PYRAMIDAL NEURONS IN HUMAN PRECENTRAL GYRUS CONTAIN NITRIC-OXIDE SYNTHASE

PYRAMIDAL cells in the mammalian neocortex do not normally contain det ectable levels of the enzyme nitric oxide synthase. However one region of the human neocortex contains pyramidal neurones that express neuro nal nitric oxide synthase activity. These neurones are mainly located in layer V of the precentral gyrus and frontal cortex and are predomin antly Betz cells. The proportion of Betz cells stained in the eight br ains examined varied from 5 to 80%. The brains of eight rats that had received a stab wound to the parietal cortex were also examined. Follo wing a survival period of 7 or 14 days, small groups of pyramidal neur ones surrounding the lesion contained moderate levels of neuronal nitr ic oxide synthase. We suggest that human pyramidal neurones may start expressing nitric oxide synthase as a response to damage or age-relate d stress and that the nitric oxide released may have a neuroprotective role.