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PubMedDate not supplied

[Electrophoretic study of liver histones in the postnatal ontogeny of white rats: the effect of testosterone propionate and gonadectomy].

By means of polyacrylamide gel disc electrophoresis heterogeneity, electrophoretic mobility and relative content of different fractions of histones in nuclei of liver cells were studied in gonadectomized Wistar rats and in castrated in intact animals, administered with testosteone propionate. In all the experiments a significant conservatism of histone proteins was found in postnatal development. In animals, treated with the endocrine preparations, the age peculiarities were shown to reflect the quanitative proportion of different histone fractions.

Age Factors↗
PubMed1987

Treatment of pregnant rhesus macaques with testosterone propionate: observations on its fate in the fetus.

Castrated male primates, unlike castrated male rodents, respond to exogenous estrogen by releasing gonadotropin. Although this disparity is unexplained, it may occur because the amount of testicular androgen secreted during a critical period for sexual differentiation is not sufficient to completely androgenize the anlagen of the central nervous system (CNS) in male primates. Therefore, male primates might be incompletely masculinized, and if fetal males were exposed to additional androgen during sexual development, they would no longer display the positive feedback to estrogen that usually characterizes females. Besides the development of mechanisms mediating the release of gonadotropins, questions about relationships between adult male sexual behaviors and the intensity of the androgen stimulus upon developing neural structures are of interest. We tested some of these possibilities by injecting androgen into 8 pregnant rhesus macaques from Days 40 through 50 of gestation, and we compared serum levels of testosterone (T), dihydrotestosterone (DHT), and androstenedione (delta 4) in the fetal circulation with that of 5 untreated control males. Fetal sera (both male and female) from treated pregnancies did not contain significantly greater quantities of T and DHT than sera of intact control males from untreated mothers. The maternal sera, however, contained large amounts of T (125.05 +/- 27.40 [SEM] ng/ml, n = 8) and significant elevations of DHT and delta 4 after treatment. The concentrations of delta 4 in the fetal circulation were significantly elevated (p less than 0.01) in treated fetuses compared to intact control males, probably due to the actions of the 17 beta-hydroxysteroid dehydrogenases in the placenta, the fetus, or both.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Intrinsic and extrinsic influences on play fighting in rats: effects of dominance, partner's playfulness, temperament and neonatal exposure to testosterone propionate.

Play fighting is a frequent activity of juvenile rats and appears to show marked variability amongst individuals in that some rats play a great deal and others very little. This study attempted to identify some of the factors involved in producing this individual variability. The major influence over an individual's frequency of play as a juvenile was found to be the frequency of play by the partner. That is, play appears to be contagious, in that a high playing animal stimulates its partner to play frequently as well. In male juveniles, but seemingly not in female juveniles, the subsequent adult status of one partner as dominant influences the subordinate-to-be to initiate more playful contacts. In addition to these extrinsic influences, however, there appear to be intrinsic factors that influence whether an individual is a high or low playing animal. One intrinsic factor appears to be 'boldness', so that bolder animals tend to initiate more playful contacts. Higher players tend to be more susceptible to the stereotypy-inducing effects of the dopamine agonist, apomorphine, and tend to be more dependent upon the playful activity of the partner to maintain their own high levels of play. Both of these characteristics are consistent with other studies comparing bold and timid rats. Boldness, however, only seems to influence how much play a rat will exhibit, not how much play it is capable of exhibiting. Neonatal testosterone augmentation increases juvenile play fighting but not apomorphine susceptibility, suggesting that a high player need not be a bold animal. The total frequency of play an individual is capable of initiating appears to depend upon perinatal exposure to androgens. Boldness and the playfulness of the partner appear to modulate the expression of this hormonally set value.

Agonistic Behavior↗
PubMed1994

[Comparison between the influence of estradiol benzoate, testosterone propionate and human chorionic gonadotropin on initiation of spermatogenesis in the rat].

Newborn male rats were injected daily from the 5th to 15th day of life with: EB in doses of 6.2 or 12.5 or 25.0 micrograms and TP in doses of 1.2 or 2.5 or 5.0 mg (experiment 1), and with hCG (experiment 2) in doses of 2.0 or 4.0 or 8.0 I.U. Animals were sacrificed on the 16th day of life, testes and seminal vesicles were taken and fixed. The function of seminiferous tubules was examined by quantitative analysis of spermatogenesis. EB increased the mean number of germinal cells. TP stimulated differentiation of spermatogonia, but it decreased the number of all germinal cell types. Only the lowest dose of hCG stimulated the mean number of germ cells in the earliest stages of spermatogenesis, hCG used in the higher doses suppresses maturation of seminal tubules and decreases testicular weight.

Animals↗