Estrogen-activated sexual behavior in male rats (original) (raw)
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Hormones and Behavior, 1970
Castrated rats given a single large injection of an ether of testoster one, SC-16148, copulated more frequently and for a longer period of time than rats administered an equivalent amount of testosterone propionate. Latency to first ejaculation following treatment was shortest in the testo sterone propionate treated animals. The maximal behavioral response to each steroid was similar in time to peak responses of androgen sensitive tissue as measured in a separate study. Saunders (1966) found that the substitution of a trimethylsilyl ether for the propionic acid moiety in testosterone propionate resulted in a peculiar ly long-acting androgenic compo und. He reported a maximum physiological response in the seminal vesicles, ventral prostate, and levator ani muscle of castrated rats 20-30 days after a single injection of the 17-trimethylsilyl ether of testosterone (SC-16148). The duration of the effect and the magnitude of the response were greater than those produced after administration of the same amount of testosterone propionate, which produced a maximum re sponse in 7-10 days. The purpose of this study was to determine whether SC-16148 also has a long-acting effect on the sexual response of castrated males to estrous females. METHODS Thirty male rats of the Long-Evans strain were used as experimental subjects; they were 70 days old at the beginning of the experiment. Stimulus females from the Long-Evans and Sprague-Dawley strains were brought into behavioral estrus by a single subcutaneous injection of 333 f.1g estradiol benzo ate in oil, 1 48-72 hours before testing. Each female received an injection
Endocrinology, 2012
Low sexual desire concomitant with feelings of distress is reported in naturally and surgically menopausal women. A combination of estradiol (E2) and testosterone (T) restores sexual desire and interest in these women. The central mechanisms by which E2 and T act to restore desire are poorly understood. Here we examined the effect of chronic treatment with testosterone propionate (TP) administered by a sc SILASTIC brand capsule in aged ovary-intact female rats. Females were first treated with TP alone, followed by a second phase when TP was administered in combination with estradiol benzoate (EB; 10 μg) by sc injection 48 h prior to testing (EB+TP). Each phase consisted of 5 test days at 4-d intervals. Appetitive and consummatory female sexual behaviors were observed in bilevel chambers, and plasma E2 and T concentrations were measured with ELISA. Sexual solicitations and hops and darts were facilitated by the highest TP dose, and the lordosis quotient was increased by the two highe...
Activation of sexual reflexes of male rats by dihydrotestosterone but not estrogen
Physiology & Behavior, 1979
Activation of sexual reflexes of male rats by dihydrotestosterone but not estrogen. PHYSIOL. BEHAV. 23(1) [107][108][109] 1979.--Previous studies have shown that withdrawal and administration of testosterone propionate (TP) has a quantitative influence on sexual reflexes which parallels changes in copulatory activity following castration and administration of TP. The present study involving castrated spinal male rats explored further this parallel, focusing on the effects on sexual reflexes of the administration of dihydrotestosterone propionate (DHTP) and estradiol benzoate (EB), both of which can activate sexual behavior in spinally intact castrated male rats, but only if given in very large doses for a prolonged period of time. A parallel effect on reflexes and behavior was not found inasmuch as DHTP activated sexual reflexes at a dose (200 p.g daily) considerably below that needed to activate behavior, and EB did not appreciably activate reflexes, even after prolonged treatment at levels (100-200 p.g) higher than necessary to activate behavior. The results, with EB in particular, point out that the display of intromissive and ejaculatory patterns in rats may not involve spinal neural mechanisms that are customarily associated with these behavioral patterns.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
The effects of castration and hormone replacement on the acquisition of a leverpress Sidman avoidance task were examined. Sixty male rats were assigned randomly to one of five groups: (1) castration with estradiol treatment, (2) castration with progesterone treatment, (3) castration with estradiol and progesterone treatment, (4) castration with saline treatment, and (5) sham castration with saline treatment. Serum hormone concentrations were determined by radioimmunoassay. While serum assays indicated an increase of at least 600% to 3,300% for progesterone and estrogen levels, respectively, the results did not reveal any significant castration or hormone effects on the acquisition of the avoidance task.
Effects of 17β-aminoestrogens on the sexual behavior of female rats
Physiology & Behavior, 2009
Keywords: 17β-aminoestrogens 17β-estradiol Estradiol benzoate Female rat Sexual behavior Lordosis 17β-aminoestrogens (AEs) produce anticoagulant effects in rats contrasting with 17β-estradiol (E 2 ) procoagulant effects, their estrogenic effects are similar to E 2 , decreasing serum luteinizing hormone (LH), increasing uterine weight (Uw), activate transcription through the ERα and ERβ receptors and pentolame induces progesterone (P) receptors in the anterior pituitary of ovariectomized (Ovx) rats similarly to E 2 , suggesting possible effects on female rats' sexual behavior. This work evaluated the AEs prolame, butolame, pentolame compared to E 2 and estradiol benzoate (EB) as facilitators on the rat lordotic behavior. Dose-response curves were performed in rats by single subcutaneous (s.c.) injection (time zero) of: E 2 (≈0.3, 3, 30, 60, 300 µg/kg); EB (≈0.4, 4, 40, 80, 400 µg/kg); prolame, butolame, pentolame (≈40, 400, 2000 or 4000 mg/kg), vehicle (corn oil; 300 µL/day; ≈1.2 mL/kg) as control; 24 h after, P (1 mg/rat in 100 µL of corn oil; ≈4 to 5 mg/kg) was administered, and 5 to 7 h later LQ was evaluated (number of lordosis displays / number of mounts × 100). E 2 , EB and AEs followed by P administration, induced lordosis in a dose-dependent manner. Prolame induced an LQEmax of 92, butolame 85, EB 81, pentolame 44 and E 2 43. The most potent was EB (LQED50 of 4.1 ± 0.5 µg/kg); then E 2 10 µg ± 2.2/kg; prolame 268± 19 µg/kg; butolame 402 ± 21 µg/kg, and pentolame 1037 ± 28 µg/kg. The AEs LQ potency decreases as length substitution on the amine group in C-17 increases. AEs LQDE50 values correlate with previous Uw DE50, LH ID50 and binding studies indicates mediation of the response by estrogen receptors. AEs facilitate sexual behavior of Ovx rats as partial estrogenic agonists.
