Distribution of nNOS-containing neurons in rabbit brain stem and their functional changes caused by aging

The research was designed to study the distribution of nNOS-containing neurons in rabbit brain stem and their functional changes for aging by means of SABC immunohistochemistry.The results showed that there are abundance of nNOS-containing neurons in rabbit brain stem;they are mainly distributed in nucleus of oculomotor nerve,red nucleus,pontine nucleus,main sensory nucleus of trigeminal nerve,reticular formation of brain stem.Besides,they also exist aroud the central gray matter,superficial gray matter layers of superior colliculus,parabrachial nucleus,superior central nucleus,hypoglossal nucleus,inferior olivary nucleus,cuneate nucleus etc.The differences of the number of nNOS-containing neurons,mean cross-sectional area of cell bodies and the length of the longest neurite in nucleus of oculomotor nerve,red nucleus,pontine nucleus,main sensory nucleus of trigeminal nerve and lateral reticular nucleus of medulla oblongata among 5 age groups were studied.Compared with those of adult rabbits,the number of nNOS-containing neurons,mean cross-sectional area of cell bodies and the length of the longest neurite did not change significantly (P 0.05) in cub and young group,but the number of nNOS-containing neurons and length of the longest neurite of the elderly rabbits (36 months) were significantly reduced (P 0.05).The average cross-sectional area of cell bodies was reduced in nucleus of oculomotor nerve,pontine nucleus,main sensory nucleus of trigeminal nerve and lateral reticular nucleus,but it was increased in red nucleus(P 0.05).The results suggest that there are abundance of nNOS-containing neurons in rabbit brain stem,which may take part in the activities,sensory and motor conduction of viscera and the regulation of advanced integration function such as sleeping and awakening;The aging of nNOS-containing neurons may influence synthesis and release of NO,thus affecting their physiological function in brain stem.