Increase of muscarinic receptor following kainic acid lesions of the nucleus basalis magnocellularis in rat brain: an autoradiographic study.

We observed changes in cholinergic markers in rat brain seven days after lesioning the nucleus basalis magnocellularis (nbm) with kainic acid. In histochemical preparations stained for acetylcholinesterase (AChE), there was a marked loss of large AChE reactive neurons within and beneath the nbm on the injected side, and the AChE positive fibers were greatly decreased particularly in the IV-VI layers of the frontal and parietal cortices ipsilateral to the kainate lesion. Using in vitro receptor autoradiography, we found a significant increase (about 25%) in 3H-QNB binding sites in the I-IV layers of the ipsilateral frontal and parietal cortices (p 0.05, Student's t-test). The area with decreased AChE activity and increased density in 3H-QNB binding sites corresponded to the innervation of the cholinergic system arising from the nbm. The increase of density in 3H-QNB binding sites was considered to reflect the postsynaptic denervation supersensitivity.