|Budget Amount *help
¥6,700,000 (Direct Cost : ¥6,700,000)
Fiscal Year 1997 : ¥2,800,000 (Direct Cost : ¥2,800,000)
Fiscal Year 1996 : ¥3,900,000 (Direct Cost : ¥3,900,000)
Immunohistochemical localization of GABAB-receptors was demonstrated in the rat brain using a monoclonal antibody (GB-1) raised against purified GABAB-receptor. Immunoreactive staining for GABAB-receptors was localized in certain neuronal populations which were distributed widely throughout the brain and spinal cord of adult rat. No glial cells were stained positively. Positive neurons possessed immunoreactin products mainly in the cell membrane and occasionally in the cytoplasm. In the forebrain, positive neurons were observed in the cerebral cortex, hippocampus, amygdaloid nuclei, pyriform cortex, thalamic nuclei, hypothalamic nuclei, striatum and globus pallidus. In the hindbrain, positive neurons were located in the lateral geniculate body, mesencephalic reticular formation, central gray of the cerebral aqueduct, superior collculus, inferior colliculus, substantia nigra, parabrachial nuclei, dorsal tegmental nucleus, locus coeruleus, pontine reticular nucleus, cerebellum, deep cere
bellar nuclei, trigeminal nucleus of the spinal tract, inferior olive, cochlear nucleus and nucleus of the trapezoid body. In the spinal cord, positive motoneurons were mostly stained intensely, and less intensely stained neurons were also found in the dorsal horn and around the central canal. Double immunostaining indicated that such positive cells for GABAB-receptors often co-possessed GABA in some cases.
Our further study in developing rats indicated that positive staining for GABAB-receptors was first seen in the spinal cord and the diencephalon. This pattern of ontogenic development appears coincide, at least partly, with the expression of GABA in neuronal structures.
When the distribution pattern of GABAB-receptors was compared with that of GABAA-receptors in the nucleus tractus solitarius, most subregions of the nucleus appeared to be occupied preferentially by either one of GABA-receptors. The detail of the results will be presented and discussed in relation with their roles in physiological function. Less