Actions of esters of testosterone, dihydrotestosterone, or estradiol on sexual behavior in castrated male guinea pigs

Prepuberally castrated male guinea pigs were treated in adulthood with estradiol benzoate, testosterone propionate, dihydrotestosterone propionate or corn oil (vehicle control). Both corn oil and estradiol benzoate were ineffective in augmenting or inducing any aspect of adult male sexual behavior. Dihydrotestosterone propionate and testosterone propionate were both effective in establishing the complete male sexual behavior pattern, although they differed in the manner in which they affected specific components. For example, males treated with testosterone propionate showed more non-intromissive but not more intromissive mounts than males treated with dihydrotestosterone propionate. In addition, the average frequency of thrusts per intromission was greater for males treated with dihydrotestosterone propionate than for males treated with testosterone propionate.     

Inhibition of lordosis in female rats by subcutaneous implants of testosterone, androstenedione or dihydrotestosterone in infancy

Female rats were implanted on the day of birth with Silastic capsules containing nonesterified testosterone, androstenedione, or dihydrotestosterone. The date of vaginal opening was assessed until sacrifice. The animals were ovariectomized, treated with estradiol benzoate and progesterone, and tested for the display of lordosis. The animals were then administered testosterone propionate and the size of the phallus was taken. Testosterone and dihydrotestosterone completely inhibited vaginal opening; androstenedione was partially effective. Testosterone almost completely inhibited lordosis behavior; androstenedione was partially effective and dihydrotestosterone was ineffective. All three androgens facilitated phallic development.     

The effectiveness of steers and heifers treated with oestrogen or testosterone to detect oestrus in cattle

Two experiments were carried out to determine the effectiveness of steers and heifers, treated with oestrogen or testosterone, in the detection of oestrus in cattle.In the first experiment 17 steers castrated at birth and 16 castrated at 6 months of age were randomly allocated to three groups and received an 800 mg subcutaneous implant of testosterone, subcutaneous injections of 10 mg oestradiol benzoate per week for 16 weeks or no hormone (controls). In addition, six heifers were injected subcutaneously with 10 mg oestradiol benzoate per week for 16 weeks while six untreated heifers served as controls. Animals were observed in a standardised libido test 2, 4, 8, 16, 20 and 24 weeks after treatment commenced. The time to first mount and the number of mounts per animal responding in the presence of oestrous heifers were recorded. Both steers and heifers treated with oestradiol benzoate were superior at detection of oestrus in cattle than animals treated with testosterone or those receiving no hormone. Oestrogen-treated animals generally detected heifers in oestrus in less than 3 min after introduction and mounted these animals between 20 and 30 times in one hour. This response was consistent throughout the duration of the experiment. There was no effect of age at castration of steers on development of male behaviour.The second experiment determined the rate and degree of development of male behaviour in steers in response to weekly subcutaneous injections of 0, 2, 4, 8 or 16 mg oestradiol benzoate per 250 kg body weight, 250 mg testosterone or 150 mg dihydrotestosterone for a period of 15 weeks. Steers treated with oestradiol benzoate again proved to be more successful than untreated or testosterone-treated steers at consistently detecting and mounting oestrous heifers. The best response was obtained from steers treated with 8 mg/250 kg body weight per week. The practical application of this work is discussed.     

The content of five sex steroids in human testis

In order to assess whether intratesticular hormone content may be helpful for prediction of successful conception in men with fertility problems, five sex steroids, testosterone, dihydrotestosterone, androstenedione, estradiol and, for the first time epitestosterone, were measured in testicular tissue obtained by surgical retrieval from total 84 men. The group consisted of non-obstructive azoospermic men, aged 21-67 years who attended the centre for in vitro fertilization. Steroids after ether extraction and solvent partition were separated by high performance liquid chromatography and then measured by specific radioimmunoassays. The values varied considerably with means ± S.D. 2.43±2.47, 0.27±0.24, 0.080±0.13, 0.071±0.089 and 0.31±0.27 for testosterone, dihydrotestosterone, androstenedione, estradiol and epitestosterone, respectively.     

