IN VIVO RELEASE OF ENDOGENOUSLY SYNTHESIZED CATECHOLAMINES FROM THE CAT BRAIN EVOKED BY ELECTRICAL STIMULATION AND BY d‐AMPHETAMINE

The cerebral ventricles of spinal‐sectioned cats were perfused with artificial cerebrospinal fluid after the intraventricular administration of [3H]DOPA or [3H]tyrosine. Endogenously synthesized [3H]dopamine or [3H]norepinephrine were identified in the perfusate. Electrical stimulation of catecholaminergic nerve tracts in the hypothalamus increased the efflux of both catecholamines. The addition of d‐amphetamine to the perfusing cerebrospinal fluid caused a large increase in [3H]dopamine and a small increase in [3H]norepinephrine appearing in the perfusate. Most of the endogenously synthesized [3H]catecholamines detected in the perfusate following stimuli originated from structures bordering the lateral cerebral ventricle. Thus, norepinephrine and dopamine can be synthesized in and released from catecholaminergic nerve terminals in structures bordering the cerebral ventricles.