Delta-9-tetrahydrocannabinol: effect on adrenal catecholamines

Abstract

The single ip administration of Δ 9-tetrahydrocannabinol ( Δ 9-THC) at doses of 10 and 50 mg/kg produces a dose-dependent increase in the contents of noradrenaline (NA) and adrenaline (AD) in the rat adrenal gland at the first phase (45–90 min), and thereafter, decline significantly (90–360 min). The content of adrenal dopamine (DA) continues to decrease sharply after the Δ 9-THC administration and remains below normal even after 6 hr. Measurements of turnover of adrenal catecholamines made with the use of FLA-63, an inhibitor of dopamine β-hydroxylase and α-methyl-p-tyrosine (α-M-pt), an inhibitor of tyrosine hydroxylase, show that Δ 9-THC given acutely both at low and at high dose (a) decreases the rate of synthesis and increases the rate of depletion of DA, (b) decreases the rate of depletion of NA and (c) increases the rate of depletion of AD. Treatment with Δ 9-THC (10 mg/kg/day) for 21 consecutive days significantly elevates only the AD content with increase in its turnover rate. The cardiovascular responses, reported to occur after Δ 9-THC administration, appear to be consistent with the increased adrenaline release observed in the present study.