The effects of the administration of testosterone propionate alone or with phenobarbitone and of testosterone metabolites to neonatal female rats

The effects of graded doses of testosterone propionate administered to female rats on Day 4 of postnatal life have been determined. The incidence of failure of ovulation as adults was related to the dose. With increasing dosage over the range 1–100 μg no significant evidence of a progressive decrease in immunoassayable luteinizing hormone concentration in the plasma or anterior pituitary was obtained. The reported protective action of sodium phenobarbitone when administered with testosterone propionate could not be confirmed. Single injections of 100 μg of testosterone, dihydrotestosterone, 5 α-androstanediol, or a combination of the two latter compounds had no masculinizing effect. When the 17-β propionate derivatives of these compounds were administered at the same dose level only testosterone propionate had a masculinizing effect.     

Regulation of the pituitary 5 alpha-reductase activity by gonadotropin releasing hormone and testosterone in the adult male rat

Intact or castrated adult male rats were treated for nine days with GnRH (10 micrograms/day), the synthetic GnRH goserelin (100 micrograms/day) or the GnRH-antagonist Org 30276 (250 or 500 micrograms/day). In some series, 1 mg testosterone propionate was administered alone, or in combination with goserelin or Org 30276. The in vitro metabolism of [1 alpha,2 alpha-3H]testosterone by pituitary and hypothalamic homogenates was investigated in combination with the estimation of plasma concentrations of testosterone and gonadotropins. No qualitative or quantitative differences were observed in hypothalamic testosterone metabolism or in the pituitary 17 beta-hydroxysteroid dehydrogenase activity. Testosterone administration to intact male rats decreased the pituitary 5 alpha-reductase activity and LH, while administered to castrated rats, it was able to suppress totally the castration-induced increase of the 5 alpha-reductase activity and of the gonadotropin secretion. The drastic decrease of the plasma levels of testosterone, observed after a prolonged treatment with GnRH, goserelin or Org 30276 was not accompanied by an increased pituitary 5 alpha-reductase activity. Injected to castrated rats, it was observed that the castration-induced increase of the pituitary 5 alpha-reductase was further stimulated by GnRH, totally suppressed by goserelin and partially suppressed by Org 30276. Concomitant administration of goserelin or Org 30276 and testosterone propionate to castrated rats resulted in a further decrease of the pituitary 5 alpha-reductase activity, compared to the castrated, GnRH-analogue treated rats. These data indicate that the pituitary 5 alpha-reductase enzyme system is controlled by both direct steroidal and indirect GnRH-mediated mechanisms.     

Sickness-related odor communication signals as determinants of social behavior in rat: A role for inflammatory processes

Infected animals are avoided by conspecifics, suggesting that the inflammatory cascade may play a significant role in odor communication. Injection of male rats with the bacterial mimetic, lipopolysaccharide (LPS, 100 μg/kg, i.p.), decreased investigation through a wire-mesh partition between healthy male partners. This avoidance response was observed in adult males in response to soiled bedding collected from sick rats, regardless of whether LPS was injected peripherally (100 μg/kg, i.p.) or centrally (0.25 or 2.5 μg, icv). The release of sickness-related odor cues was dose-dependently blocked by icv infusion of the anti-inflammatory cytokine, interleukin-10 (IL-10; 20 or 200 ng), and reproduced by icv infusion of pro-inflammatory cytokine, IL-1β (5 or 50 ng). Subcutaneous pretreatment with either estradiol benzoate (20 μg/kg) or testosterone propionate (50 or 500 μg/kg) to adult males that were administered LPS inhibited release of aversive odor cues, but these hormones alone did not influence odor properties. Importantly, the avoidance response to sickness-related odor was not associated with changes in plasma corticosterone, testosterone, or IL-6 levels of odor donors. However, plasma IL-1β concentrations of sick animals was in fact predictive of aversive responses in conspecifics, suggesting that the inflammatory cascade, but not plasma steroid hormones, is likely to mediate aversive properties in odor that functions to signal illness state to conspecifics.     

