Captopril given intracerebroventricularly, subcutaneously or by gavage inhibits angiotensin-converting enzyme activity in the rat brain.
In rats with permanent brain cannulas intracerebroventricular (i.c.v.) injections of 2 microgram captopril nearly abolished drinking responses elicited by i.c.v. injections of 1 mUnit hog renin, 10 pmol synthetic renin substrate or 10 pmol angiotensin I but did not reduce drinking elicited by 10 pmol angiotensin II. Inhibition of the response to precursors of angiotensin II was long-lasting (at least 2 h) and dose-dependent (20 ng-2 microgram captopril). Captopril was 3-5 times more potent than SQ 20,881 i.c.v. Subcutaneous injections of captopril in doses 0.1 to 1.0 mg/kg reduced pressor responses to intravenous injections of angiotensin I without attenuating drinking elicited by i.c.v. injections of angiotensin precursors. Higher doses of captopril, however, given subcutaneously (5-50 mg/kg) or by gavage (10 mg/kg) did not reduce drinking to i.c.v. injections of renin or angiotensin I (but not angiotensin II). We conclude that captopril inhibits angiotensin-converting enzyme activity in the brain even when given subcutaneously or by gavage in doses commonly used in the rat.
D000806:Angiotensin-Converting Enzyme Inhibitors; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002216:Captopril / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D007279:Injections, Subcutaneous; D007441:Intubation, Gastrointestinal; D008297:Male; D011392:Proline / Q000031:analogs & derivatives*; D051381:Rats; D012083:Renin / Q000494:pharmacology
D000806:Angiotensin-Converting Enzyme Inhibitors; D011392:Proline; D002216:Captopril; D012083:Renin