Neonatal treatment with capsaicin influences hormonal regulation of blood pressure in adult, water-deprived Long-Evans but not Brattleboro rats.

Conscious, adult, water-deprived Brattleboro rats treated neonatally with capsaicin or vehicle showed similar hypotensive responses to sequential inhibition of the renin-angiotensin system (with captopril) and antagonism of ganglionic transmission (with pentolinium). Following a comparable experimental protocol, Long-Evans rats treated neonatally with capsaicin showed a more marked hypotensive response to captopril administration than did vehicle-injected animals. Furthermore, following administration of captopril and pentolinium, the capsaicin-treated animals showed marked impairment of the vasopressin-dependent recovery of blood pressure. These results indicate that the greater hypotensive response to captopril in water-deprived. Long-Evans rats treated neonatally with capsaicin may be due to less effective compensation for inhibition of the renin-angiotensin system when vasopressin release is impaired.