Regulation of daily rhythm of body temperature by neurotensin receptor in rats.

It is proposed that neurotensin receptor mediated signal transduction may play an important role in the thermoregulatory control in the brain. In this study, a significant increase in body core temperature was observed with SR 48692, a neurotensin receptor antagonist, after treatment of rats at light phase when the temperature is regulated low. On the other hand, SR 48692 delayed the physiological decline of body core temperature at dark phase when the temperature is highly regulated. We also found slight daily rhythmicity, though not significant, in neurotensin/neuromedin N precursor protein mRNA levels in the medial preoptic nucleus using in situ hybridization technique. Our results support the hypothesis that endogenous neurotensin receptor agonists play a physiological role in the central modulation of body core temperature in rats.