Changes in cholinergic and opioid receptors in the rat spinal cord, dorsal root and sciatic nerve after ventral and dorsal root lesion

Abstract

Changes in the distribution of 3H-quinuclidinylbenzilate (3H-QNB), 3H-acetylcholine (3H-ACh) and 3H-alpha-bungarotoxin (alpha-BTx) binding sites were studied with the use of quantitative in vitro autoradiography in the L4-L6 segments of rats 7 days after ventral L4-L6-rhizotomies and 24 hours after ligation of the dorsal roots L4-L6. The changes in the binding sites of these ligands and of 3H-etorphine binding sites were also studied in the dorsal roots of the rats operated with dorsal root ligation and in the sciatic nerves (around a ligature) in the rats operated with ventral rhizotomy. After ventral rhizotomy 3H-QNB binding sites in the ipsilateral motor neuron area were decreased by about 25% from 100 +/- 5 to 73 +/- 5 fmol/mg wet weight. After dorsal root ligation 3H-QNB binding sites in the ipsilateral posterior horn were reduced by about 30% from 91 +/- 5 to 64 +/- 7 fmol/mg wet weight. No significant changes in the binding of the other cholinergic ligands in the spinal cords were observed after the operations. In the dorsal root 3H-alpha-Btx and 3H-etorphine binding sites were higher on the distal side of the ligation (3.5 +/- 0.8 and 14 +/- 4 fmol/mg wet weight, respectively) than on the proximal side (0.7 +/- 0.5 and 2.4 +/- 1.2 fmol/mg wet weight, respectively). The same level of 3H-ACh (total, muscarinic and nicotinic) binding was observed on both sides of the ligation. In the sciatic nerve 3H-QNB and total, muscarinic and nicotinic ACh binding sites were higher on the proximal side of the ligation than on the distal side.(ABSTRACT TRUNCATED AT 250 WORDS)