The OECD Program to Validate the Rat Hershberger Bioassay to Screen Compoundsfor in Vivo Androgen and Antiandrogen Responses. Phase 1: Use of a Potent Agonistand a Potent Antagonist to Test the Standardized Protocol

Abstract

The Organisation for Economic Cooperation and Development (OECD) has completed phase 1 of the Hershberger validation intended to identify in vivo activity of suspected androgens and anti-androgens. Seventeen laboratories from 7 countries participated in phase 1, and results were collated and evaluated by the OECD with the support of an international committee of experts. Five androgen-responsive tissues (ventral prostate, paired seminal vesicles and coagulating glands, levator ani and bulbocavernosus muscles, glans penis, and paired Cowper’s or bulbourethral glands) were evaluated. The standardized protocols used selected doses of a reference androgen, testosterone propionate (TP), and an antiandrogen, flutamide (FLU). All laboratories successfully detected TP-stimulated increases in androgen-responsive tissue weight and decreases in TP-stimulated tissue weights when FLU was co-administered. The standardized protocols performed well under a variety of conditions (e.g., strain, diet, housing protocol, bedding). There was good agreement among laboratories with regard to the TP doses inducing significant increases in tissue weights and the FLU doses decreasing TP-stimulated tissue weights. Several additional procedures (e.g., weighing of the dorsolateral prostate and fixation of tissues before weighing) and serum component measurements (e.g., luteinizing hormone) were also included by some laboratories to assess their potential utility. The results indicated that the OECD Hershberger protocol was robust, reproducible, and transferable across laboratories. Based on this phase 1 validation study, the protocols have been refined, and the next phase of the OECD validation program will test the protocol with selected doses of weak androgen agonists, androgen antagonists, a 5α-reductase inhibitor, and chemicals having no androgenic activity.

Luteinizing hormone reduction by the male potency herb, Butea superba Roxb.

“…These changes are in accordance with previous reports (14)(15)(16), but are different from the reported effects of estrogens and ovariectomy (8,18,19).…”

“…In contrast, the serum LH levels of rats from the BS-50 and BS-250 treatments were significantly lower than those of the control DW group at D 31 -D 61 (P < 0.01). The serum LH levels of TP-treated rats started to be lower than those of the DW group from D 16 , and were significantly different on D 31 -D 61 (P < 0.01).…”

“…It was previously reported that B. superba significantly reduced serum testosterone levels with no abnormal appearance of the testicular and epididymal histology or tissue weights. However, this study did not determine if there were any changes in the seminal vesicle (7), the most sensitive organ of androgenic or anti-androgenic activity in the Hershberger bioassay (16,22).…”

“…In contrast to the decline in testicular weight with TP treatment, the seminal vesicle and epididymal weights of the rats increased and the hypertrophy corresponded to mild, though noticeable, histological changes in cell growth and secretion (14,16,17,22). In contrast to the effects of TP, B. superba powder did not alter the serum testosterone, LH, and FSH levels or the weights and histological appearances of the reproductive organs (testis and epididymis) in intact male rats, except that the seminal vesicle weight increased only in the BS-250 group.…”

“…Blood samples (1 mL) were collected at 9:00-10:00 h on the first day and then every 15 days of the study period, designated as D 1 , D 16 , D 31 , D 46 , and D 61 . Immediately after collection, all blood samples were centrifuged at 1000 g at 4°C for 20 min, and sera were used for the determination of testosterone, LH, and follicle-stimulating hormone (FSH).…”