Effects of alpha-MSH on motivation, vigilance and brain respiration.
In a series of experiments designed to assess the effects of alpha-MSH on various motivational processes, it was observed that the hormone can slightly decrease food intake and increase water consumption during the first hr after administration in rats. alpha-MSH also modified avoidance behavior in 1- and 3-day-old chicks, but there were no reliable effects on activity, distress vocalizations and the tonic immobility response. alpha-MSH appeared to modulate the sleep-waking activity of rats, and the most prominent effect was an increase of slow wave sleep during the 2-3 rd hr after treatment. A possible second effect was a homogenization of sleep patterns--with poor sleepers exhibiting increases of activated sleep and good sleepers a reduction. Measurement of in vitro brain oxygen consumption indicated that mice treated with alpha-MSH exhibit an 18% reduction in respiration of the brain stem section which includes the locus coeruleus, but did not reliably change respiration in forebrain cortices. alpha-MSH also produced a modest 14% increase of plasma glucose. These results are discussed in terms of possible modulation by alpha-MSH of activity in central autonomic cell groups such as the locus coeruleus.
D000818:Animals; D000831:Animals, Newborn; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects; D001921:Brain / Q000187:drug effects*; D001933:Brain Stem / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D002645:Chickens; D004327:Drinking Behavior / Q000187:drug effects; D004569:Electroencephalography; D005247:Feeding Behavior / Q000187:drug effects; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology*; D051379:Mice; D009042:Motivation; D009928:Organ Specificity; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D012890:Sleep / Q000187:drug effects; D012894:Sleep Stages / Q000187:drug effects; D014851:Wakefulness / Q000187:drug effects*
D009074:Melanocyte-Stimulating Hormones