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DISTRIBUTION OF TAURINE-LIKE IMMUNOREACTIVE CELLS IN THE RAT BRAIN

MASAKO ITO*, MASAMI YOSHIDA, NOBUYUKI KARASAWA, MASAO SAKAI* and IKUKO NAGATSU Department of Anatomy, School of Medicine, Fujita-Gakuen Health University, Toyoake, Aichi 470-11, Japan

One of the neuroactive amino acids, taurine (Tau), is present in the brain in high concentration, but few data are available as to its cellular localization in the central nervous system (CNS). Antibody directed to Tau was applied to visualize central Tau-containing structures in this study.

Antiserum was raised in rabbits immunized with Tau coupled to bovine serum albumin by glutaraldehyde (GA). The sera were purified on formyl cellulofine- Tau column. Specificity was checked by both enzyme-linked immunosorbent assay and the nitrocellulose paper immunoblot test. The purified sera showed specific reactions towards Tau immobilized in a microtiter plate or on nitrocellulose paper (amino acids-GA-polylysine as antigen), but did not cross-react significantly with GABA (0.4%), Glu, Asp, Gly, Gln, Pro, Cys,@-Ala and cysteic acid ( .... 0%).

Immunohistochemical examination revealed Tau-immunoreactive neuronal perikarya in the following regions: Olfactory bulb (some periglomerular cells and granule cells), nucleus caudatus-putamen, n. accumbens, lateral septal area, piriform cortex, hippocampal dentate gyrus and cerebellar cortex (Purkinje cells). Many Tau-labelled axons and dots were found in the white matter and deep cerebellar nuclei. Ultrastructural study showed that Tau-reaction was distributed throughout the cell matrix of soma, dendrite and axon of Purkinje cells. Cerebellar nuclear neurons were found to receive Gray type II synaptic contact with Tau-labelled terminals. Tau-labelled glial cells also distributed evenly in CNS.

From the present immunohistochemical study, it is evident that Tau or Tau-like immunoreactivity is localized in neuronal structures of discreate regions of the CNS.

PRODUCTION AND CHARACTERIZATION OF ANTIBODY AGAINST TAURINE AND ITS IMMUNOHISTOCHEMICAL APPLICATION IN THE RAT BRAIN

HIROSHI KIMURA l, YASUNOBU TOMIDA * l , TUNEICHI HASHIMOTO .2 and KINYA KURIYAMA 2, Dept. Anat., Shiga Univ. Med. Sci., Otsu 520-21, Japan I and Dept. Pharmacol., Kyoto Pref. Univ. Med., Kyoto 602, Japan 2

Taurine, one of the most ubiquitous and abundant amino acids in the body, has been shown to be physio logical ly act ive on neurons in the central nervous system. L i t t l e is known, however, about i ts anatomical d ist r ibut ion and c e l l u l a r local izat ion in the brain. In the present study, taurine-containing structures have been examined immunohistochemically using ant isera raised against taurine by immunizing rabbits with taurine coupled to a protein carr ier as an antigen. The s p e c i f i c i t y study by enzyme-linked immunoassay indicated that the best of the ant isera showed less than O.5Z c r o s s r e a c t i v i t y with various compounds, inc luding several taur ine de l ivat ives, other sulfur-containing amino acids, and gamma-aminobutyric acid (GABA).

When the antiserum was used in immunohistochemistry, taur ine- l ike immunoreactivity (TLI) was observed in both neuronal and g l i a l components in the rat brain. Numerous posi t ive g l i a ] ce l l s with TLI were distributed almost evenly throughout the brain. On the other hand, posi t ive neuronal somata with TLI were loca l i zed in cer ta in brain regions such as the l a t e r a l septal nucleus, striatum, o l factory bulb and cerebel lar Purkinje neurons. In addition, dot - l i ke struc- tures with TLI, probably indicating nerve terminals, were densely packed in a l l deep cerebel lar nuclei inc luding the nucleus v e s t i b u l a r i s l a te ra l i s . Immunoelectron microscopic examination demonstrated that the deep cerebel lar nuclei contained nerve terminals with TLI that often made axo-somatic synapses with large ce l l s in the nuclei. The TLI in the terminals were found in both synaptic vesicles and thei r surrounding axoplasm.

The presence of TLI in the Purkinje ce l l s projecting to the deep cerebel lar nuclei is par- t i c u l a r l y interesting, because the projection pathway has been well known to u t i l i z e GABA, an i n h i b i t o r y neurotransmit ter . To study the possible coexistence of taur ine withGABA in th is pathway, the contents of both amino acids in the deep cerebel lar nuclei of cerebellar-ablated rats were measured by high performance l iquid chromatography. The resul t c lea r l y indicated that taurine and GABA were concomitantly decreased in the nuclei of the lesioned side. The functional significance of taurine in this neuronal c i rcu i t as well as in other brain regions remains to be elucidated.