Tyrosine hydroxylase activity in the brain and adrenal gland of rats following chronic administration of ethanol.

The effects of chronic administration and ethanol withdrawal on the activity of tyrosine hydroxylase were examined in the adrenal gland and six brain regions, including the frontal cortex, hippocampus, locus coeruleus, striatum, substantia nigra, and hypothalamus. Ethanol was administered to rats by oral intubation every 8 hr for 48 hr in amounts based upon their state of intoxication. One hr after the last intubation, tyrosine hydroxylase activity was not significantly different from control values in either the adrenal gland or brain. Forty hr following the last ethanol intubation, tyrosine hydroxylase activity was significantly increased above control values in both the adrenal gland and locus coeruleus. Tyrosine hydroxylase activity in the remaining five brain areas was unaffected by ethanol treatment. Immunotitration studies indicate that the increases in tyrosine hydroxylase activity found in the adrenal gland and locus coeruleus 40 hr after ethanol administration were due to an increase in enzyme protein. These data indicate that high blood ethanol concentrations maintained over a period of time (48 hr) do not affect adrenal gland or brain tyrosine hydroxylase activity. However, withdrawal from ethanol following 48 hr of treatment does produce an increase in tyrosine hydroxylase activity in the adrenal gland and locus coeruleus, similar to that seen following other stresses.