Testosterone,androstenedione and dihydrotestosterone: Effects on mating behavior of male rats

The relative effectiveness of testosterone, androstenedione, and dihydrotestosterone in maintaining mating behavior following castration of male rats was studied. In Experiment 1 testosterone, but not dihydrotestosterone, was found to maintain mating. In Experiment 2 testosterone and androstenedione were found to be equally effective in maintaining mating. Dihydrotestosterone failed to maintain mating and was no more effective than no treatment at all. Testosterone, androstenedione, and dihydrotestosterone significantly enhanced seminal vesicle and penis weight. In Experiment 3 castrated male rats were administered radiolabeled testosterone, androstenedione, or dihydrotestosterone. Radioactivity was found in hypothalamic and seminal vesicle samples indicating that these steroids can be accumulated by brain as well as peripheral androgen-sensitive tissues. It was concluded that the peripherally active steroid dihydrotestosterone probably plays no role in the maintenance of sexual behavior.     

Diurnal patterns of testosterone, dihydrotestosterone, estradiol, and cortisol in serum of rhesus males: Relationship to sexual behavior in aging males

This study was carried out to determine differences between old and young rhesus males in levels and diurnal patterns of testosterone, dihydrotestosterone, cortisol, and estradiol, and to determine correlations between these hormones and sexual behavior of the old males. Blood was drawn from old (n = 9) and young (n = 9) rhesus males over 5 consecutive days at 0900, 1300, and 2100 hr. The two groups of males did not differ in mean serum levels of testosterone, dihydrotestosterone, or estradiol at any time. Although the old and young did not differ in cortisol levels at 0900 and 1300 hr, the cortisol levels at 2100 hr were lower in the old males. Diurnal variations in testosterone, dihydrotestosterone, and cortisol were comparable in old and young males. Mean serum levels of estradiol were significantly higher at 0900 hr than at 1300 hr in the old males, whereas in the young males estradiol levels did not differ with time of day. There was a significant positive correlation between testosterone and yawning rate, and cortisol levels were correlated positively with rate of contacting, rate of mounting, and percentage of tests with erections. The decline in sexual performance of old rhesus males cannot be attributed to changes in the levels or diurnal patterns of testosterone, dihydrotestosterone, or estradiol, but lower cortisol levels in old males may contribute to the decline in sexual behavior.     

Measurement of steroid sex hormones in serum: a comparison of radioimmunoassay and mass spectrometry

Concern has been raised about the adequacy of radioimmunoassays to measure steroid sex hormones in population studies. We compared steroid sex hormone measurements in serum by radioimmunoassay with mass spectrometry. Four male and four female serum pools with known relative concentrations of steroid sex hormones were measured multiple times by both methods. Because measurements are expected to increase linearly with concentration for each sex, we examined whether the linear regressions of hormone measurements on concentration were the same for radioimmunoassay and mass spectrometry. Estradiol, estrone, androstenedione, testosterone, and dehydroepiandrosterone sulfate were measured in female pools; testosterone, dihydrotestosterone, androstenedione, and dehydroepiandrosterone sulfate were measured in male pools. Regression slopes for radioimmunoassay and mass spectrometry measurements were comparable for all hormones except androstenedione, which had a steeper slope when measured by mass spectrometry (P < or = 0.02). Intercepts for radioimmunoassay and mass spectrometry were similar and close to zero for estradiol, androstenedione, dehydroepiandrosterone sulfate, and in male samples, testosterone. For testosterone in female samples, estrone, and dihydrotestosterone, radioimmunoassay and mass spectrometry intercepts differed significantly. Standard deviations of individual measurements by radioimmunoassay and mass spectrometry differed by hormone and serum concentration; neither method consistently measured hormone concentrations with less variability. Our findings suggest that although absolute concentrations may differ for some hormones, radioimmunoassay and mass spectrometry can yield similar estimates of between subject differences in serum concentrations of most steroid sex hormones commonly measured in population studies. Relative power of studies using radioimmunoassay and mass spectrometry will depend on the hormones measured and their serum concentrations.     

