Non-Breeding Gonadal Testosterone Production of Male and Female Northern Cardinals (Cardinalis cardinalis) Following GnRH Challenge

Document Type

Article

Publication Date

12-1-2011

Department

Biological Sciences

School

Biological, Environmental, and Earth Sciences

Abstract

Yearly, testosterone (T) levels fluctuate as many vertebrates cycle through reproductive and non-reproductive periods. Among many temperate birds, it is well established that levels of T peak as gonads recrudesce for breeding and then fall as gonads regress prior to the non-breeding season. While the tissues producing breeding season T are well studied, the tissues responsible for non-breeding T have received less investigative attention. We examined the ability of male and female Northern Cardinals (Cardinalis cardinalis) to elevate gonadal T following standardized injections of gonadotropin-releasing hormone (GnRH) across three non-breeding seasons. Males and females were capable of significantly elevating gonadal T production following GnRH injections during periods of reproductive quiescence. The magnitude of T elevation varied across the non-breeding season, but not between sexes. To our knowledge, this is the first report of a significant increase in gonadal T production following GnRH injections administered in the non-breeding season.

Publication Title

General and Comparative Endocrinology

Volume

174

Issue

3

First Page

370

Last Page

378

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