH and FSH responses to GnRH increased progressively from day 5 to day 10 after orchidectomy, but decreased responses were never observed during this period of observation. The maximum LH concentrations, which occurred at 30-60 min following GnRH in untreated castrated men, did not occur until 120-150 min in the E2B treated men.

Aged↗
PubMed1975

Lordosis behavior and mounting behavior in male rats: effects of castration and treatment with estradiol benzoate or testosterone propionate.

Male rats were selected for showing or not showing lordosis in response to manual stimulation. They were subsequently tested for mounting behavior with receptive females and for lordosis behavior in response to manual stimulation and to male mounting. Males showing lordosis as intacts displayed this behavior more readily following castration or castration and treatment with estradiol benzoate or testosterone propionate than males which did not show lordosis before castration. No group differences in mounting behavior could be detected under any of the endocrine conditions studied. It is suggested that the neural mechanisms mediated mounting and lordosis are dissociated and that individual differences in the occurrence of lordosis in male rats are due to differences in neural sensitivity to estrogen.

Animals↗
PubMed1982

Effects of photoperiod and castration on post-fast food intake and body weight gain in golden hamsters.

This experiment examined the effects of photoperiod and castration of post-food-restriction food intake and body weight gain in male golden hamsters (Mesocricetus auratus). Hamsters were ether castrated or sham-operated and housed in a 14:10 light-dark (LD) or a 8:16 LD cycle for 8 weeks. All animals were restricted to a 6 g of chow per day for 13 days and then returned to ad lib feeding. Following food restriction the hamsters gained weight rapidly without overeating. The long photoperiod (LD 14:10) increased post-restriction weight gain in castrated hamsters but decreased weight gain in gonadally intact animals. These differences in body weight gain were associated with significant group differences in feed efficiency (grams weight gain per gram eaten). The results suggest that changes in energy utilization may be more important than changes in energy intake in the adaptation of hamsters to food restriction.

Adaptation, Physiological↗
PubMed1983

LHRH and rat avoidance behavior: influence of castration and testosterone.

Pretraining subcutaneous administration of a high dose of LHRH (100 micrograms/kg) to intact rats impaired acquisition of a conditioned avoidance response (CAR) in a two way shuttle box. Acquisition of a CAR was also decreased when LHRH was administered to castrated rats. LHRH antagonized the dose related impairment in acquisition and retention performance induced by testosterone in castrated animals. The results are discussed based on the interrelationships between castration, testosterone, LHRH and brain monoamines.

Animals↗
PubMed1984

Influence of castration and brain GABA levels in three strains of mice on aggression towards lactating intruders.

This study examined the relationship among aggression towards lactating intruders, castration and brain GABA levels in three strains of mice (C57, C3H and CBA). Both C57 and C3H (but not CBA) animals showed reduced attack latencies following castration. C57 mice showed the highest intensity of this behavior and the response was almost absent in the CBA strain. Considerable strain differences in brain GABA levels were observed. In particular the most aggressive C57 castrates had significantly higher levels of GABA in the hypothalamus, the olfactory bulbs and the amygdala. Such changes are not recorded in C3H or CBA strains of mice, which are both characterized by low levels of baseline aggression towards lactating intruders.

Aggression↗
PubMed1976

The possible mode of action of phostaglandins. XII. Differential effects of phostaglandin F2alpha in inducing premature evacuation of conceptos in the intact and castrated pregnant rat.

A single injection of 2.0 mg/kg prostaglandin F2alpha(PGF2alpha) on day 18 of pregnancy was consistent in inducing premature labor by 72 h following the injection. Conversely, castration before PGF2alpha on day 18 of pregnancy made the animals almost inert to PGF2alpha and only 20% of the treated animals showed premature evacuation of the conceptus. Injection of 10mug of estradiol cyclopentylpropionate (ECP) on day 18 was, however, found to be effective in emptying the gravid uteri of 100% castrated pregnants by 72 h. Indomethacin, a consistent inhibitor of prostaglandin biosynthesis and release, along with ECP in an identical experimental situation was found to be ineffective in reversing the ECP-induced premature parturition in castrated pregnants. The importance of intact ovary for the action of PGF2alpha concerning premature labor in rats has been discussed.

Animals↗
PubMed1978

Catecholamines in discrete areas of the hypothalamus of obese and castrated male rats.

Levels of norepinephrine (NE) and dopamine (DA) were measured in eight discrete regions of the hypothalamus in three groups of male rats; genetically obese (fafa), non-obese (FaFa) and castrated non-obese (FaFa). DA levels showed no significant differences among the groups in any of the regions. NE levels in the paraventricular nucleus (PVN) were significantly lower in the obese and castrated animals than in the normal animals. In the median eminence (ME), NE levels were significantly decreased for the castrated group. None of the other regions sampled showed significant differences in NE levels.

Animals↗