Microdialysis of extracellular noradrenaline in the hippocampus of the rat after long-term alcohol intake.

Intracerebral microdialysis combined with high-performance liquid chromatography and electrochemical detection was used to study the effect of chronic ethanol intake on the release of noradrenaline in the hippocampus of the awake, freely moving rat. The hippocampal sites were perfused with an artificial cerebrospinal fluid for 30 min at a rate of 2 microliter/min before ethanol intake and after one and 3 months of ethanol intake. The animals received a 10% ethanol solution as their drinking fluid. The basal release of noradrenaline before ethanol drinking varied from no measurable value to 28 pg in 50 microliters perfusate, possibly being dependent on the behavioral state of the animal. After one month of drinking the release had increased in 4 rats, was lower than before in two animals and remained unchanged in 3 rats. After 3 months of ethanol intake the release had increased in 7 rats out of the 9 and had remained unchanged in two. The mean amount of noradrenaline in 50 microliters perfusate after 3 months of drinking was 52 pg. Five rats out of 9 increased their ethanol consumption during the last two months. The results suggest that chronic ethanol intake affects the release of noradrenaline in the hippocampus, but that the effect is probably dependent on the duration of intake.