TitleNEUROPHYSIOLOGICAL EFFECTS OF VASOTOCIN AND CORTICOSTERONE ON MEDULLARY NEURONS - IMPLICATIONS FOR HORMONAL-CONTROL OF AMPHIBIAN COURTSHIP BEHAVIOR
Publication TypeJournal Article
Year of Publication1995
AuthorsRose, JD, Kinnaird, JR, Moore, FL
JournalNeuroendocrinology
Volume62
Pagination406-417
Type of ArticleJournal Article
ISSN0028-3835
Abstract

Research on a wide variety of vertebrates, from fish to mammals, reveals that corticosteroid hormones and vasotocin-like neuropeptides can potently modulate reproductive behaviors. But, it is not clear how the behavioral effects of these chemical messengers relate to functional properties of behavior-controlling neurons. This problem was investigated in the roughskin newt, Taricha granulosa, an amphibian in which the administration of arginine vasotocin (AVT) facilitates and corticosterone (CORT) inhibits courtship clasping of females by males. In waking, immobilized male newts, neurophysiological effects of AVT and CORT were studied in neurons in the rostral medulla due to the probable role of these neurons in the control of clasping. Topical medullary application of a clasp-facilitating dose of AVT produced a rapid increase in neuronal responsiveness to pressure on the cloaca, a trigger stimulus for clasping responses. Neuronal responses to noncloacal somatic stimuli and to moving visual stimuli were also enhanced. Systemic CORT administration, which has previously been shown to depress newt medullary neuronal sensory responsiveness, reversed the action of AVT such that the peptide depressed sensory responsiveness when applied 30 min after CORT. When AVT application prededed CORT injection by 10-17 min, however, the usual suppressive CORT effect was reversed and this treatment resulted in a rapidly appearing potentiation of neuronal activity and enhanced somatic sensory responsiveness. If the interval between AVT and CORT was increased to 30 min, the steroid caused a rapid depression of firing and a diminished somatic sensory responsiveness in most neurons, similar to what occurs in newts treated with CORT alone. These results indicate that neurophysiological actions of AVT or CORT depend on the type of prior hormonal exposure (pretreatment with AVT of CORT) and the time interval between hormone actions.

URL<Go to ISI>://WOS:A1995TA07400011
DOI10.1159/000127030