NEUROTENSIN - DISTRIBUTION OF HYPOTHERMIC RESPONSE IN MAMMALIAN AND SUBMAMMALIAN VERTEBRATES

Neurotensin (NT), an endogenous tridecapeptide (pGlu-Leu-Tyr-Glu-Asn-Lys-Pro-Arg-Arg-Pro-Tyr-Ile-Leu-OH), is a potent hypothermic agent after central administration in the mouse and rat. The purpose of the present investigation was to evaluate the effect of NT on thermoregulatory processes in a variety of mammalian and non-mammalian vertebrates: bluegill, frog, lizard, pigeon, ground squirrel, woodchuck, golden hamster, rabbit, guinea pig, gerbil, mouse, rat and monkey. All species except monkey were tested in two ambient environmental temperatures, 23°C and 4°C, except poikilotherms. Animals were injected intracisternally with microgram quantities of NT or vehicle, and body temperature was periodically assessed over a 2 hr period. NT did not induce a significant alteration in body temperature in any of the poikilotherms studied (bluegill, frog, and lizard). At 23°C NT produced a significant hypothermic response in the mouse, rat, gerbil, and monkey with no effect observed in the pigeon, rabbit, guinea pig, golden hamster, ground squirrel or woodchuck. At 4°C, NT produced a significant decrease in body temperature in the mouse, rat, gerbil, guinea pig and golden hamster with no effect evident in the pigeon, rabbit, ground squrrel or woodchuck. Species known to respond to cold by increasing metabolic rate (e.g. mouse and rat) appear to be most responsive to NT. The hypothermic activity of NT in a variety of mammals suggests that the peptide may play a role in thermoregulation. © 1979.