Modulatory effects of adenosine upon the transmitter release in the hippocampal slice preparation of rats.
In the hippocampal slice preparation of rats, preloaded with 3H-glutamate a local perfusion technique was used in order to measure the labelled transmitter output. The electrical receptive stimulation of the Schaffer collateral-commissural projections resulted in a detectable 3H-glutamate release which was significantly increased in the presence of 4-aminopyridine (4-AP). Exogenous adenosine and its analogue L-PIA induced a slight unsignificant reduction of the release while in the presence of 4-AP the release was almost completely blocked. Adding adenosine deaminase (ADA) did not change the normal transmitter release while in the presence of 4-AP the elimination of the endogenous adenosine brought about a significantly higher 3H-glutamate output. It is concluded that the adenosine-induced presynaptic inhibition of the transmitter release could be a significant mechanism under conditions in which the synaptic activity is abnormally high. This effect seems to be mediated via the A1 adenosine receptor since the D-PIA isomer application has no significant inhibitory effects.
D015761:4-Aminopyridine; D000241:Adenosine / Q000494:pharmacology*; D000243:Adenosine Deaminase / Q000494:pharmacology; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D018377:Neurotransmitter Agents / Q000378:metabolism*; D010660:Phenylisopropyladenosine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011983:Receptors, Purinergic / Q000502:physiology
D000631:Aminopyridines; D005971:Glutamates; D018377:Neurotransmitter Agents; D011983:Receptors, Purinergic; D010660:Phenylisopropyladenosine; D018698:Glutamic Acid; D015761:4-Aminopyridine; D000243:Adenosine Deaminase; D000241:Adenosine