LOCALIZATION OF 5-HT2A RECEPTOR IN RAT CEREBRAL-CORTEX AND OLFACTORY SYSTEM REVEALED BY IMMUNOHISTOCHEMISTRY USING 2 ANTIBODIES RAISED IN RABBIT AND CHICKEN

Serotonin 2A receptor (5-HT2A receptor) is widely distributed in the c entral nervous system, and has been suggested to be involved in a vari ety of behavioral conditions and neuropsychiatric disorders. Two polyc lonal antibodies were raised against the N-terminus peptide of rat 5-H T2A receptor in chickens (5-HT2A-N) and a glutathione S-transferase fu sion protein that contained the C-terminus of the mouse 5-HT2A recepto r in rabbits (5-HT2A-C). Affinity-purified 5-HT2A-N and -C antibodies reacted strongly with a single band of 77-78 kDa in postsynaptic densi ty proteins prepared from the rat cortex. The distribution pattern of immunoreactive structures in the rat brain was virtually the same for the two antibodies. The highest levels of immunoreactivity were observ ed in the olfactory bulb, neocortex, claustrum, piriform cortex, mamil lary bodies, pontine nuclei, red nucleus and cranial motor nuclei. In the olfactory bulb, mitral cells were intensely labeled. In the neocor tex, many immunoreactive neurons were found in layers II-VI. In layer IV of the neocortex, strong neuropil labeling was observed. In a doubl e-labeling study using chicken 5-HT2A-N and rabbit anti-glial fibrilla ry acidic protein (GFAP) antibody, a considerable number of GFAP posit ive cells also showed 5-HT2A immunoreactivity. By using an immunoelect ron microscopic technique, 5-HT2A receptor immunoreaction was shown to be localized just beneath the postsynaptic membrane thickening of asy mmetric synapses. (C) 1998 Elsevier Science B.V.