Immunohistochemical localization of the delta subspecies of protein kinase C in the trigeminal sensory system of Trimeresurus flavoviridis, an infrared-sensitive snake.

We examined the expression of the protein kinase C (PKC) delta subspecies in the trigeminal sensory system of the infrared-sensitive snake Trimeresurus flavoviridis. In the trigeminal ganglion (TG), diffuse low-intensity PKC delta immunoreactivity was found in TG neurons and fibers, while intense reactions were observed mainly in medium-sized neurons, which include most of the infrared-sensitive neurons. In the brainstem, intense PKC delta immunoreactivity was present in the intermediate layer of the optic tectum of the midbrain and in the nucleus descendens lateralis n. trigemini of the medulla oblongata; these areas are related to the infrared sensory pathway. In the pit organ (the infrared receptor), PKC delta immunoreactivity was present in terminal nerve masses in the pit membrane. These findings suggest that the PKC delta subspecies is involved in the infrared sensory pathway in the trigeminal sensory system of the infrared-sensitive snake.