[Changes in the ultrastructure of the rat bulbar nuclei caused by kainic acid administration]

The effect of kainic acid (KA) injection into the commissural area of nucleus tractus solitarii (NTS) of rats was studied to evaluate its influence on the ultrastructure of neurons and gliocytes at the site of injection and in the ventrolateral medulla (VM). 30 min after KA injection, in the perikarya of neurons in rostral and caudal NTS and VM the increased number of ribosomes, lysosomes, lipofuscin granules and edema of mitochondria were noted. Giant mitochondria were found in terminals and axons of myelin fibers. 14 days after KA injection, the increased volume of Golgi complex cisterns was found in single neurons in NTS rostral parts, while the neurons of caudal NTS demonstrated pronounced degenerative and destructive changes. During this period, the volume of mitochondria and of vacuoles was increased in dendrites within caudal NTS and VM, where degenerating processes of the nervous cells were found. In gliocytes of caudal NTS, the hypertrophy of cytoplasm was noted with the accumulation of dilated cisterns of endoplasmic reticulum and redistribution of nuclear chromatin. In the same areas of NTS the reaction of endotheliocytes and pericytes, perivascular edema and accumulation of microgliocytes were found. The results obtained indicate the reactive changes in VM in response to intracentral injection of neurotoxin.