Short-term ethanol administration does not change the total pyramidal neuron number of the rat hippocampus: a stereologic study

Ethanol-Induced Neuronal and Cognitive/Emotional Impairments are Accompanied by Down-Regulated NT3-TrkC-ERK in Hippocampus

AIMS

Ethanol ingestion affects cognition and emotion, which have been attributed to the dysfunction of specific brain structures. Studies of alcoholic patients and animal models consistently identify reduced hippocampal mass as a key ethanol-induced brain adaptation. This study evaluated how neuroadaptation in the hippocampus (Hip) produced by ethanol contributed to related behavioral deficits in male and female rats.

METHODS

Effects of acute, short-term and long-term ethanol exposure on the anxiety-like behavior and recognition memory on adult male and female Sprague-Dawley rats were assessed using elevated plus maze test and novel object recognition test, respectively. In addition, in order to investigate the direct effect of ethanol on hippocampal neurons, primary culture of hippocampal neurons was exposed to ethanol (10, 30 and 90 mM; 1, 24 and 48 h), and viability (CCK-8) and morphology (immunocytochemistry) were analyzed at structural levels. Western blot assays were used to assess protein levels of NT3-TrkC-ERK.

RESULTS

Acute and short-term ethanol exposure exerted anxiolytic effects, whereas long-term ethanol exposure induced anxiogenic responses in both sexes. Short-term ethanol exposure impaired spatial memory only in female rats, whereas long-term ethanol exposure impaired spatial and recognition memory in both sexes. These behavioral impairments and ethanol-induced loss of hippocampal neurons and decreased cell viability were accompanied by downregulated NT3-TrkC-ERK pathway.

CONCLUSION

These results indicate that NT3-TrkC-ERK signaling in the Hip may play an important role in ethanol-induced structural and behavioral impairments.