Steroid regulation of sexual behavior
Journal of Steroid Biochemistry, 1976
Experimental data on rats and rabbits are reviewed, in support of the idea that estrogen is involved in the control both of male and female sexual behavior in these species. Female sexual behavior is stimulated by estrogen alone or estrogen in combination with progesterone. It can, however, also be induced by aromatizable, but not by non-aromatizable, androgens. Masculine sexual behavior is stimulated by aromatizable androgens or by non-aromatizable androgens combined with estrogen. The stimulatory effect of androgen on masculine sexual behavior is blocked by some aromatization blockers. This blocking effect can be reversed by estrogen. It is suggested that under normal conditions estrogens and androgens interact in producing sexual behavior.
Physiology & Behavior, 2008
Testosterone, androstenedione, and 5α-dihydrotestosterone on male sexual behavior and penile spines in the hamster. PHYSIOL BEHAV XX (6) 000-000, 2007. -The expression of masculine sexual behavior (MSB) in male hamsters is optimally stimulated by aromatizable androgens like androstenedione (AD) and testosterone (T), while the non-aromatizable androgen, 5α-dihydrotestosterone (DHT), exerting potent androgenic peripheral effects, only in high doses maintains MSB after castration. No data exist on the ability of these androgens to restore long intromissions after castration. In this study, AD, T, and DHT were administered to four-week gonadectomized, sexually experienced male hamsters, for three weeks, in doses of 25 μg/day or up to 1000 μg/day to compare their potency in restoring MSB, penile size, and penile spines growth. Plasma levels of these steroids and the metabolites estrone and estradiol, were determined at the end of the treatment period. Gonadectomy completely suppressed MSB and induced a regression of penile spines. AD was more potent than T in restoring MSB, ejaculatory behavior being displayed by most castrated subjects with a lower dose of AD (50 μg/day) than of T (300 μg/day), and long intromissions being shown by all AD-treated castrated hamsters but only by 20% of T-treated ones, when doses of 1000 μg/day were given. DHT did not stimulate any copulatory response. The three androgens, even at the lowest dose, partially stimulated penis and penile epithelium growth, DHT showing the highest potency. Treatment of castrated hamsters with AD (50 μg/day), restored steroid levels to similar values as those of intact animals. These results show that AD and T restored MSB even with a partial stimulation of penile spines growth, AD being more potent than T. In contrast, DHT did not restore MSB in the hamster in spite of its peripheral androgenic potency.
Biology of Reproduction, 1993
The synthetic steroid 7a-methyl-19-nortestosterone (MENT) binds with high affinity to the androgen receptor and exerts biological effects at some peripheral target tissues with a potency greater than that of naturally occurring androgens. In vivo, MENT does not undergo enzymatic 5a-reduction and as a consequence, its biologic action on prostate and other organs of the male reproductive tract is not amplified as is that of testosterone (T). Thus, in castrated rats, a dose of MENT that will maintain normal muscle mass and gonadotropin levels will not maintain normal prostate and seminal vesicle weights. To investigate the ability of MENT to restore male sexual behavior in castrated rats, varying doses of MENT acetate were administered for 4 wk by use of s.c. mini-osmotic pumps. Animals treated with T acetate (200 jtg/day) and nontreated intact animals served as positive controls, while a group of animals receiving vehicle alone were the negative controls. Steroid acetates are rapidly converted to T and MENT in blood. Appropriate steroid delivery was assessed by measurement of serum androgen concentrations. Male behavioral parameters were recorded twice per week. At the end of treatment, the weights of sex accessory organs were also recorded. The administration of MENT acetate at daily doses of 100 utg and 10 jig induced full copulatory behavior in a manner similar to that observed with doses of 200 jig T acetate. Analysis of detailed parameters of sexual activity revealed that the higher dose of MENT (100 ,ug/day) restored full ejaculatory behavior comparable with that observed in nontreated intact animals, whereas animals receiving 10 jg/day MENT exhibited longer ejaculation latencies and postejaculatory intervals that were similar to those of T acetate (200 tLg/day)-treated animals. It is significant that the lower dose of MENT acetate (5 jtg/day) was also able to stimulate ejaculatory behavior in most animals, although in a smaller proportion of tests and with longer latencies. The results demonstrate that MENT acetate was highly potent in promoting sexual behavioral activity as determined in castrated rats. We conclude that activation of male sexual behavior in rats does not require A-ring reduction of the androgen molecule.