Effects of the Endocannabinoid Anandamide on the Efficiency of Noradrenergic Neurotransmission in the Amygdaloid Body in Acute Stress in Mice

The effects of endocannabinoid neurotransmission on corticosterone secretion by the adrenals and release of noradrenaline in the amygdaloid body during acute stress modeled in the elevated platform test were studied by intracerebral microdialysis in C57Bl/6N mice using the CB1 receptor antagonist rimonabant and the anandamide reuptake inhibitor AM-404. Increases in corticosterone secretion on exposure to rimonabant (3 mg/kg, p.o.) confi rmed the role of CB1 receptors in controlling the activity of the hypothalamo-hypophyseal-adrenal (HHA) system and verifi ed their infl uences on the amplitude but not the duration of hormone secretion. Stress was accompanied by a transient increase in noradrenaline release in the amygdaloid body. AM-404 (3 mg/kg, i.p.) suppressed but did not fully inhibit stress-induced noradrenaline release, decreasing it to control levels. The results obtained here provide evidence that the endocannabinoid anandamide is involved in regulating presynaptic noradrenaline release in the amygdaloid body in conditions of psychological stress.