Pinealectomy modifies the thermoregulatory effects of bombesin in goldfish

Intraventricular administration of the neuropeptide, bombesin, to intact and sham-pinealectomized fish significantly decreased their behaviorally selected internal body temperatures in horizontal thermal gradients. A behavioral hypothermia of 4-7 degrees C was evident regardless of the previous acclimatization temperature (10 or 25 degrees C) and preferred body temperatures selected by individual fish. Pinealectomy increased the body temperatures of all control fish by 2-4 degrees C while markedly reducing the hypothermic effects of administration of bombesin. The hypothermic effects of bombesin were most evident in the pinealectomized fish acclimatized to 10 degrees C. The possible relations between neuropeptides and the pineal gland in the regulation of body temperature are considered.