Effects of ageing and intermittent ethanol exposure on rat locus coeruleusand ethanol-withdrawal symptoms

In this study, the effects of ethanol and ape on the morphology of the locu s coeruleus (LC) and on the severity of ethanol-withdrawal symptoms were st udied during a 5-week intermittent ethanol exposure. Young (3-4 months) and old (29-30 months) male Wistar rats were given highly intoxicating doses o f ethanol by intragastric intubations for 4 days, followed by a 3-day ethan ol-withdrawal period. This 7-day cycle of ethanol exposure and withdrawal w as repeated five times. A non-treated group and a sucrose-fed group of both ages were used as control groups. The severity of ethanol-withdrawal sympt oms (rigidity, tremor, irritability, hypoactivity) was rated up to 62 h aft er the last dose of ethanol. The intoxication level was higher in the old, compared with the young, rats, despite the smaller doses of ethanol given t o the old animals. There was no significant difference between the age grou ps in the severity of the ethanol-withdrawal syndrome. The LC quantitative studies were performed using unbiased stereological methods. The results sh owed that there was no difference between the age groups in the LC total ne uron numbers of the non-treated control groups. The 5-week intermittent eth anol exposure significantly reduced the LC neuron numbers and LC neuronal d ensity in the old ethanol-exposed animals, compared with the sucrose-fed co ntrol animals. In the young rats, the ethanol-induced neuron loss did not r each statistical significance. According to the ANCOVA, the difference in t he ethanol-induced LC neuronal loss between the age groups may be due to th e difference in the intoxication levels. Interestingly, the sucrose intubat ions were also found to decrease the LC neuronal numbers in the young rats, compared with the non-treated young control group. It was concluded that a geing did not significantly affect the severity of ethanol-withdrawal sympt oms or ethanol-induced loss of LC neurons in Wistar rats.