Testosterone and opioids interact to regulate feeding in a male migratory songbird.
A male migratory songbird (dark-eyed junco, Junco hyemalis) was used as a model for studies on the influence of testosterone (T) on feeding, and on interactive effects on this behavior between T and the opioid antagonist naloxone hydrochloride (Nal). Administered chronically to birds exposed to nonstimulating photoperiods, T increased food intake by 30-58% without altering the body mass, the fat index, or the standard metabolic rate. An intramuscular injection of Nal decreased feeding temporarily in a dose-related manner. T-treated juncos exhibited a decreased sensitivity to the anorexic influence of Nal administration, demonstrating that T interacts with opioids to control food consumption. Neuroendocrine mechanisms that potentially account for this interaction are discussed.
Deviche
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Institute of Arctic Biology, University of Alaska, Fairbanks 99775.
D000818:Animals; D001717:Birds / Q000502:physiology*; D004723:Endorphins / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D008297:Male; D012621:Seasons; D012741:Sexual Maturation / Q000502:physiology; D012931:Social Environment; D013045:Species Specificity; D013739:Testosterone / Q000097:blood*
D004723:Endorphins; D013739:Testosterone