Reduced gonadotropin release in response to progesterone or gonadotropin releasing hormone (GnRH) in old female rats

Ovariectomized rats that were 3–4, 12 or 22 months old were injected s.c. with 4 mg, of testosterone propionate and 3 days later were injected s.c. with 2.8 mg. progesterone or the oil vehicle. Blood samples were collected by heart puncture 5 hrs. later. Serum levels of LH and FSH decreased significantly as age increased. Progesterone significantly increased serum LH and FSH levels regardless of age. The increase in serum LH concentration attributed to progesterone was greatest in the young and least in the old rats. To determine if age effects were due to differences in pituitary response to GnRH, ovariectomized rats that were 2.5 to 23 months old were injected i.v. with GnRH at doses of 100 ng or 40 ng/100 g body weight or were primed with 25 mg progesterone and 50 μg estradiol-benzoate 3 days before an injection of 2 ng GnRH/100 g body weight. Blood was obtained by heart puncture before and 20 min. after GnRH. In each experiment serum LH levels significantly decreased with increasing age but were significantly elevated by GnRH. This increase in serum LH level in response to GnRH declined with increasing age. The data suggest that the elevation in serum LH level in response to GnRH declines as a result of aging in female rats and that this effect is independent of circulating ovarian steroid levels.     

Effects of testosterone metabolites on serum gonadotropin concentrations in immature male rats.

The ability of testosterone, androsterone, 5alpha-androstane-3alpha,17beta-diol, and 5alpha-androstane-3beta,17beta-diol to prevent the castration-induced rise in serum gonadotropin levels was investigated in immature male rats. Rats castrated at 30 days of age were treated once per day by subcutaneous injection of 12.5-100 mug of the steroid per 100 g body weight per day for 3 days, beginning on the day of castration. The animals were sacrificed 24 h after the last injection. Testosterone propionate, androsterone propionate, and 5alpha-androstane-3alpha,17beta-diol dipropionate were also tested at the approximate molar equivalent of 100 mug of the free alcohol form per 100 g body weight per day. Testosterone propionate and 5alpha-androstane-3alpha,17beta-diol were the only compounds tested that prevented the castration induced rise in luteinizing hormone (LH) concentrations. Testosterone propionate also inhibited the rise in follicle stimulating hormone (FSH) concentrations whereas 5alpha-androstane-3alpha,17beta-diol inhibited the rise in FSH in one but not in another experiment. These were the only compounds tested that affected serum FSH concentrations. The lower doses of testosterone tested significantly increased serum LH, but not FSH concentrations compared to castrate control animals. The highest dose tested partially inhibited the rise in serum LH concentrations. Both androsterone and androsterone propionate maintained ventral prostate weights. Although neither compound prevented the castration induced rise in serum LH, two groups receiving androsterone had serum LH concentrations significantly lower than the castrate control group. 5alpha-Androstane-3beta,17beta-diol and 5alpha-androstane-3alpha,17beta-diol dipropionate failed to maintain ventral prostate weights or prevent the rise in serum gonadotropin levels. These results indicate that 5alpha-androstane-3alpha,17beta-diol is capable of preventing the castration induced rise in serum LH concentrations in the immature male rat and thus may participate in the regulation of LH secretion in these animals.     

The influence of testosterone on the alkaline proteolytic activity in rat skeletal muscle

The effects of testectomy and subsequent administration of testosterone propionate on the activity of the alkaline proteinases in rat skeletal muscle were investigated. Castration of the mature rat was followed by a short-term delay in protein accretion in skeletal muscle tissue as measured by the protein/DNA ratio and was paralleled by a 2–3 fold increase in specific activity of the alkaline proteinase(s). This increase of proteolytic activity was equally significant when expressed relative to μg DNA. Although the gain in body weight was significantly lower in the castrated rats, nevertheless the protein/DNA ratio in muscle after 6 weeks approximated the values of sham-operated control rats without normalization of the proteolytic activity.Treatment of the castrated rats with testosterone propoinate resulted in restoring normal levels of previously elevated levels of alkaline proteolytic activity in muscle tissue. The normalization of enzyme activity as well as protein accretion in muscle was dose-dependent. Treatment of the rats with a low dose (0.1 mg/day) of testosterone propionate failed to restore the proteolytic activity, but led to a small increase of the protein/DNA ratio as well as to a progressive increase in body weight. These data indicate a regulatory role of testosterone in the adaptive behaviour of the alkaline proteolytic system in rat skeletal muscle.     

