Michael G. Mawhinney

Daily transdermal administration of selegiline to guinea-pigs preferentially inhibits monoamine oxidase activity in brain when compared with intestinal and hepatic tissues

Selegiline has been formulated in an acrylic polymer adhesive mixture to be employed as a constant release topical patch for daily transdermal administration. Application of this selegiline transdermal system (STS) to guinea‐pigs resulted in an average delivery of 1.185 mg selegiline/cm2 patch/24 h. STS dose‐response curves were generated by altering patch size (cm2). A transdermal dose range was identified which inhibited guinea‐pig brain monoamine oxidase‐B (MAO‐B) by greater than 95 % yet provided for a dose‐dependent inhibition of monoamine oxidase‐A (MAO‐A) activity. The ID50 for inhibition of MAO‐A activity in response to a 21‐day daily regimen with transdermal selegiline was approximately 7.5‐fold lower for cortical and striatal brain regions compared with that obtained for duodenum; hepatic MAO‐A was unaffected following the same dosing regimen. By contrast, orally administered selegiline inhibited brain and duodenal MAO‐A to the same extent, and generated a shallower dose–inhibition curve for brain MAO‐A inhibition. In addition, transdermal delivery was approximately 6–8‐times more potent than oral selegiline for the inhibition of brain MAO‐A activity. It is concluded that daily transdermal selegiline administration may provide therapeutic advantages over oral treatment, based on its preferential, dose‐dependent inhibition of brain vs peripheral MAO‐A activity.

Effects of DDT on radioactive uptake from testosterone-1,2-3H by mouse prostate glands☆

Orally administered technical grade DDT (12.5,25 or 50 mg/kg) was studied in intact male mice and in intact and ovariectomized female mice. Regardless of the dose of DDT, there was a significant reduction (P < 0.05%) in the prostate glands ability to assimilate radioactive testosterone. The mechanism(s) of inhibitory action of DDT upon male sex accessory glands did not appear to be due to its reported inherent estrogenicity. Single po doses of DDT-3H revealed considerable amounts of radioactivity localized in several male reproductive organs. The prostate and the testes exhibited significant amounts as early as 1 and 2 hr post-administration. Epididymal fat pads retained amounts of radioactive pesticide as long as 12 days after DDT-3H ingestion.

Endocrinology of sex steroid hormones and cell dynamics in the periodontium

Numerous scientific studies assert the existence of hormone-sensitive periodontal tissues. Tissue specificity of hormone localization, identification of hormone receptors and the metabolism of hormones are evidence that periodontal tissues are targets for sex steroid hormones. Although the etiologies of periodontal endocrinopathies are diverse, periodontal pathologies are primarily the consequence of the actions and interactions of sex steroid hormones on specific cells found in the periodontium. This review provides a broad overview of steroid hormone physiology, evidence for the periodontium being a target tissue for sex steroid hormones and theories regarding the roles of sex steroid hormones in periodontal pathogenesis. Using this information, a teleological argument for the actions of steroid hormones in the periodontium is assessed.

Localization, metabolism, and binding of estrogens in the male rat.

Abstract Estrogen assimilation by male Wistar rats was examined in these studies in several accessory sex organs (seminal vesicles and anterior, dorsal, lateral, and ventral prostates) as well as in a variety of nonaccessory sex organs. When [ 3 H]estradiol was injected into intact 3- to 4-month-old rats in a pulse dose, no selective accumulation of radioactivity recovered as estradiol was found in the accessory sex glands when compared to other organs. This was due at least in part to the metabolism of estradiol to estrone and to the relatively low concentration of high affinity estrophilic molecules in the accessory sex organs. The order for the rate of formation of estrone from estradiol in tissues obtained from intact animals was ventral prostate > lateral and dorsal prostate > anterior prostate and seminal vesicles. Steroid specificity studies for cytosol estradiol binding by the ventral prostate and seminal vesicles revealed that estrophilic molecules exist in these organs. Based on Scatchard plot analyses in 24-h castrates, the number of available estradiol binding sites was too low in the ventral prostate to quantify accurately, but the seminal vesicles contained distinctly more estrophilic activity than the ventral prostate. The affinity for the seminal vesicle cytosol estradiol-estrophile binding exceeded that quantified for the seminal vesicle dihydrotestosterone-androphile reaction while the number of estradiol binding sites was less than that quantified for dihydrotestosterone. In relation to the accessory sex organs of other species, the rat seminal vesicles have a relatively small amount of cytosol estrophile. The findings that the seminal vesicles catabolize less estradiol and contain significantly more estrophilic activity than the ventral prostate is consistent with and offers insight into the noted estrogenic sensitivity of the seminal vesicles and lack thereof in the rat ventral prostate. With aging of the rat from 3–4 months to 22–26 months, the affinity of the seminal vesicle estradiol-estrophile interaction was unchanged but the number of binding sites increased significantly.

