Effects of continuous versus intermittent ethanol exposure on rat sympathetic neurons.
BACKGROUND
Binge ethanol exposure is known to induce degeneration of central nervous system (CNS) neurons. Sympathetic hyperactivity has been related to ethanol withdrawal symptoms, but the effects of repeated withdrawals on peripheral sympathetic neurons have not been studied previously.


METHODS
The effects of continuous versus intermittent ethanol consumption on sympathetic neurons of the superior cervical ganglion (SCG) were studied in male Wistar rats. Two-month-old rats were divided into three groups: one group with ethanol (10% v/v) as the drinking fluid throughout the 51/2-month experiment (continuous, n = 9), one group drinking ethanol on 4 days/week and water on 3 days/week (intermittent, n = 9), and a control group (n = 9) with water as the only available fluid. All groups had food ad libitum. SCG volume, neuron density, and total number of neurons were measured by using unbiased morphometric methods.


RESULTS
As the mean daily ethanol consumption did not differ between the two ethanol-exposed groups (continuous 5.7 g/kg/day versus intermittent 5.8 g/kg/day), the total dose of ethanol consumed was 42% smaller in the intermittent group. The total number of SCG neurons decreased by 28%, and neuron density by 23%, in the intermittent group compared with the control group, whereas no significant neuron loss was observed in the continuous group. The volume of the SCG was similar in all study groups. The results suggest that repeated ethanol withdrawals, rather than ethanol exposure per se, are deleterious to sympathetic neurons.


CONCLUSIONS
Ethanol-induced degeneration of neurons is not only related to the amount of ethanol consumed, but also to the patterns of drinking.
Riikonen
J
J
Tampere School of Public Health, University of Tampere, Finland. jr53087@uta.fi
Jaatinen
P
P
Karjala
K
K
Rintala
J
J
Pörsti
I
I
Wu
X
X
Eriksson
C J
CJ
Hervonen
A
A
D000320:Adrenergic Fibers / Q000187:drug effects* / Q000473:pathology; D000428:Alcohol Drinking; D000818:Animals; D002492:Central Nervous System Depressants / Q000009:adverse effects* / Q000506:poisoning; D000431:Ethanol / Q000009:adverse effects* / Q000506:poisoning; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013375:Substance Withdrawal Syndrome; D017783:Superior Cervical Ganglion / Q000187:drug effects* / Q000473:pathology; D015430:Weight Gain / Q000187:drug effects
D002492:Central Nervous System Depressants; D000431:Ethanol