Restorative effect of various androgens on copulatory behavior of the male golden hamster

Adult male hamsters were castrated, and four weeks later, after a single mating test, began receiving daily 100 μg injections of testosterone (T), androstenedione (AD), or testosterone propionate (TP). Mating tests were conducted at regular intervals during the eight week treatment period. Results indicated the superiority of TP in reinstating intromissions and ejaculations. The T and AD groups did not differ on any of the measures, a result which agrees with previous similar experiments using rats.     

Inhibition of estrogen-activated sexual behavior by androgens

Experiments to determine the potential of androgen to inhibit estrogen-activated female sexual behavior in rats were conducted. Treatment with either testosterone propionate (0.8 or 1.6 mg/day) or dihydrotestosterone propionate (0.2, 0.4, or 0.8 mg/day) significantly reduced the incidence of lordosis in ovariectomized females receiving estradiol benzoate (1 microgram/day). A similar suppression of estrogen-activated lordosis by testosterone was observed in castrated male rats. Flutamide, an androgen-receptor blocker, prevented the inhibition of lordosis by testosterone in females, indicating that the interaction of testosterone or a metabolite with an androgen receptor may be an important feature of this inhibition. Furthermore, the ability of dihydrotestosterone to inhibit lordosis at lower doses than testosterone suggests that the conversion of testosterone to dihydrotestosterone may also be necessary. These experiments demonstrate the potential of testosterone to inhibit the occurrence of female sexual behavior in rats, in contrast to its established facilitative effect on this behavior.     

Oleuropein supplementation increases urinary noradrenaline and testicular testosterone levels and decreases plasma corticosterone level in rats fed high-protein diet

The effects of oleuropein, a phenolic compound in extra virgin olive oil, on protein metabolism were investigated by measuring testicular testosterone and plasma corticosterone levels in rats fed diets with different protein levels. In Experiment 1, rats were fed experimental diets with different protein levels (40, 25 and 10 g/100 g casein) with or without 0.1 g/100 g oleuropein. After 28 days of feeding, the testosterone level in the testis was significantly higher and the plasma corticosterone level was significantly lower in rats fed the 40% casein diet with oleuropein than in those fed the same diet without oleuropein. The urinary noradrenaline level, nitrogen balance and hepatic arginase activity were significantly higher in rats fed the 40% casein diet with oleuropein supplementation than in those fed the 40% casein diet without oleuropein supplementation. In Experiment 2, the effects of oleuropein aglycone (a major phenolic compound in extra virgin olive oil and the absorbed form of oleuropein ingested in the gastrointestinal tracts) on the secretion of luteinizing hormone (LH) from the pituitary gland, which regulates testosterone production in the testis, were investigated in anesthetized rats. Plasma LH level increased dose dependently after the administration of oleuropein aglycone (P<.001, r= 0.691). These findings suggest that dietary supplementation with 0.1 g/100 g oleuropein alters the levels of hormones associated with protein anabolism by increasing urinary noradrenaline and testicular testosterone levels and decreasing plasma corticosterone level in rats fed a high-protein diet.     

Testosterone increases TSH-beta mRNA, and modulates alpha-subunit mRNA differentially in mouse thyrotropic tumor and castrate rat pituitary.

