Gi proteins and calcium in dynorphin-induced hypothermia and behaviour.

The intracerebroventricular (i.c.v.) administration of pertussis toxin (0.5 microgram) to rats significantly reduced the hypothermic and behavioural effects (episodic bizarre postures characterized by limb rigidity and followed by barrel rolling) induced by i.c.v. dynorphin A (10 micrograms). These central effects of dynorphin A thus appear to be initiated at a receptor site that interacts with G proteins substrates sensitive to pertussis toxin. Dynorphin A-induced hypothermia was also significantly reduced by i.c.v. pretreatment with the Ca2+ antagonist, verapamil (10 micrograms), although verapamil per se did not modify the behavioural effects elicited by the peptide.