Ki. Yoshida et al., CARDIOVASCULAR, THERMAL AND BEHAVIORAL SENSITIZATION TO METHAMPHETAMINE IN FREELY MOVING RATS, The Journal of pharmacology and experimental therapeutics, 267(3), 1993, pp. 1538-1543
Mean arterial blood pressure (MAP), heart rate (HR), body temperature
(BT) and locomotive activity (LA) were measured simultaneously after i
.p. or i.c.v. injection of methamphetamine (MAH) using a biotelemetric
system. The system enabled us to observe the parameters in freely mov
ing rats under minimum stress. MAH (1 mg/kg) given by i.p. injection s
ignificantly increased MAP, HR, BT and LA, as compared with the saline
-control. MAH (5, 50 mug) administered by i.c.v. injection stimulated
responses of HR, BT and LA. After the i.p. injections of MAH (1 mg/kg)
on days 1, 4, 8, 11 and 15, MAH was administered either through i.p.
(1 mg/kg) or i.c.v. (50 mug) route on day 18. In addition to the LA se
nsitization induced by i.p. and i.c.v. administration of MAH, it was f
ound for the first time, to our knowledge, that the repeated i.p. inje
ctions potentiated the responses of MAP and BT to the subsequent injec
tion of MAH through i.p., but not i.c.v., route. The latter finding su
ggests that the sensitization, produced by the repeated i.p. injection
s, affected responses that MAH induced either peripherally or centrall
y through a peripheral humoral factor or an afferent nervous system.