TSH, LH and FSH, the three pituitary glycoprotein hormones, are each composed of a common alpha-subunit and a hormone specific beta-subunit. Testosterone is known to regulate all three intact hormones differently in the rodent. However, there is only one gene encoding the common alpha-subunit. In order to elucidate the effects of testosterone on TSH subunit synthesis and its regulation of the common alpha-subunit, two in vivo models were studied: castrate rat pituitary was used as a gonadotropin-enriched tissue; and mouse thyrotropic tumor was used as a thyrotropin-enriched tissue. Male castrate rats were treated with testosterone propionate, 500 micrograms/100 g BW, sc, for 11 days. Testosterone increased plasma TSH to 131% of control values (P less than 0.02), while plasma LH fell to undetectable levels, and plasma alpha-subunit fell to 14% of control values (P less than 0.001). Testosterone increased TSH-beta mRNA to 237% of control values (P less than 0.02), while alpha-subunit mRNA fell to 20% of control values (P less than 0.001). Hypothyroid mice bearing thyrotropic tumors were treated with testosterone propionate, 150 micrograms/100 g BW, sc, for 11 days. In this model plasma TSH-beta and alpha-subunit concentrations are 1000-fold higher than in non-tumor bearing animals, and the contribution of pituitary gonadotropes to plasma subunit concentrations is negligible. "Total" TSH-beta and alpha-subunit concentrations were estimated as one-half of intact TSH plus the respective free subunit concentration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lordosis behavior in castrated male rats treated with estradiol benzoate or testosterone propionate in combination with an estrogen antagonist, MER-25, and in intact male rats

Lordosis behavior could be elicited by manual stimulation in castrated male rats after treatment with estradiol benzoate (15 μg for 10 days) or testosterone propionate (1 or 3 mg for 10 days). The effect was antagonized by treatment with the estrogen antagonist MER-25 (10mg for 10 days). Prolonged treatment with testosterone propionate (1 mg for 26 days) resulted in display of male (nine of ten rats) as well as female (seven of ten rats) sexual behavior. Eleven of 32 intact male rats (age 120 days) and 22 of 37 other intact males (age 75 days) displayed lordosis in response to manual stimulation without hormonal treatment. Seven intact males which showed lordosis without hormone treatment were injected with MER-25 (10 mg/day × 10 days) and lordosis was abolished in six cases. The results suggest that estrogen is involved in the regulation of lordosis behavior in TP-treated and intact male rats.     

Sex steroids modulate rat anterior pituitary and liver iodothyronine deiodinase activities.

In this study, we investigated the sex hormone regulation of 5'-iodothyronine deiodinase activity, which is responsible for enzymatic conversion of thyroxine into the bioactive form, triiodothyronine. Pituitary homogenates and liver microsomes from: 1) ovariectomized rats injected with 17-beta-estradiol benzoate and/or progesterone (0.7 and 250 microg/100 g body weight, respectively, subcutaneously, over 10 days); 2) male castrated rats treated or not with 0.4 mg/100 g body weight testosterone propionate, intramuscular, over 7 days, were assayed for type 1 and type 2 deiodinase activity in the pituitary. Enzyme activities were measured by release of (125)I from deiodination of (125)I reverse triiodothyronine under varying assay conditions. Estrogen stimulated anterior pituitary and liver type 1 deiodinase activity in ovariectomized rats (45 and 30 %, p < 0.05). Progesterone inhibited the liver enzyme (40 %, p < 0.05), and had no effect on the pituitary, but in both tissues, blocked estrogen stimulatory effect on type 1 deiodinase. In males, testosterone normalized the reduced liver type 1 deiodinase of castrated rats. However, in the pituitary, castration increased (50 %) type 1 deiodinase independent of testosterone treatment, suggesting the existence of a inhibitory testicular regulator of pituitary type 1 enzyme. Treatments did not alter pituitary type 2 deiodinase activity. In conclusion, gonads and sex steroids differentially modulate type 1 deiodinase activity in rat pituitary and liver.     