Effect of steroid implants on sexual behavior of beef calves

The sexual behavior of 53 beef heifers and 66 beef steers was observed and recorded for 7 days following insertion of subcutaneous ear implants at 2 months of age. Thirty-five of the heifers were implanted with Synovex S (200 mg of progesterone and 20 mg of estradiol benzoate). Forty-four of the steers were implanted with Synovex H (200 mg of testosterone and 20 mg of estradiol benzoate). The remaining 18 heifers and 22 steers served as nonimplanted controls. Synovex S treatment increased the incidence of mounting (P < 0.005) and mounting receptivity (P < 0.005) of heifers, while Synovex H treatment had only slight effect, if any, on the mounting behavior (P < 0.25) and mounting receptivity (P < 0.25) of steers. Both steers and heifers mounted heifers more frequently than steers (P < 0.005). Heifers were mounted with similar frequencies by both heifers and steers (P < 0.90), while steers were mounted only by heifers (P < 0.15).     

A comparison of the estrous behavior of Holstein-Friesian cows when cubicle-housed and at pasture

This study compared estrous behavior of dairy cows kept in cubicle housing and fed a total mixed ration diet (HOUSED treatment) with that of cows kept at pasture with concentrate supplementation (PASTURE treatment). Behavior was compared both in the 48 h around standing estrus and during the standing estrus period. The 23 spring-calving Holstein-Friesians in each treatment were observed directly three times per day for nine weeks. The occurrence of nine selected behaviors associated with estrus was recorded during 20 min observation sessions. Twelve standing estrus events from each treatment were selected for analysis of the frequency of these nine behaviours over the 48 h around standing estrus. Milk progesterone profiles were used to confirm the dates of standing estrus events. Attempting to mount other cows, sniffing the anogenital region of other cows, resting the chin on other cows, receiving chin rests and head-to-head butts all showed significant changes in frequency in the 48 h around standing estrus in both treatments, reaching a peak during standing estrus (P ≤ 0.05). Mounting other cows increased significantly in the PASTURE treatment around standing estrus (P < 0.001), but not in the HOUSED treatment. The frequency of ano-genital sniffs received by the animals in the PASTURE treatment also increased significantly around standing estrus (P < 0.01) but not in the HOUSED treatment. When the animals were in standing estrus there was a significantly higher frequency of standing to be mounted in PASTURE than in HOUSED cows (median (q1, q3) PASTURE = 2.5 (1.0, 3.0), HOUSED = 0.0 (0.0, 1.0)) (P < 0.01), but no difference in the frequency of the other eight sexual behaviors recorded. HOUSED cows did not exhibit the same increase in mounting during the standing estrus period as PASTURE cows and received fewer mounts in observation sessions during standing estrus. These results have implications for the use of estrus detection systems that rely solely on mounting behavior in cubicle-housed dairy cows.     

Steroid metabolism by germ cells and spermatozoa in men after vasoepididymostomy.

The ability of germ cells (spermatocytes and spermatids) and spermatozoa present in human ejaculate to metabolize steroids was studied in men with obstructive infertility who had undergone vasoepididymostomy as corrective surgery. Steroid metabolism by spermatozoa in men who had undergone vasovasostomy was also investigated. Germ cells converted testosterone mainly to androstenedione. In addition to androstenedione, dihydrotestosterone and androstanediols were also formed in incubations using spermatids. Both types of germ cells converted estradiol to estrone. Spermatozoa from subjects who had undergone vasoepididymostomy or vasovasostomy converted testosterone to androstenedione as in normal men, while spermatozoa from infertile subjects converted testosterone mainly to dihydrotestosterone. Seminal fluid, free of germ cells, did not show steroid-metabolizing capability.     