A difference in the in vitro accumulation and metabolism of testosterone -1,2-3H by the rat prostate gland following incubation with ovine or bovine prolactin

Abstract The in vitro actions of ovine or bovine prolactin on the accumulation and metabolism of testosterone-1,2-3H by various lobes of the rat prostate gland were examined. Ovine prolactin at a concentration of 2 IU/ml of incubation media significantly increased the accumulation of total radiosteroid by the anterior and dorsal lobes of the rat prostate gland. Although the levels of both testosterone-1,2-3H and its principle metabolite 5α-dihydrotestosterone-1,2-3H were increased by this concentration of ovine prolactin, the ratio of the two steroids was not altered. Ovine prolactin did not alter either the accumulation or metabolism of testosterone-1,2-3H by the ventral or lateral lobes of the rat prostate gland. In contrast to ovine prolactin, bovine prolactin in a wide range of concentrations (0.02–8 IU/ml) significantly reduced the accumulation of total labeled radiosteroid by the dorsal lobe of the rat prostate gland. The reduction in total radiosteroid was reflected in concomitent decreases in both testosterone-1,2-3H and 5α-dihydrotestosterone-1, 2-3H. The anterior lobe responded with similar reductions but only at relatively high concentrations of bovine prolactin (4 and 8 IU/ml). No significant alterations were observed in either the ventral or lateral lobes as a result of incubation with bovine prolactin.

Protein Kinase C Mediated Anti-Proliferative Glucocorticoid-Sphinganine Synergism in Cultured Pollard III Prostate Tumor Cells

PURPOSE Experimental effort focused on the growth inhibition of an androgen-resistant prostatic carcinoma, using pharmacological inhibition of protein kinase C (PKC) as the therapeutic target. MATERIALS AND METHODS Studies were performed in cell culture using the Pollard (PA) III androgen-insensitive spontaneous rat prostate tumor cells, and the human prostate tumor lines, PC-3 and LnCaP. Pharmacological agents included steroid hormones and PKC modulators; measured parameters of tumor growth/function included cell number, PKC activity and sphingolipid metabolism. RESULTS Triamcinolone (TA) and sphinganine synergized to inhibit the proliferation rate of PA III prostate tumor cells by converging through separate mechanisms to inhibit protein kinase C. At five days of cell culture, 0.1 microM TA reduced both the soluble and particulate forms of PKC in association with a 35-40% reduction in cellular proliferation. Exogenous sphinganine, a competitive inhibitor at the regulatory domain of PKC had no anti-proliferative effect at 1 microM, but in combination with TA synergized to reduce proliferation 80-90%, three days in advance of any detectable inhibitory effect of TA alone on cell number. TA produced no discernable stimulation of endogenous free sphingosine production as evidenced by the lack of an effect on the activity of neutral membrane sphingomyelinase or in the turnover of total cellular sphingomyelin. Phorbol esters, but not cell permeable diglycerides, prevented the TA + sphinganine effect suggesting that a stable long term PKC activation was required for reversal. Steroid specificity studies of the synergistic response revealed that while other glucocorticoids mimicked TA, aldosterone was less active and representatives of the three major classes of sex steroids were inert. Tests of sphinganine specificity demonstrated that calphostin C, a chemically unrelated inhibitor of the regulatory site of PKC, also produced a supra-additive interaction with TA. Ceramides (C2 & C6), which were closely related chemically to sphinganine but lacked affinity for the regulatory subunit of PKC, were inactive in this system. Analyses of the cellular specificity of the TA-sphinganine synergism using the human prostate carcinoma cell lines PC-3 and LnCap revealed a true synergistic growth inhibition in the glucocorticoid receptor positive PC-3 line and no significant interaction in the glucocorticoid receptor negative LnCap cells. CONCLUSIONS TA-induced reduction of PKC concentration coupled with sphinganine antagonism of PKC activation contributed to in a synergistic growth inhibition of an androgen resistant prostatic carcinoma.

The Hormonal Maintenance and Restoration of Guinea Pig Seminal Vesicle Fibromuscular Stroma

Using the separated epithelium and muscle preparation of the guinea pig seminal vesicle, we designed studies to investigate the hormonal control of epithelial collagen, muscle collagen and muscle cells. All hormone treatment regimens involved a comparison of the effects of hormone maintenance (homrone treatments initiated on the day of castration) versus hormone restoration (hormone treatments initiated after a castration-induced regression) on these 3 components of the fibromuscular stroma. In the epithelium, castration induced a 35 per cent decline in collagen content, which was either returned to normal by androgen restoration of prevented by androgen maintenance. In all androgen treatment regimens, changes in epithelial collagen correlated with changes in epithelial wet weight, cell number, RNA content and cell size. In contrast, growth of the epithelium was not stimulated by estrogen maintenance or restoration. Castration reduced muscle wet and dry weight, as well as cell size and RNA content, but there was no effect on cell number and collagen content. Androgen maintenance or restoration reversed the castration-induced regression in all parameters and also caused collagen content to increase 35 percent above normal. Estrogen maintenance of castrates sustained wet weight, dry weight and RNA content at normal and stimulated supranormal increases in both collagen content and cell number. Similarly, estrogen restoration induced supranormal increases in collagen content and returned RNA content to normal. However, estrogens ability to stimulate supranormal increases in cell number and restore wet and dry weight to normal was lost after a castration-induced muscle regression. In summary, components of the guinea pig seminal vesicle fibromuscular stroma have been shown to be sensitive to androgens and/or estrogens. The action of androgen on these tissue components was independent of the state of tissue regression, whereas with the exception of RNA and collagen content all the effects of estrogen were significantly reduced with castration-induced regression of the tissue.

