Intraperitoneal administration of
dermorphin caused dose-dependent changes in rats core temperature and tail skin temperature (indicative of compensatory thermoregulatory vasoreactions in rats). The character of these changes depended strongly on the environmental temperature at which the inversion of the
dermorphin-induced thermoregulatory effect was observed. In the cold environment (4-7 degrees C)
dermorphin caused a significant, stable, dose-dependent
hypothermia. In the thermoneutral environment (27-28 degrees C)
dermorphin also caused
hypothermia, but this effect was less pronounced. In the hot environment (31-32 degrees C)
dermorphin caused
hyperthermia.
Dermorphin-induced changes in tail skin temperature indicate that
dermorphin suppresses the thermoregulatory peripheral compensatory vasomotor reactions. Pretreatment with
naloxone attenuated
dermorphin-induced effects on core temperature and partially enhanced vasomotor effects of
dermorphin. The data obtained indicate that
dermorphin affects the core temperature regulation via mu-
opiate receptors, whereas vasomotor effects of the
peptide are probably mediated via
naloxone-insensitive receptors.