Estradiol-17 beta and androgen secretion by isolated porcine ovarian follicular cells in vitro

The cellular sources and gonadotropic regulation of porcine ovarian estrogen and androgen were assessed by culturing isolated granulosa cells and thecal cells from medium size follicles (4-6 mm diameter) separately for 24 h in a chemically defined medium containing gonadotropins and (or) testosterone. At the end of the culture period, estradiol-17 beta (estradiol) and androgens in the media were determined by radioimmunoassays. Production of estradiol by granulosa cells without an exogenous aromatizable androgen was low in the absence or presence of a highly purified preparation of either follicle-stimulating hormone (FSH. 0.25 microgram/mL) or luteinizing hormone (LH. 1 microgram/mL). Addition of testosterone or androstenedione (0.5 microM), but not dihydrotestosterone or pregnenolone, significantly increased estradiol secretion. Additional increases were observed when FSH, LH, prostaglandin E2, or dibutyryl cyclic 3'.5'-adenosine monophosphate was present. Production of estradiol by thecal cells was low in the presence or absence of exogenous testosterone, and was essentially unaffected by the presence of gonadotropins. Thecal cells, however, released large amounts of androstenedione and smaller amounts of testosterone and other androgens during 24-h culture and the production of these androgens was stimulated by LH but not by FSH. Androgen secretion by granulosa cells was negligible when compared with the theca and was unaffected by gonadotropins. It is concluded that the theca is the prime site for follicular androgen biosynthesis by the porcine ovarian follicle, and, upon LH stimulation, may provide androgen precursors for estradiol production by granulosa cells.     

Sexual behavior of male golden hamsters receiving diverse androgen treatments

Four androgens were compared for their effectiveness in maintaining the sexual behavior of castrated male golden hamsters. Sexually experienced males were divided into 4 experimental treatment groups which received 500 μg daily of testosterone, androstenedione, dihydrotestosterone or androsterone. Control castrates were given oil. All animals were tested for sexual behavior every 2 wk for 10 wk following the onset of experimental treatment. Testosterone and androstenedione were the only androgens that maintained intromissions above the oil control level. However, testosterone, androstenedione and androsterone, but not dihydrotestosterone were effective in maintaining mounting behavior above the oil control level. No differences were detected between these 4 androgens in their maintenance of penile papillae.     

Effects of dihydrotestosterone and estradiol benzoate pretreatment upon testosterone-induced sexual behavior in the castrated male rat

Three groups of inexperienced castrated male rats were treated daily for 15 days with oil, estradiol benzoate (1 μg), or dihydrotestosterone (1 mg), and thereafter injected daily with testosterone (1 mg) for 21 days. Sexual behavior was tested every third day after the start of the pretreatment until day 36. Estradiol benzoate or dihydrotestosterone failed to elicit sexual behavior. Pretreatment with dihydrotestosterone, but not estradiol benzoate, significantly shortened the intervals to initiation of mounting and intromission in response to testosterone. The results suggest that fully developed genitals (penis and/or sexual accessories) facilitate initiation of copulatory behavior in response to testosterone administration.     

Effect of cyanoketone on follicle-stimulating hormone (FSH) induction of receptors for FSH in granulosa cells of the rat

Follicle-stimulating hormone (FSH) enhances the conversion of testosterone or androstenedione into estradiol by stimulating the aromatase enzyme system. Estradiol also enhances FSH action. Thus, a synergistic action of FSH and estradiol may be required for maturation of ovarian follicles. We hypothesized that estradiol may be required for FSH action. Thus, blocking estrogen synthesis should prevent FSH-induced increases in FSH receptors. Hypophysectomized rats were divided into five groups and injected subcutaneously with: 1) saline, 2) cyanoketone (0.05 mg, blocks the conversion of pregnenolone to progesterone), 3) ovine FSH (oFSH, 200 micrograms), 4) cyanoketone then oFSH 24 h later, or 5) cyanoketone plus estradiol [or progesterone, testosterone, promegestrone (R5020), dihydrotestosterone (DHT), 2 mg], then FSH 24 h later. Animals were decapitated at 0, 12 or 24 h after an injection of oFSH, and membrane receptors for FSH and luteinizing hormone (LH), plus nuclear receptors for estradiol from granulosa cells, were measured. LH receptor levels were increased only after administration of FSH and estradiol. At 0 and 24 h, numbers of FSH or estradiol receptors were similar in saline- and cyanoketone-treated animals. FSH alone increased (P less than 0.01) FSH and estradiol receptors 3-fold and 4-fold, respectively, over controls by 12 and 24 h. Cyanoketone prevented these increases in FSH and estradiol receptors. Estradiol replacement fully reversed the effects of cyanoketone on FSH action. Replacement with progesterone and testosterone was able to only partially restore levels of FSH receptors; however, estradiol receptor numbers were also increased.(ABSTRACT TRUNCATED AT 250 WORDS)     

