title: Influence of pertussis toxin on thermic responses to morphine and neurotensin in rats.
abstract: The influence of pertussis toxin (PTX) on thermic responses elicited by morphine and neurotensin was evaluated in unrestrained rats kept at 22 degrees C. High doses of morphine (9-36 micrograms/rat i.c.v.) lowered body temperature and low doses (1.25, 2.5 micrograms/rat i.c.v.) produced hyperthermia. The hyperthermic effect was more resistant than the hypothermic effect to naloxone antagonism. Neurotensin (50, 100 micrograms/rat i.c.v.) induced marked hypothermia followed by hyperthermia. I.c.v. injection of PTX (1 microgram), six days before morphine (18 micrograms/rat i.c.v.), replaced the opiate hypothermia by consistent hyperthermia and reduced by 60% the hyperthermia elicited by morphine (2.5 micrograms/rat i.c.v.). The toxin also affected the thermic responses induced by neurotensin (50 micrograms/rat i.c.v.) administered six days after PTX (1 microgram/rat i.c.v.). The initial hypothermia was enhanced by 173% and the late hyperthermia was fully antagonized. It thus appears that PTX-sensitive G-proteins play different roles in the molecular events underlying the thermoregulatory responses to morphine and neurotensin.
authors.affiliation: Institute of Pharmacology, Faculty of Sciences, University of Milan, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Basilico
authors.forename: M
authors.initials: M
authors.lastname: Abbondi
authors.forename: A
authors.initials: A
authors.lastname: Fumagalli
authors.forename: D
authors.initials: D
authors.lastname: Parolaro
authors.forename: E
authors.initials: E
authors.lastname: Gori
authors.forename: G
authors.initials: G
authors.lastname: Giagnoni
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D004347:Drug Interactions; D005260:Female; D007276:Injections, Intraventricular; D009020:Morphine / Q000494:pharmacology*; D009496:Neurotensin / Q000494:pharmacology*; D037342:Pertussis Toxin; D051381:Rats; D017207:Rats, Sprague-Dawley; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
chemical_list: D010566:Virulence Factors, Bordetella; D009496:Neurotensin; D009020:Morphine; D037342:Pertussis Toxin