Physiology &Behavior, Vol. 24, pp. 441-446. PergamonPress and Brain Research Publ., 1980. Printed in the U.S.A. Further Evidence that Androgen Aromatization is Essential for the Activation of Copulation in Male Quail E. K. ADKINS, J. J. BOOP, D. L. KOUTNIK, J. B. MORRIS AND E. E. PNIEWSKI Department of Psychology and Section of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853 Received 6 October 1979 ADKINS, E. K., J. J. BOOP, D. L. KOUTNIK, J. B. MORRIS AND E. E. PNIEWSKI. Furtherevidence that androgen aromatization is essentialfor the activation of copulation in male quail. PHYSIOL. BEHAV. 24(3) 441--446, 1980.rain Experiment 1 male quail (Coturnix coturnixjaponica) with photically regressed testes were implanted intraperitoneally with Silastic tubing containing either testosterone propionate (TP), testosterone (T), androstenedione (AE), 17a- methyltestosterone (MT), estradiol benzoate (EB), dihydrotestosterone propionate (DHTP), 6a-fluorotestosterone prop- ionate (FTP), fluoxymesterone (FM), or cholesterol (CHOL), or were implanted subcutaneously with pellets of FTP. All steroids except EB and FM stimulated proctodeal gland development, and all except MT, EB, and FM stimulated crowing to a significant extent. When administered as Silastic implants, the only androgens that activated copulation were TP, T, and AE. Subcutaneous pellets of FTP also activated copulation. In Experiment 2 male quail with photically regressed testes were injected with TP, TP + ATD (1,4,6-androstatrien-3,17-dione, an aromatase inhibitor), EB, EB + ATD, or oil. ATD completely blocked TP-stimulated copulation, but had no effect on EB-stimulated copulation. These experiments provide further evidence for an aromatization theory of quail copulation. Coturnix quail Crowing Androgens Sexual behavior Aromatization Proctodeal gland EVIDENCE is accumulating that conversion (aromatiza- tion) of testosterone to estrogen is important or even essen- tial for the activation of copulatory behavior in male rats and sheep [17, 29, 31] and for the activation of aggressive behav- ior in male mice [12]. Particularly compelling are those studies in which testosterone is administered together with a second substance that inhibits aromatization, with the result that the testosterone is now incapable of stimulating sexual or aggressive behavior [14,26]. The importance of androgen aromatization for behavior may extend to certain species of birds as well as mammals. Both testosterone (T) and estradiol (E) activate wing-flipping (a component of the nest-soliciting display) in male ring doves, but dihydrotestosterone (DHT), a nonaromatizable androgen, does not [2, 22, 34]. Similarly, either T or E, but not DHT, activates copulation in male domestic chickens [8,39]. Among avian species the role of androgen aromatiza- tion has been most extensively studied in Japanese quail (Coturnix coturnixjaponica). In this species the antiestrogen nitromifene citrate (CI-628) blocks T-stimulated copulation [5]. In addition, either T or E, but not DHT, activates copu- lation [1, 3, 6]. In contrast, a second component of repro- ductive behavior, crowing, and a peripheral structure, the proctodeal (foam) gland, respond readily to DHT, but not to E, and therefore do not seem to have a mechanism involving androgen aromatization [1]. Androstenedione, an aromatiz- able androgen, fails to stimulate copulation when injected, but is somewhat more effective when administered as sub- cutaneous solid pellets; androsterone, a nonaromatizable androgen, is quite weak peripherally, and so no conclusions can be drawn from its failure to activate behavior [1]. The experiments reported here were conducted in order to further test the aromatization theory of quail copulation. The purpose of Experiment 1 was to reexamine the ability of aromatizable vs nonaromatizable androgens to activate sexual behavior in male Japanese quail, using a continuous mode of administration (Silastic implants) that more closely mimics testicular output, and using a greater variety of an- drogens, including three whose behavioral effects have not been previously studied in birds: 6a-fluorotestosterone prop- ionate, fluoxymesterone, and 17a-methyltestosterone. The purpose of Experiment 2 was to see whether the aromatase inhibitor 1,4,6-androstatrien-3,17-dione (ATD) blocks T- stimulated copulation in male quail. EXPERIMENT 1 METHOD Animals The subjects were mature, sexually-experienced Japa- 1This research was supported by grant BNS-7624308 from the National Science Foundation to the first author, and by the College of Arts and Sciences, Cornel University. We thank Joyce Swartzman and Evelyn Hurvitz for technical assistance, and Dr. P. W. O'Connell of the Upjohn Company for generously providing the 6a-fluorotestosterone propionate. Copyright © 1980 Brain Research Publications Inc.--0031-9384/80/030441-06502.00/0