Brain and plasma levels of testosterone, dihydrotestosterone and estradiol in the one-day-old rat.

Current evidence indicates that the secretion of testosterone during perinatal life is essential in organizing the male brain which subsequently directs the male pattern of gonadotrophin (GTH) secretion and adult male sexual behavior in the rat. It has been hypothesized that testosterone is converted into estradiol enzymatically in the brain prior to its action. In the absence of testosterone and with the resultant low levels of estradiol, female patterns of gonadotrophin secretion and behavior result. In order to investigate this hypothesis further, the endogenous levels of gonadal steroids in the plasmas and brains of 24–48 hr old male and female rats were determined. Pooled samples were analyzed for testosterone, dihydrotestosterone and estradiol by radioimmunoassay. Testosterone levels in male brain and plasma samples were significantly (10-fold) higher than those in the female brain and plasma samples. Brain levels of estradiol were significantly higher in the male than in the female neonate, while plasma levels were identical. Whether the higher level of estradiol in the male brain is due to enzymatic conversion from testosterone within the brain differences in permeability or some other mechanism cannot be stated at this point. The significantly higher brain levels of both testosterone and estradiol in male neonates do fit the pattern predicted by the present concept of sexual differentiation. Dihydrotestosterone levels in brain and plasma of male rats were about 25% of those of testosterone. However in females the brain levels of dihydrotestosterone were significantly higher than testosterone even though the plasma levels of these hormones were identical. This may reflect a protective mechanism through which permeability of testosterone is lowered in the neonatal female brain during the critical period or simply a functional conversion of testosterone to dihydrotestosterone in the female during this period.     

Mounting and receptive behavior in the ovariectomized female rat: Influence of estradiol,dihydrotestosterone, and genital anesthetization

Two experiments were performed with ovariectomized female rats in an attempt to determine whether estradiol and dihydrotestosterone work synergistically in the brain to activate mounting behavior. In Expt 1, performed in Göteborg, it was found that females treated daily with 2 μg estradiol benzoate (EB) combined with 500 μg dihydrotestosterone (DHT) displayed significantly more mounts with pelvic thrusting than other females treated with the oil vehicle, 500 μg DHT, or 2 μg EB. The behavior of rats receiving EB + DHT was indistinguishable from that of yet another group of females which received 200 μg testosterone propionate (TP). In Expt 2, performed in Rotterdam, it was found that ovariectomized female rats treated with either 200 μg TP or 2 μg EB + 200 μg dihydrotestosterone propionate (DHTP) mounted significantly more than females treated with 2 μg EB. Both clitoral size and the growth of cornified papillae on the glans clitoris were stimulated by the administration of TP or EB + DHTP. However, in no group was the frequency of mounting affected by anesthetization of the clitoris and external vagina with lidocaine paste. Lordosis quotients of females treated with EB + DHTP were significantly lower than in rats receiving either EB or TP, again regardless of whether or not the genital region was anesthetized. It is concluded that the effects of DHT on estradiol-induced mounting and receptivity most likely result from the action of this androgen on the brain, and not from the stimulatory effect which DHT may exert on genital sensory receptors.     

