Problems associated with dose response in steroid-hormone activation of structural genes

The neonatal cerebellum: the highest level of glucocorticoid receptors in the brain

We investigated the postnatal development of glucocorticoid receptors (GR) in rat cerebral cortex, hippocampus, olfactory bulbs and cerebellum during a period when cell proliferation, including neurogenesis in the latter 3 brain parts, is intensive. The concentration of GR was determined as the specific binding of [3H]dexamethasone to the cytosol stabilized against the inactivation of unoccupied receptor molecules by sodium molybdate. Unoccupied GR levels were found to increase during the first week, most rapidly in the cerebellum, where it reached the maximum during the second week. Specific binding of [3H]dexamethasone to the cerebellar nuclear fraction has already been present at days 8 and 15. By the end of the second week the cytosolic unoccupied GR begin to decline in the cerebellum. Total receptor binding, however, estimated in adrenalectomized animals does not decline. On the other hand, at day 8 adrenalectomy did not reveal more receptors than obtained in intact animals. Large numbers of GR in the neonatal cerebellum may specifically mediate the adverse effects of glucocorticoids on the cerebellar development during the period when the intensive morphogenetic processes take place in this part of the brain.

Are fluorescein-conjugated androgens appropriate for a histochemical detection of prostatic androgen receptors?

Histochemical fluorescence techniques could be of great value in order to assay androgen receptors (AR), particularly in punch biopsies from human prostatic carcinoma (PCA). Therefore, prostatic tissue was examined for specific binding of fluorescein-labeled 5 alpha-dihydrotestosterone derivatives (FDHT) to AR. Using a 17 beta-fluoresceinated DHT derivative (17-FDHT), variable fluorescence was found in human and rat prostates at high 17-FDHT concentrations. This fluorescence could be blocked by unlabeled DHT in 11 and 73% of human and rat prostatic tissue, respectively. Control studies of receptor and organ specificity were conducted and showed that preheated slices from rat prostates displayed no decrease of fluorescent staining. No difference in fluorescence intensity could be seen between prostates from castrated and uncastrated rats. Unstained tissue slices frequently showed a considerable intensity of autofluorescence. An appreciable amount of fluorescence in both rat liver and spleen was found. From these results and various general methodical problems inherent in fluorescent receptor assays, we conclude that the fluorescence techniques described are inappropriate for demonstration of AR.

Localization of 3H-estradiol in the reproductive organs of male and female baboons

The uptake and retention of radiolabeled estradiol by both the male and female reproductive organs were examined in the baboon. Two male and two female baboons were injected intracardially with 1 microgram/kg body weight of 3H-estradiol and two animals, one male and one female, were injected with both labeled and 100 micrograms/kg body weight of unlabeled estradiol. One and a half hours after the injections, the animals were sacrificed and the uterus, cervix, vagina, oviduct, seminal vesicles, and prostate gland were removed and processed for autoradiography. The stratified squamous epithelia of the cervix and vagina demonstrated a light uptake of the label in the germinative, but not in the superficial cell layers. The columnar cells lining the oviduct and uterine glands were labeled, whereas the luminal epithelium of the uterus and the glandular epithelia of the seminal vesicles and prostate gland did not sequester the tritiated steroid. The interstitial cells of all the organs studied demonstrated a moderate to heavy uptake of the radioactivity, whereas the smooth muscle cells were lightly labeled except in the vagina, in which these cells displayed a moderate number of silver grains.