Cholinergic markers in the plasticity of murine barrel field

Cholinergic muscarinic receptor binding and acetylcholinesterase (AChE) histochemistry were studied in the barrel cortex of adult, vibrissae deprived and vibrissae denervated mice. In the control barrel field muscarinic receptors labeled with [3H]quinuclidinyl benzilate ([3H]QNB) showed a higher density in the granular cortex and a higher accumulation of label in the barrels. AChE staining revealed a punctuated pattern corresponding to the barrels in the upper part of layer IV and a reverse-image pattern of staining showing only the walls of barrels in the lower part of layer IV. Neonatal denervation of rows of vibrissae lowered both binding of [3H]QNB to the tissue in the shrunken rows and AChE activity in the denervated rows of barrels. Deprivation and late denervation produced no effects on either pattern, or intensity, of [3H]QNB labeling and AChE staining. These observations suggest that the changes in cholinergic markers are related to the altered morphological structure and not to the abnormal functioning of the barrel cortex which received reduced sensory input from the vibrissae.