SELECTIVE LOSS OF CHOLINERGIC RECEPTORS FOLLOWING UNILATERAL INTRACORTICAL INJECTION OF VOLKENSIN

Experimental lesions and quantitative autoradiography were used to inv estigate the cellular distribution of neurotransmitter receptors in ra ts. Lesions were produced by intracortical injections of either volken sin or ricin. However, only the former is retrogradely transported and volkensin treatment causes significant loss of contralateral cortical pyramidal neurones. Binding of [H-3]pirenzepine (muscarinic M-1 recep tors) and [H-3]nicotine was reduced in contralateral cortex in volkens in compared with ricin and/or control (uninjected) animals. However, b inding of [H-3]8-hydroxy-2-(n-dipropylamino)tetralin (5-HT1A receptors ), [H-3]ketanserin (5-HT2A receptors), and [H-3]1,3-dipropylcyclopenty lxanthine (adenosine A(1) receptors) was unchanged. The most likely ex planation for these results is that M-1 and nicotinic receptors are pr esent in large numbers on those pyramidal neurones that are lost. The results are discussed in terms of the biology of cortical pyramidal ne urones, drugs for Alzheimer's disease, and novel ligands for improving human brain scanning techniques. (C) 1997 Academic Press.