Seven-day ethanol administration influence on the rat brain histaminergic neurons.

The purpose of the study is to clarify the effect of 7 days of ethanol administration upon brain histaminergic neurons in rats. Male Wistar rats were injected intraperitoneally (i.p.) with 20% ethanol/saline (0.85% NaCl) daily, over 7 days, whereas control rats were given saline. The animals were decapitated 24 h after the 7th injection and samples of hypothalamus were prepared for light and electron microscopy, accompanied by morphometry to examine the histaminergic neurons. It was found that ethanol administration gradually decreased the duration of alcohol-induced sleep and decreased the total amount of histaminergic neurons and the amount of histologically normal neurons, but increased the amount of hypochromic neurons and shadow cells. The histaminergic neuron bodies and nuclei decreased in size. The ultrastructural changes in histaminergic neurons demonstrated activation of their nuclear apparatus, both destruction or hypertrophy and hyperplasia of organelles, especially lysosomes. The histochemical examination revealed the activation of lactate dehydrogenase and acid phosphatase, and inhibition of NADH-, NADPhH, and succinate dehydrogenases. Following 7 days of ethanol administration, histaminergic neurons exhibit the structural signs of hyperactivity, which can be related to neuronal adaptation to the actions of ethanol, and increased behavioral tolerance to ethanol.

Influence of chronic alcohol consumption on histaminergic neurons of the rat brain.

AIMS: To clarify the effect of chronic alcohol consumption on the brain histaminergic neurons in rats. METHODS: Male Wistar rats were given 20% ethanol as the only source of drinking during 6 months, control rats had a free access to water. The samples of hypothalamus were prepared for light and electron microscopy accompanied by morphometry to examine the brain histaminergic neurons of E2 group. RESULTS: Chronic ethanol consumption increased the amount of histologically abnormal forms of histaminergic neurons and decreased the whole amount of E2 histaminergic neurons (for 5%). The neuron bodies and nuclei increased in size and sphericity, the nuclear/cytoplasmic ratio decreased by 15%. The ultrastructural changes in histaminergic neurons demonstrate the activation of their nuclear apparatus, both destruction and hypertrophy and hyperplasia of organelles, especially lysosomes. Chronic ethanol consumption induces the disturbances in cytoplasmic enzymes of neurons: increases the activity of type B monoamine oxidase, dehydrogenases of lactate and NADH and, especially, marker enzyme of lysosomes acid phosphatase as well as inhibits the activity of dehydrogenases of succinate and glucose-6-phosphate. CONCLUSION: Chronic alcohol consumption affects significantly the structure and metabolism of the brain histaminergic neurons, demonstrating both the neurotoxic effect of ethanol and processes of adaptation in those neurons, necessary for their survival.