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Gap junctions are membrane specializations that are composed of connexin protein. The assembly of these proteins into channels between cells allows for the intercellular transfer of regulatory molecules. In the adrenal gland, as in most other tissues, intercellular communication provides the potential for regulation of a number of complex interactive cell processes including differentiation, steroidogenesis, migration, and proliferation. This review is concerned with the regulation of gap junctions and cell function in cortical cells of the adrenal gland and in pathological disorders such as adrenal cancer.

Electrolytic lesions of the hypothalamic medial forebrain bundle (MFB) produced substantial deficits in the copulatory behavior of male rats, but no changes in testicular, seminal vesicle, ventral prostate or penis weights. Radioimmunoassay of serum from lesioned and control animals revealed a small but statistically insignificant reduction in testosterone and LH levels, and no change in FSH levels of lesioned males. In a second experiment, androgen levels were maintained in castrated males by subcutaneous implants of silastic capsules containing crystalline testosterone; this procedure failed to prevent the copulatory deficit which accompanied subsequent MFB lesions. We have concluded that the behavioral deficit produced by such lesions is not a direct result of pituitary-gonadal dysfunction.

Considerable evidence has accumulated to suggest that ethanol is a gonadal toxin. With this emphasis the role(s) that liver disease and malnutrition might play have been neglected. The following studies were performed to either confirm the primacy of alcohol as a gonadal toxin or to point out the respective roles of these latter two conditions. Five groups of animals were studied: an ad libitum-fed control, carbon tetrachloride-treated (cirrhosis control), weight-restricted (malnutrition control), a pair-fed control, and an ethanol-fed group. The liver function and histology of all but the ethanol-fed and carbon tetrachloride cirrhosis controls were normal. In contrast, only the testicular weight and histology of the alcohol-fed animals were abnormal. Testosterone levels were reduced only in the ethanol-fed group ( P P P P

Mature female Wistar rats were ovariectomized and injected daily for 15 days with sesame oil, or with 100, 500 or 1000 M-g testoster- one (T) or dihydrotestosterone (DHT). LH was assayed by radioimmunoassay in serum collected 24 hr after the last injection. Daily administration of 100 ng DHT completely suppressed the post- ovariectomy increase in serum LH, while the same amount of T only slightly inhibited this response. At larger dosages both androgens were effective in inhibiting LH secretion. Bilateral implantation of either T or DHT into the hypothalamus (pre- mammillary arcuate area and mammillary nuclei) immediately after ovariectomy failed to prevent the postovariectomy rise in serum LH. The re- sults suggest but do not prove that reduction of T to DHT mav be involved in the inhibition of LH by T. (Endocrinology 91 : 1372, 1972) R ECENTLY, it has been shown that several of the effects produced by testosterone (T) administration may be due, in part, to its con- version to dihydrotestosterone (DHT) (1,2). A Sa-reductase enzyme which converts T to DHT is present not only in the accessory sex organs of the male rat (prostate, seminal vesi- cles, etc.), but also in the hypothalamus and pituitary gland (3,4). However, the functional role of this enzyme system in the hypothalamic- pituitary complex is not known. It is well estab- lished that T administration inhibits the release of LH and FSH in both male and female mam- mals (5-7). The effect of DHT on gonadotro- pin secretion has been less often studied. DHT has been found to block ovarian compensatory hypertrophy in the female rat (8,9), and to reduce serum LH and FSH levels in castrated male rats (10). In contrast, Faiman and Winter (11) and Jaffe and Perez-Palacios (unpublished data) failed to reduce LH and FSH levels in castrated patients with testicular feminization by injecting DHT propionate. However such patients are also not responsive to treatment with testosterone (12). In the present study the effects of both T and DHT on serum LH levels of ovariectomized rats were compared. Moreover, in an attempt to lo- calize the site of action of these androgens, we investigated the effects of hypothalamic im

Intact mature female rats were injected once daily for 15 days with sesame oil, or with 100, 500 or 1,000 µg testosterone (T) or dihydrotestosterone (DHT). Both androgens, at 500 µg and 1,000 µg doses, produced ovarian atrophy. DHT was more effective in inducing anestrus, as well as uterine and vaginal atrophy. Mean diameters of all follicles with antra were reduced by DHT at 500 and 1,000 µg dose levels. In contrast, T did not suppress follicular growth, but actually, at the low dose (100 µg), significantly stimulated it. In a second series of experiments, in which the same treatments were given to ovariectomized rats, serum FSH was measured by radioimmunoassay 24 hr after the last injection. The low (100 µg) dose of DHT reduced serum FSH more markedly than the low dose of T did. At higher dose levels, both steroids reduced FSH serum levels to indistinguishably low values. These findings suggest that, in female rats, DHT suppresses FSH release more effectively than T. (Endocrinology 95: 722, 1974)

Intra-arterial injections (8–75 mg/kg) of L-3,4, dihydroxyphenylalanine (L-dopa) at 1 p.m. on the afternoon of proestrus produced a rapid increase in serum LH in unanesthetized female rats. Maximum re