Thomas M P, Davis M I, Monaghan D T, Morrisett R A
Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas, Austin 78712-1074, USA.
Alcohol Clin Exp Res. 1998 Feb;22(1):51-9.
Assessment of long-term alterations in neural function and phenotype has usually involved culture techniques that utilize dissociated preparations. Recently, we have approached such topics in alcohol research by using brain slice cultures, also known as explant or organotypic preparations. In this symposium presentation, two preparations will be discussed, and examples of the particular advantages of these preparations will be presented in relation to alcohol research. First, we use the hippocampal explant preparation for assessment of long-term alterations in N-methyl-D-aspartate receptor (NMDAR) function due to chronic ethanol exposure and subsequent withdrawal. This preparation displays many synaptic, structural, and enzymatic phenotypes indicative of normal neural preparations. Patch clamp recordings reveal NMDAR-mediated excitatory postsynaptic current (EPSC) elicited upon stimulation of Schaffer collateral fibers and recorded from CA1 pyramidal cells. Long-term ethanol exposure followed by subsequent withdrawal resulted in a specific enhancement of NMDAR-mediated synaptic responses which preceded the expression of epileptiform events that occurred after prolonged withdrawal periods. Second, we describe a novel explant preparation, derived from horizontal slices of the entire forebrain and midbrain of the rat. These long-term explants displayed multiple normal phenotypes including Nissl, AChE, TH, and GFAP staining. Electrophysiologically, these explants displayed a functional corticostriatal pathway recorded with field and patch clamp techniques and elicited by synaptic stimulation. Taken together, these explant preparations display utility for long-term study of ethanol effects on neural systems, especially relating to withdrawal hyperexcitability as well as systems involved in drug-seeking behavior.
