Regional catecholamine levels in brains of normal and ethanol-tolerant long-sleep and short-sleep mice

Brain regional heterogeneity and toxicological mechanisms of organophosphates and carbamates

The brain is a well-organized, yet highly complex, organ in the mammalian system. Most investigators use the whole brain, instead of a selected brain region(s), for biochemical analytes as toxicological endpoints. As a result, the obtained data is often of limited value, since their significance is compromised due to a reduced effect, and the investigators often arrive at an erroneous conclusion(s). By now, a plethora of knowledge reveals the brain regional variability for various biochemical/neurochemical determinants. This review describes the importance of brain regional heterogeneity in relation to cholinergic and noncholinergic determinants with particular reference to organophosphate (OP) and carbamate pesticides and OP nerve agents.

Intensification of the development of ethanol dependence in mice lacking dopamine D(3) receptor

The present study was designed to ascertain the role of dopamine D3 receptors in the development of physical dependence on ethanol using mice lacking the dopamine D3 receptor gene. The mutation eliminated the dopamine D3 receptor without any detectable changes in both dopamine D1 and D2 receptors. The ethanol-induced sleep time in dopamine D3 receptor knockout mice (D3-KO) was longer than that in wild-type mice. To examine the role of dopamine D3 receptors in the development of physical dependence on ethanol, two genotypes were chronically treated with 7% ethanol according to the liquid diet method. After the termination of ethanol treatment, severe withdrawal signs were observed in D3-KO mice as compared with wild-type mice. The present data suggest that the lack of dopamine D3 receptor genes in the mouse brain leads to the aggravation of the development of physical dependence on ethanol.

Chronic ingestion of ethanol increases the number of Ca2+ channels of hippocampal neurons of long-sleep but not short-sleep mice

Whole cell and single channel Ca2+ currents were compared for hippocampal neurons of normal and ethanol-tolerant long-sleep and short-sleep mice. The properties of these currents were equivalent for normal LS and SS mice. In contrast, the peak amplitude of the whole cell Ca2+ current increased significantly for neurons isolated from LS but not SS mice chronically ingesting ethanol. Since there were no changes in the functional properties of single channel events, these data indicate that chronic ingestion of ethanol causes an increase in the number of functional Ca2+ channels in the membrane of hippocampal neurons of LS mice.