Effects of in utero MSF exposure on behavior, sleep and cholinergic markers
The present proposal intends to characterize the behavior and some cholinergic markers in rats exposed in utero to methanesulphonyl fluoride (MSF) by examining the potential contribution of acetylcholinesterase to the development of the brain, and the potential consequences that result from the in utero exposure to this acetylcholinesterase inhibitor. Starting with observations and analysis of these rats behaviors, the ultimate objective is to relate the observed behavioral changes with cholinergic neurochemical modifications, occurring in several selected brain areas in such animals. Our working hypothesis is that these rats will show behavioral changes, attributable to a hypercholinergic tone, in at least some parts of the brain. To test this hypothesis, measurements of different cholinergic markers (acetylcholinesterase activity, choline uptake and determination of choline acetyltransferase (ChAT)) were made in five brain areas (frontal cortex, hippocampus, pons, diencephalons and striatum). We have consistently found that MSF exposed rats show a deficit in spatial learning tasks, but only when these tasks employ an appetitive stimulus. On the other hand, when aversive stimuli are used, MSF exposed rats perform equally well or better than the controls, suggesting a possible alteration to the perception of stress in these animals. Tests of anxiety however show no changes in the basal levels of anxiousness. Similarly, tests of affect show no preexisting depressive states in these animals. However, sleep measures indicate a higher level of REM sleep which is only seen during the light phase of males exposed in utero to MSF (females were not tested). No significant changes in the cholinergic markers were found with the exception that MSF exposed females had a higher level of ChAT activity in the synaptosomal fraction from the hippocampus. All together, these neurochemical measures do not support the notion that a higher cholinergic tone exists in specific brain regions of MSF exposed rats, but other measures are needed in order to conclude that no changes in cholinergic tone result from in utero MSF exposure.
Cellular biology|Anatomy & physiology|Animals
Carcoba, Luis Miguel, "Effects of in utero MSF exposure on behavior, sleep and cholinergic markers" (2005). ETD Collection for University of Texas, El Paso. AAI3167937.