NADPH-D ACTIVITY IN THE ISLANDS OF CALLEJA - A REGULATORY SYSTEM OF BLOOD-FLOW TO THE VENTRAL STRIATUM PALLIDUM/

WE have used dihydronicotinamide adenine dinucleotide phosphate diapho rase (NADPH-d) histochemistry to study the anatomical relationships be tween the islands of Calleja (ICs), ventral striatum (VS) and ventral pallidum (VP), and the perforating branches of the anterior communicat ing and anterior cerebral arteries traversing the olfactory tubercle. The granule cells of the ICs are intensely positive for NADPH-d, a mar ker for neuronal nitric oxide synthase (NOS), and closely surround all arterioles perfusing the VP and most of the arterioles supplying the VS. In contrast, they are not related to the arteries destined for the dorsal striatum. On the ground of the vasodilatory properties of the nitric oxide, we propose that the ICs may play a role in the regulatio n of blood flow to specific centres of the limbic forebrain.