Stimulation of spermatocyte development in prepubertal rats by the Sertoli cell steroid, 3 alpha-hydroxy-4-pregnen-20-one

The effect of 3 alpha-hydroxy-4-pregnen-3-one (3HP), a Sertoli cell steroid, on spermatogenesis was examined in normal and gonadotropin-suppressed rats, through s.c. as well as direct intratesticular injections. Early experiments employing normal prepubertal male rats indicated that 3HP, when administered at 65 micrograms/100 g BW daily for 15 days, was capable of stimulating pachytene spermatocyte number to 149% of untreated control numbers. It was of interest to determine if this effect could be amplified in gonadotropin-suppressed animals. Neonatally estrogenized rats (500 micrograms estradiol benzoate in 0.1 ml oil at 2 days) were treated on alternate days with 3HP (100 micrograms/100 g BW) for 3 wk, starting at 7 days of age. This treatment significantly increased the number of spermatocytes per tubule cross section from 17.3 +/- 1.9 (in estradiol benzoate-only animals) to 47.1 +/- 7.9 (p less than 0.01). In a similar study, 100 micrograms/100 g BW of testosterone propionate could stimulate spermatocyte number to only 15.1 +/- 2.2 cells per tubule cross section versus estradiol benzoate-only numbers. A single intratesticular injection of 3HP (2 ng in 2.0 microliters oil) in Methallibure-treated rats resulted in a significant increase in late pachytene spermatocyte numbers from 0.77 +/- 0.12 in Methallibure-only-treated rats to 1.70 +/- 0.10 (p less than 0.001) cells per tubule cross section in 28-day-old rats. However, in this study, no other progesterone metabolite or androgenic steroid (testosterone, 5 alpha-dihydrotestosterone, or 5 alpha-androstan-3 alpha, 17 beta-diol) tested was capable of this level of germ cell stimulation. In conclusion, 3HP appears to have a direct effect on germ cell development within the testis at levels much lower than those shown to be effective for androgens. It does not appear that this effect is mediated through the conversion of 3HP to any C21 or C19 steroids, and appears to be the first report of a Sertoli cell steroid with a possible role in the process of mammalian spermatogenesis.     

The effect of testosterone on serum gonadotropins of castrated rats kept under different lighting conditions.

Testosterone feedback sensitivity was measured as the ability of testosterone propionate to decrease serum LH and FSH of long-term castrated (4 wk) rats under four different lighting conditions: periodic light (12L:12D), constant light (LL), constant darkness (DD), and dim night illumination (1 lx) with a 12L:12D photoperiod. Rats were exposed to the different lighting conditions for 1 wk, during which they received daily testosterone propionate (125 micrograms or 250 micrograms s.c.). At the end of the experiment the rats were decapitated at 1100 h, and serum gonadotropin levels were measured by RIA. Serum LH of the rats kept under LL was reduced to the level of the intact rats with the smaller testosterone dose (125 micrograms/day). Under all other lighting conditions only the large dose (250 micrograms/day) was able to restore the serum LH concentration to the level of the intact rats. Serum FSH was restored only partially, and the effect was the same with both doses and similar under all lighting conditions. We conclude that the increase in testosterone negative feedback sensitivity was not caused by the lack of periodicity of illumination alone, but that sufficient intensity of lighting throughout the 24 h was needed as well.     

Responses of plasma apolipoproteins to gonadectomy and androgen substitution in male rats

To obtain information on testosterone effects on plasma apolipoproteins, the amount and composition of apo-proteins in lipoproteins of 5 density classes (VLDL, LDL, HDL2b, HDL2a, HDL3) was estimated in 3 groups of adult male rats: normal control rats, castrated rats, and rats injected daily with testosterone propionate (200 micrograms/day) for one week after castration. Apoproteins were separated by sodium dodecylsulfate polyacrylamide gel electrophoresis after ultracentrifugation of plasma, and determined colorimetrically. Total amount of apoprotein carried in LDL (d = 1.006-1.063 g/ml) and HDL2b (d = 1.063-1.100 g/ml) was higher in castrated than in control rats, but was not significantly different from controls in testosterone substituted rats. LDL apo B and HDL2b apo E were higher in castrated than in normal rats; control levels were observed in androgen substituted rats. Except for a greatly increased relative amount of HDL2b apo E, and a decreased percentage of HDL2b apo A-I in castrated rats, there were no significant alterations by castration of apoprotein composition of the lipoproteins. The results raise the question whether the androgenic state might affect processes related to the effects of plasma LDL apo B and HDL apo E.     

