VODKA, BUT NOT OTHER
ALCOHOLIC BEVERAGES, ACCELERATES RESETTING THE CIRCADIAN CLOCK. S.J.
Moorman, P. Tiwari, and M.K. Desai. Department of Neuroscience
and Cell Biology. Robert Wood Johnson Medical School, Piscataway, NJ.
It has been suggested that consumption of small amounts of
vodka eases the transition to a new time zone. This has generally
been attributed to the soporific affects of the vodka. However,
it is possible that the alcohol has direct effects on the regulation of
circadian rhythm genes. To investigate this possibility, we
generated a transgenic mouse that expresses the gene for an unstable
form of eGFP under the influence of the promoter/enhancer for the mouse
period-2 gene. To circumvent having to kill the mice to evaluate
egfp expression, we also developed an ophthalmoscope with appropriate
excitation and emission filters that allow visualizing GFP fluorescence
in the retinae of live animals. The tper2:egfp mouse expressed
gfp in the retina in a circadian fashion with a periodicity that
parallels the expression of the native per2 gene, i.e. maximal
expression during subjective day and minimal expression during
subjective night. When tper2:egfp mice (n = 24) that were
maintained on a 12/12 hour light/dark cycle (Zeitgeber Time = 12) had
the light cycle abruptly shifted by 6 hours (Zeitgeber Time = 6), it
took 3 days for the circadian expression of GFP to shift so that
expression levels were in phase with the light cycle. This gives
a Zeitgeber-reset ratio (ZRR) of 2 hour/days. Tper2:egfp mice
were then given free access to vodka (n = 24), whiskey (n = 21), beer
(n = 24), red wine
(n = 24), or white wine (n = 24) for 1 hour immediately prior to
changing the Zeitgeber Time to 6. Both behaviour and beverage
consumption were monitored for all animals. The ZRR for each
group was then determined and corrected for the alcohol %-volume
consumption of the group. Only the group that had access to vodka
had a ZRR (5.72, +/- 0.6 SEM) that was significantly different from the
control group (p < 0.001, student-t test). To discount the
possibility that the vodka reset the circadian clock directly,
tper2:egfp mice were kept in constant darkness and allowed free access
to vodka for 1 hour. This group showed no difference in egfp
expression pattern over the next 3 days when compared to a control
group kept in constant darkness. To determine whether the effects
were due to soporifity, we determined the soporific-quotient (SQ = %
time spent sleeping) for each group. Although all experimental
groups had
significantly higher SQs than the control group, the differences
between the experimental groups were not significant. These results
support the idea that consumption of vodka and not other alcoholic
beverages can ameliorate the effects of changes in time zone.
(last revised 31 March 2004)
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