Evidence for a morphological sex difference within the medial preoptic area of the rat brain.

Ovarian steroids affect the food intake and body weight of rats. These effects are probably mediated by estradiol and progesterone, since these 2 hormones are more effective than their principal metabolites (estrone and 5alpha-pregnane-3,20-dione, respectively) in altering the food intake and body weight of ovariectomized rats. Estradiol seems to affect food intake by lowering the set point about which body weight is regulated in a dose-dependent fashion. These actions of estradiol can be attenuated or completely blocked by concurrent injections of progesterone. Estradiol-treated ovariectomized rats are far more responsive to the weight- and appetite-promoting actions of progesterone than are ovariectomized-adrenalectomized rats, suggesting that the principal action of progesterone on energy balance may be to interfere with the effects of estradiol.

Some effects of ovarian hormones on food intake and body weight in female rats.

Castrated male rats injected daily with 2 micrograms of estradiol benzoate (EB) combined with 200 micrograms of dihydrotestosterone propionate (DHTP) displayed masculine mating behavior which was indistinguishable from that of other castrates treated with 200 micrograms of testosterone propionate (TP). Significantly less copulation was seen in rats treated with either 4 micrograms of TP plus 200 micrograms of DHTP or 2 micrograms of EB. Mating in male rats may depend on the action of both estrogenic and 5alpha-dihydro metabolites of testosterone.

http://science.sciencemag.org/content/sci/182/4109/283.full.pdf

Copulation in Castrated Male Rats following Combined Treatment with Estradiol and Dihydrotestosterone

Aromatase activity in the rat brain: Hormonal regulation and sex differences

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

Free and propionate forms of dihydrotestosterone were compared with testosterone propionate to evaluate their ability to restore masculine behavior in castrated rats. Induction of the growth of penile "spines" in castrated adult rats by testosterone propionate and dihydrotestosterone propionate was examined. Testosterone propionate was the only steroid which restored the ejaculatory pattern to castrated males. All of the hormones induced the growth of penile "spines". Therefore the failure of dihydrotestosterone propionate or dihydrotestosterone to restore masculine behavior to castrated males was probably not due to an inadequate action of these hormones on the penis. All hormones caused significant gains in body weight with testosterone propionate causing the highest gain. Testosterone propionate and dihydrotestosterone propionate caused a significant decrease in testicular weight in immature rats. Testosterone propionate caused a considerable increase in seminal vesicle weight much larger than that induce by dihydrotestosterone propionate. Human chorionic gonadotropin (HCG) treatment seemed to stimulate release of testosterone from the testes of immature animals.

THE COMPARATIVE ACTIONS OF TESTOSTERONE PROPIONATE AND 5α-ANDROSTAN17β-OL-3-ONE PROPIONATE ON THE REPRODUCTIVE BEHAVIOUR, PHYSIOLOGY AND MORPHOLOGY OF MALE RATS

H. H. Feder

Papers

THE COMPARATIVE ACTIONS OF TESTOSTERONE PROPIONATE AND 5α-ANDROSTAN17β-OL-3-ONE PROPIONATE ON THE REPRODUCTIVE BEHAVIOUR, PHYSIOLOGY AND MORPHOLOGY OF MALE RATS