Estrophilic molecules in the male guinea pig.

Abstract Following the intravenous administration of [ 3 H]-estradiol (300 μCi/kg) to mature male guinea pigs, the sex-accessory tissues (seminal vesicle muscle, seminal vesicle epithelium and prostate gland) and kidney incorporated greater concentrations of the native steroid than the liver, ileum, skeletal muscle or plasma. The seminal vesicle muscle was generally able to concentrate the greatest amount of [ 3 H]-estradiol. With a series of in vitro experiments, it was determined that these high concentrations of radioactivity associated with the sex-accessory tissues were not the result of active transport systems. However, it appears as if high affinity, steroid specific cytosolic estradiol binding molecules may serve as the intracellular determinants for the tissue selective distribution and retention of [ 3 H]-estradiol in vivo . Using Scatchard plot analyses, it was found that the seminal vesicle muscle possessed both the greatest concentration of estradiol binding sites and the highest equilibrium association constant. The cytosolic binding activities of the seminal vesicle epithelium, prostate gland and kidney were less than that of the seminal vesicle muscle but in great excess of the liver, skeletal muscle or plasma. These findings suggest that estradiol may potentially be a significant contributor to the function of sex-accessory tissue smooth muscle.

Effect of dieldrin on the accumulation and biotransformation of radioactive testosterone by the mouse prostate gland

Abstract The oral administration of varying dose (2.5 or 5 mg/kg daily × 10) of dieldrin led to significant reductions in the accumulation of radioactive androgen by the mouse prostate gland. This was reflected not only by a reduction in the total accumulation of tritiated steroid ([3H]T) by prostate gland, but also by a decrease in the concentration of dihydrotestosterone ([3H]DHT). The ratio of [3H]T to [3H]DHT remains, however, similar in treated and control groups. The doses of dieldrin used had little effect upon sex accessory organ weights or prostatic fructose concentration. Dieldrin administration failed to alter gonadal weights. There was no change in the hepatic formation of radioactive dihydrotestosterone, androstanediol or androstenedione from [1,2-3H]testosterone in the dieldrin-treated animals, but dieldrin did produce increases in liver androgen hydroxylase activity. While the amounts of dieldrin used in these studies were quite high, the results, nevertheless, indicate that this organochloride could represent a potential deleterious chemical from the standpoint of the male reproductive system.

The influence of aging on androgen dynamics in the male rat

Abstract Androgen assimilation was investigated in a variety of accessory sex organs (seminal vesicles and anterior, dorsal, lateral, and ventral prostates) and in several nonaccessory sex organs in male Wistar rats. After administration of a pulse dose of [3H]testosterone in vivo to intact young (3–4 months old) rats, [3H]testosterone was the primary radioactive steroid recovered from most organs examined, except for the secondary sex glands where the reduced metabolites, [3H]5α-dihydrotestosterone (DHT) and [3H]5α-androstanediol(s), predominated. At longer postinjection times, [3H]DHT was preferentially retained in the accessory sex glands, presumably reflecting intracellular metabolism of [3H]testosterone to this compound and subsequent specific binding of [3H]DHT to receptor proteins. At the longest postinjection interval investigated, the ventral prostate retained greater concentrations of [3H]DHT than the lateral prostate which in turn had a higher [3H]DHT concentration than the seminal vesicles or anterior or dorsal prostates. The latter three glands retained approximately equal concentrations of [3H]DHT. Scatchard plot analyses of cytosol binding in 24-h castrates indicated that with one exception, the level of high affinity DHT binding sites was generally correlated with the retention of [3H]DHT in vivo in intact rats. Specifically, while the affinity for DHT binding in all accessory sex organs was the same, the number of high affinity binding sites per mg wet tissue weight was on the order of ventral prostate > anterior prostate ≥ seminal vesicles ≥ dorsal prostate > lateral prostate. Studies of the influence of aging to 22–26 months revealed no apparent differences in the affinity of the DHT receptor for its ligand in any of the accessory sex glands from 24-h castrates when the receptors were present in levels sufficiently high to quantify. The concentration of available DHT receptors with advancing age remained constant in the anterior and dorsal prostates, increased in the seminal vesicles, and declined in the ventral and lateral prostates. The decreases observed in the ventral prostate were only partial, but the receptors of the lateral prostate declined to nondetectable levels.