Peripheral innervating region of Leu-enkephalin immunoreactive cells in guinea pig trigeminal ganglion

We previously reported the presence of leucine-enkephalin-like immunoreactivity (Leu-EK-LI) and opiate receptors in trigeminal ganglion (TG) of the guinea pig, and suggested the possible modulation of sensory transmission by Leu-EK in TG. In the present study, we investigated the detailed distribution of Leu-EK-LI cells in TG and Leu-EK-LI fibers in the peripheral region. Furthermore, we examined the effect of peripheral nerve injury on Leu-EK-LI cells and opiate receptors in TG. (1) We observed many ganglionic cells with Leu-EK-LI in the ventromedial and dorsolateral parts of TG. (2)Leu-EK-LI fibers were observed in the nasal mucosa, gingiva and periostium. Some of TG cells labeled by retrograde transport of fluolo-gold from these area had Leu-EK-LI. (3) Injury of infra alveolar nerve reduced the number of Leu-EK-LI cells in TG and tended to decrease 「^^3 H」-DPDPE binding to membrane fraction of TG. These results indicate that Leu-EK-LI cells in TG have some role in sensory transmission in oral and maxillo-facial area.