Exp Neurobiol 3:29-38, 1994

Distribution of substance P- and calcitonin gene-related peptide- immunoreactive visceral afferent neurons in the dorsal root ganglia of the rat.

Ho Yoon, Won Taek Lee, Kyung Ah Park

Department of Anatomy, Yonsei University College of Medicine, Seoul 120-752, Korea

Although substance P (SP) and calcitonin gene-related peptide (CGRP) are well known as neurotransmitters concerned in pain transmission, there is no information about the number or size distribution of visceral primary afferent neurons containing SP and CGRP of the rats.

T9-T11 ventral and dorsal rami were transected at the right side and 10 days later, T9-T11 dorsal root ganglia (DRG) of both side were obtained. The DRG were cut in 10 зн thickness and each section was stained immunohistochemically against SP or CGRP with peroxidase anti-peroxidase method. The number and the size distribution of the cells with immunoreactivity were obtained, and the data of the right side were compared with those of the contralateral side.

From entire DRG cells 12.02 % had SP immunoreactivity and 11.67 % had CGRP-immunoreactivity, at the control (left) side. The percentage of visceral afferent neurons in SP- or CGRP-immunoreactive cells was less than 43.00 % and 15.59 %, respectively.

The peak incidence of total SP immunoreactive cells was in the range of 200-300 зн2 and that of visceral afferent SP immunoreactive cells was 300-400 зн2. In the case of CGRP immunoreactive cells, peaks of the two groups were at 300-400 зн2, but visceral afferent cells were slightly larger than somatic afferent cells.

Key words: dorsal root ganglia, visceral primary afferent neuron, substance P, calcitonin gene-related peptide