Body temperature elevation, exercise and serum prolactin concentrations.

Ten young healthy normal-weight males were studied in four test situations designed to elucidate the relative role of body temperature increase vs that of exercise per se for pituitary hormone release. Tympanic temperature was recorded continuously during the tests. Elevation of body temperature at rest induced by external heating resulted in parallel changes in serum prolactin (Prl), also found when temperature spontaneously returned towards normal. In contrast, temperature elevation of the same magnitude through exercise (450 kpm/min for 40 min) induced no change in Prl secretion. It is concluded that increase in core temperature is a stimulus of Prl secretion and suggested that exercise apparently inhibits the stimulatory effect.