The effects of central and peripheral angiotensin on hypertension and nociception in rats.
Spontaneously hypertensive rats (SHRs) rats have been reported to have decreased sensitivity to pain, but as yet a mechanism has not been identified. This study investigated the effects of subcutaneous and intracerebroventricular (ICV) infusions of angiotensin II on blood pressure, locomotor activity, and tailflick and hot plate latencies in the Wistar-Kyoto (WKY) and outbred Wistar rat. Peripheral but not central administration of angiotensin II (567 micrograms/kg/day) increased hot plate latencies in WKY and Wistar rats to a level equivalent to that observed in the SHR. Peripheral administration of norepinephrine (50 and 100 mg/kg/day) to WKYs increased blood pressure but had no effect on hotplate latency. ICV administration of losartan (1 & 3 mg/kg/day) to SHRs had no effect on blood pressure or nociception. The results indicate that angiotensin II has a role in the altered pain perception observed in the SHR and that its site of action is peripheral.
Irvine
R J
RJ
Department of Clinical and Experimental Pharmacology, University of Adelaide, Australia.
White
J M
JM
D000700:Analgesics / Q000627:therapeutic use*; D000704:Analysis of Variance; D000804:Angiotensin II / Q000627:therapeutic use*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology; D002552:Cerebral Ventricles; D006973:Hypertension / Q000188:drug therapy*; D007093:Imidazoles / Q000494:pharmacology; D015918:Infusion Pumps, Implantable; D019808:Losartan; D008297:Male; D010146:Pain / Q000188:drug therapy*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D013777:Tetrazoles / Q000494:pharmacology
D000700:Analgesics; D000959:Antihypertensive Agents; D001713:Biphenyl Compounds; D007093:Imidazoles; D013777:Tetrazoles; D000804:Angiotensin II; D019808:Losartan