Amounts Of Testosterone Propionate Research Articles

Testosterone implanted in the preoptic area of male Japanese quail must be aromatized to activate copulation

Intracranial implantation of minute pellets of gonadal steroids was combined with aromatase inhibitor treatment to determine if aromatization within the preoptic area (POA) is necessary for androgens to activate sexual behavior in the Japanese quail ( Coturnix japonica). In this species, implantation of pellets of testosterone propionate (TP) or estradiol benzoate (EB) in the POA of castrated males restores male-typical copulatory behavior. In Experiment 1, adult male castrated quail were implanted intracranially with 200-μg pellets of equimolar mixtures of crystalline TP +cholesterol (CHOL), TP + 1,4,6-androstatriene-3,17-dione (ATD, an aromatase inhibitor), EB + ATD, or CHOL and behavior-tested with intact males and females. Copulation was stimulated by POA implants containing TP or EB (three of six CHOL + TP males and two of seven ATD + EB males copulated vs zero of four CHOL males), but copulation was not inhibited by combining ATD with TP (three of four ATD + TP males copulated). In Experiment 2, adult male castrated quail were injected systemically with ATD or oil for 6 days prior to and 14 days after intracranial implantation of 200-μg pellets containing the same amounts of TP or EB as in Experiment 1. The ATD injections completely blocked copulatory behavior in males with TP implants in the POA such that ATD TP and Oil/TP mount frequencies differed significantly, but failed to block copulation in males with EB implants in the POA (proportions of males copulating were ATD EB , 6 8 ; ATD TP , 0 6 ; Oil/TP, 4 7 ). The cloacal foam gland, an androgen-sensitive secondary sex character, was unaffected by the dose of ATD used. We conclude that activation of copulatory behavior by TP implants in the POA is not due to nonspecific effects of high local testosterone concentrations but rather to aromatization. These redults support the hypothesis that cells within the POA aromatize testosterone to estrogens, which directly stimulate the cellular processes leading to activation of male-typical copulatory behavior.

Testicular hormones and intermale aggressive behaviour in the presence of a female rat.

A hypothesis was examined that increased levels of available testicular hormones are responsible for the increased aggressiveness of males in the presence of a female. In the first of two experiments intact male rats were injected with the androgen antagonist flutamide before exposure to oestrous, dioestrous or no females. Consistent with the hypothesis, flutamide-injected males were less aggressive than the respective control males which had been injected with oil alone. Yet the antiandrogen did not fully block the increased aggressiveness between males exposed to an oestrous female. In experiment 2 the aggressive behaviours of male rats in the presence of an oestrous female were observed after castration and restoration therapy with different amounts of testosterone propionate (TP). Neither a physiological amount (200 micrograms) nor an unusually large amount (800 micrograms) to TP could adequately mimic the effects of a gonadally intact male exposed to a sexually receptive female. These data suggest that differences in androgens available to target tissues influence aggressiveness among males exposed to a female. However, there are other factors involved, presumably the chronic morphological-physiological-behavioural changes that are provoked by copulatory experience.

Intraphypothalamic implants of testosterone or dihydrotestosterone in neonatal female rats with reference to induction of sterility.

Implants of paraffin micropellets containing about 5 microgram 5 alpha-dihydrotestosterone (DHT) into the hypothalamus of 5-day-old female rats were without effect on the sexual differentiation of the brain. By contrast, approximately the same amount of testosterone propionate (TP) given as subcutaneous or intrahypothalamic micropellets masculinized the female brain. In the light of these results as well as the author's previous findings that an antiestrogen implanted into the hypothalamus of neonatal female rats failed to block masculinization by subcutaneous injection of TP, the possibility cannot be excluded that testosterone is capable of masculinizing the brain of neonatal females without being converted into estrogens.

RECEPTIVITY SCORES OF FEMALE RATS STIMULATED EITHER MANUALLY OR BY MALES

SUMMARY Receptivity ratings of female rats that had been injected neonatally with either sesame oil or varying amounts of testosterone propionate (TP) were compared, using either a currently used manual technique or males as the test stimuli. Females receiving more than 10 μg. TP when 5 days old either rejected the male or gave minimal lordotic responses when mounted. However, they often responded with complete lordosis when manually stimulated. Untreated females in heat tended to obtain higher receptivity ratings with males than with the manual stimulus. In general, manual test ratings were found to be less related to oestrous conditions than those recorded with males. Some of the limitations and advantages of each method are discussed.

PREPUTIAL GLAND BETA-GLUCURONIDASE RESPONSE TO TESTOSTERONE AND TO TWO ANABOLIC STEROIDS.

Castration of male rats produces a reduction in preputial gland β-glucuronidase concentration to one half the very high level noted in normal rats. In such castrated rats, though both preputial gland weight and its content of β-glucuronidase are increased by administration of small amounts of testosterone propionate, the enhancement in enzyme level is noted at a lower dose level. The preputial concentration of β-glucuronidase rapidly reaches a maximum with small doses of testosterone propionate (i.e., 0.05 mg) and declines with larger doses (0.5 mg). On the other hand, the total preputial β-glucuronidase per rat reaches a maximum at the 0.1 mg level and this persists through the higher dose range. The anabolic steroids, norethandrolone and androstanazole, in a dose of 1 mg over 10 days, produce effects similar to those of testosterone on preputial β-glucuronidase. (Endocrinology 75: 273, 1964)

Testosterone Propionate Minimum for Induction of Male Development in Anurans; Comparative Data from Other Vertebrates.

SummaryAn amount of testosterone propionate as small as 1 μg/liter of aquarium water, a cancentration of 1 : 1,000,000,000, is sufficient o induce male development in a large majority of Rana sylvatica larvae raised in such a solution from hatching to metamorphosis. The relationship of these results to similar work on other vertebrates is discussed.

Biphasic Effect of Male Sex Hormone on the Pituitary of the Female Rat

It is known that testosterone and testosterone propionate are capable of suppressing the cyclic activity of the ovaries in several species of animals.1234 Because rats which were treated with these substances presented ovaries with large corpora lutea, it was suggested that the androgenic hormones caused a release of the luteinizing principle from the anterior pituitary. This, in turn, gave rise to the persistent corpora lutea as in the diestrus of pregnancy or lactation. In monkeys and humans, on the other hand, similar treatment resulted in a cessation of ovulation and some degree of ovarian atrophy. This apparent species difference in the response to testosterone was also reflected in the uterus. The uteri of rats and rabbits developed progestation-like changes,5,6 while the uteri of the primates underwent involution.3,7It seemed to us to be significant that Hertz and Meyer,8 who used 1/10 to 1/20 of the amounts of testosterone propionate which had been employed by others to induce persistent corpora l...