Estrogen-activated sexual behavior in male rats

Daily injections of 100 μg estradiol benzoate activated the whole pattern of sexual behavior in castrated sexually experienced male rats. If compared to rats treated daily with 100 μg testosterone propionate, the estrogen-treated males tended to have longer latencies and more mounts and intromissions prior to ejaculation. Fifty micrograms of estradiol benzoate stimulated the display of mounts and intromissions in prepuberally castrated male rats. No peripheral effects of the estrogen treatment were noted. These results suggest that estrogen has central “androgen-like” effects, but no such effects in the periphery. Estrogen treatment (5, 50, and 200 μg/kg for 3 weeks) of intact sexually experienced male rats resulted in testicular atrophy and loss of body weight, but had no significant effects on the sexual behavior.     

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.     

Effect of neonatal testosterone and oestradiol treatment on the development of the hypothalamo-hypophysial axis in the female rat.

The hypothalamic LH-RH content and the concentrations of pituitary and plasma LH were measured at various ages in female rats treated daily with 10 micrograms testosterone propionate or 10 micrograms oestradiol-17beta from birth to Day 15. Persistent vaginal oestrus was induced in all the treated rats. Both hormones significantly reduced the hypothalamic LH-RH content and pituitary and plasma LH concentrations. Hypothalamic LH-RH increased after cessation of treatment but pituitary LH did not return to normal levels. Plasma LH levels were significantly lower than those in control rats. It is concluded that testosterone propionate and oestradiol-17beta (1) have a direct negative feed-back influence on the hypothalamus in the neonatal female rat; (2) alter the normal pattern of plasma and pituitary LH in developing female rats; (3) prevent the cyclic secretion of plasma LH after maturity; and (4) probably cause a chronic impairment in the release of LH-RH.     

A comparison of the effects of methyltrienolone (R 1881) and 5 alpha-dihydrotestosterone on sexual behavior of castrated male rats.

The synthetic steroid methyltrienolone (R 1881) binds specifically with high affinity to intracellular androgen receptors and is not metabolized to androstanediol. Administration of R 1881 (1 mg/day) to castrated male rats facilitated intromission in significantly more animals than did 5α-dihydrotestosterone (DHT) (1 mg/day); however, the percentage of animals ejaculating and the pattern of behavior displayed were equivalent in the two groups. Combined administration of estradiol benzoate (EB) (2 μg/day) plus either R 1881 or DHT further facilitated males' sexual performance to levels previously seen in castrated male rats of the same strain when given testosterone propionate (TP). The results suggest that conversion of DHT to 3α- or 3β-androstanediol neither detracts from nor contributes to its ability to activate sexual behavior in the male rat.     

Induction of vaginal mucification in rats with testosterone and 17beta-hydroxy-5alpha-androstan-3-one.

Based on histological criteria, Kingsley and Bogdanove (3) reported that the benzoate ester of 17beta-hydroxy-5alpha-androstan-3-one (5alpha-DHT), unlike testosterone propionate, is unable to induce vaginal mucification when given subcutaneously to rats. In contrats, Kennedy (4) found in estrogen-pretreated rats that both 5alpha-DHT and testosterone induced vaginal mucification as indicated by increased vaginal sialic acid concentration.To determine if esterification of these androgens altered their ability to induce vaginal mucification, ovariectomized rats, pretreated for 3 days with 0.25 mug estradiol-17beta, were treated for 8 days with either sesame oil or 7 mumoles of testosterone, 5alpha-DHT and their respective propionate and benzoate esters. All treatments except 5-alpha-DHT benzoate increased vaginal weight and vaginal mucification, as assessed histochemically and biochemically. 5alpha-DHT propionate was less effective than 5alpha-DHT while testosterone benzoate, but not propionate was less effective than testosterone. To determine if estrogens are necessary for the vaginal effects of androgens, ovariectomized and ovariectomized-adrenalectomized rats were treated with testosterone or 5alpha-DHT. Adrenalectomy did not significantly affect the vaginal response to either androgen. It is therefore concluded that androgens are capable of inducing vaginal mucification in the absence of estrogens.