Thyrotropin-releasing hormone-like immunoreactive neurons in rabbit medulla oblongata

Thyrotropin-releasing hormone-like immunoreactive (TRH-LI) neuronal cell bodies and processes were identified by using the peroxidase-antiperoxidase method in the medullar oblongata of rabbits. TRH-LI cell bodies were mainly distributed in the ventral medulla (paraolivary and parapyramidal regions), and caudal raphe nuclei (nucleus raphe obscurus and nucleus raphe pallidus). TRH-LI processes with varicosities were densely distributed in the solitary nucleus, dorsal motor nucleus of the vagus nerve and area postrema. TRH-LI processes appeared to be in contact with unlabelled cell bodies in the dorsal motor nucleus of the vagus nerve.