Intratesticular steroid levels and their hormonal control

Litter-mate adult male rats were treated with daily intramuscular injections of ACTH (10.5 micrograms), dexamethasone (2.0 mg), ethynyl estradiol (1.7 micrograms) and hCG (5 IU) for three consecutive days. The animals were sacrificed on the fourth day and the intratesticular and peripheral plasma steroid levels were analyzed. The steroids measured by radioimmunoassay included pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone, progesterone, 17-hydroxyprogesterone, androstenedione, testosterone and dihydrotestosterone. In addition, the sulphoconjugated forms of pregnenolone, dehydroepiandrosterone, testosterone and dihydrotestosterone were estimated in the peripheral blood. The administration of ACTH diminished the intratesticular levels of all steroids studied. Also dexamethasone and ethynyl estradiol treatment suppressed all intratesticular steroid levels, except that of pregnenolone (the former) and of 17-hydroxyprogesterone (the latter). The suppressive effect of ethynyl estradiol was strongest on the levels of the delta 5-steroids and that of dexamethasone on the delta 4-steroids; the latter was significantly stronger than the effect of ACTH. The stimulatory effect of hCG was limited to the metabolism of progesterone and was restricted to the sequence: 17-hydroxyprogesterone----androstenedione----testosterone---- dihydrotestosterone. Dexamethasone-suppression, and hCG-stimulation of the intratesticular levels of delta 4-steroids, was mirrored by corresponding changes in the peripheral plasma levels, with the exception of the plasma levels of androstenedione which were not influenced by any of the treatments studied. Also the suppression of intratesticular testosterone and dihydrotestosterone levels by ACTH, dexamethasone, or ethynyl estradiol was closely reflected by their plasma levels both in the unconjugated and sulphoconjugated forms. On the hand, the administration of ACTH diminished the intratesticular levels of pregnenolone and progesterone but significantly increased those in the plasma. Moreover, both ACTH and ethynyl estradiol reduced the levels of all delta 5-steroids in testicular tissue, but not in the peripheral plasma, although they decreased the circulating levels of pregnenolone sulphate and dehydroepiandrosterone sulphate. The data are interpreted as suggesting that the hormonal agents studied interfere with testicular steroidogenesis through different mechanisms.     

Male sexual behavior in deer mice (Peromyscus maniculatus) following castration and hormone replacement

Sexually experienced male deer mice (Peromyscus maniculatus bairdi) were castrated and tested for male sexual behavior. In the weeks following castration male sexual behavior decreased. Ejaculation disappeared first, followed by intromission and, finally, mounting. Castrated males failing to copulate were assigned to one of four treatment groups: 200 μg testosterone propionate (TP); 200 μg dihydrotestosterone propionate (DHTP); 2 μg estradiol benzoate (EB); or sesame oil (OIL). TP and DHTP were equally effective in restoring the complete male sexual behavior pattern. In contrast, EB was effective in stimulating mounting and minimally effective in stimulating intromissions (vaginal penetration), but did not stimulate ejaculatory responses. These data indicate that in deer mice testosterone may mediate male sexual behavior through reduction to dihydrotestosterone rather than through aromatization to estradiol.     

The effect of neonatal estrogen treatment on plasma hormone levels and behaviour in pre- and post-pubertal bulls

Plasma testosterone, androstenedione and LH concentrations were measured at regular intervals from birth to 500 days of age in bulls; bulls treated with estradiol for 3 weeks after birth; steers and heifers. Behavioural observations were conducted at various periods over 12 months. Apart from a possible quietening effect at 4 months of age, neonatal estrogen administration had no effect on the aggressive behaviour of young bulls. There were no differences among the groups in testosterone levels for the first 60 days but by day 100 the levels in the normal and estrogenized bulls had risen significantly. No differences in androstenedione concentration occurred among the groups. Plasma LH decreased for the first 7 days in the bulls, steers and heifers then rose gradually, however a marked rise occurred in the steers from day 28. The neonatal decline in plasma LH was extended during the period of estrogen administration.     

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.