NADPH-diaphorase reactivity is reduced in the molecular layer but increased in the granular layer of primate cerebellum after prolonged anaesthesia.

To test if nitric oxide (NO) is involved in modulation of neuronal activity after global changes of brain function, nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reactivity in the cerebellar cortex was compared in monkeys maintained under anaesthesia for 24-48 h with others only anaesthetised for perfusion. After prolonged anaesthesia, NADPH-d activity was reduced in the molecular layer, but increased in the granular layer, with the maintenance of a parasagittal patchy organisation of the highly reactive granule cells. Selective labelling of NADPH-d in the infraganglionic plexuses deep to a subset of Purkinje cell somata was lost in the anaesthetised animals. This differential alteration of NADPH-d reactivity suggests that NO may play a role in regulation of neuronal and synaptic activity during anaesthesia.