Localization of GABA_B receptor in the central endogenous pain control system of rats

AIM To examine the distribution of gamma aminobutyric acid B receptor (GABA BR) in the central endogenous pain control system of the rat. METHODS Immunohistochemical staining technique was used with specific antibody against GABA BR. RESULTS Densely stained GABA BR like immunoreactive neuronal cell bodies were observed in the dorsal raphe nucleus (DR), median raphe nucleus (MnR), pontine raphe nucleus (PnR), nucleus raphe magnus (NRM), nucleus raphe obscurus (ROb) and nucleus raphe pallidus (RPa). Additionally, GABA BR like immunoreactive neuronal cell bodies were also found in the midbrain periaqueductal gray (PAG) and gigantocellular reticular nucleus pars α (GiA). GABA BR like immunoreactive fibers and terminals were encountered in those nuclei as well. CONCLUSION Present results indicate that GABA BR like immunoreactive neuronal cell bodies, fibers and terminals are located in the central endogenous pain control system. They might be involved in the regulatory effects upon this system.