| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1988: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1987: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
Adenosine has been implicated as a modulator of neural transmission, in addition to its ubiquitous involvement in intermediary metabolism. In both central and peripheral tissues, the localization of adenosine receptors and associated adenylate cyclases by anatomical and pharmacological means has provided some clues about sites of action of this substance. An accumulation of electrophysiological studies has shown that adenosine is an inhibitory neurotransmitter in the central nervous system.
Our interest has centered on the identification of markers which would allow the anatomical visualization of adenosinergic neurons. We chose to investigate the possibility that the enzymes responsible for synthesis or degradation of adenosine may be markers for neurons in which adenosine serves a neuromodulatory function. Specific antisera against adenosine, S-adenosyl homocysteinase (SAH)(synthesizing enzyme) and adenosine deaminase (ADA)(degrading enzyme) were raised in rabbits. To date, a relative
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ly restricted distribution of neurons was investigated. The latter neurons showed rather ubiquitous distribution in the brain compared to ADA containing neurons.
For further anatomical analysis, we chose retino-collicular pathway as a model, because abundant adenosine receptors are identified in the superficial superior colliculus and numerous ADA-containing neurons are distributed in the same layer (E. Senba et al, 1987; J.J.Miguell et a., 1989). These ADA immunoreactive neurons were shown to project to the postero-lateral nucleus of thalamus (J.J.Miguell et al,1988). In the retina, adenosine-IR and/or SAH-IR neurons were located in the ganglion cell layer and these neurons were shown to be ganglion cells (Senba et al, in preparation). ADA-containing neurons were also observed in the same layer, but these neurons were demonstrated to be displaced amacrine cells (E.Saenba et al.,1986) Immunoelectron microscopy combined with degeneration method revealed that dendrites of these ADA contianing neurons receive direct axonal inputs from the retina (J.J.Miguell, in preparation). Less
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