Muscarinic and adrenergic neurotransmission in the CA1 area of rat hippocampus.

E N GONZALEZ; M V OBERHOLZER; E KORNISIUK; D A JERUSALINSKY

Huerta Grande

Congreso; XXVI Congreso Anual de SAN; 2011

SAN-TAN

Muscarinic and adrenergic neurotransmission in the CA1 area of rat hippocampus. González, N.; Oberholzer, V.; Kornisiuk, E.; Cerveñansky, C.; Jerusalinsky, D. XXVI Congreso Anual de la SAN, Córdoba, Argentina. Octubre de 2011.   Poster Number 234 | Session 3   "Muscarinic and adrenergic neurotransmission in the CA1 area of rat hippocampus" Nicolás González3, María Victoria Oberholzer3, Edgar Kornisiuk3, Carlos Cerveñansky2, Diana Jerusalinsky 3,1 1CBC, UBA, Argentina, 2Insitut Pasteur, Uruguay, 3Instituto de Biología Celular y Neurociencia, UBA-CONICET, Argentina enicogon@gmail.com   Adrenergic and muscarinic neurotransmission in rat hippocampus are involved in synaptic plasticity. We have shown that muscarinic toxin 1 (MT1) from Mamba snake venom (an M1 muscarinic receptor agonist and M4 antagonist) also binds to hippocampal α-adrenergic (α-1) receptors. In radioligand binding assays in rat hippocampal membranes, MT1 inhibited the binding of the muscarinic ligand 3H-N-methylscopolamine (3H-NMS, Ki=180±7 nM) and that of the α-1 antagonist 3H-prazosin (3H-PRZ, Ki=83±3 nM), with maximal inhibition of 49±5% and 34±4%, respectively. Furthermore, PRZ inhibited 3H-NMS binding (Ki=5.1±1.2 µM). Further assays are carried out to estimate inhibition parameters for the α-1 agonist phenylephrine (PE) on 3H-PRZ and 3H-NMS binding. We registered field excitatory postsynaptic potentials (fEPSPs) in CA1 area of rat hippocampal fresh slices. Perfusion with MT1, PRZ and PE modified fEPSPs. MT1 (1µM) and PRZ (10µM) significantly increased fEPSP (41.4±5.2%, n=5; 15.8±3.2%, n=6, respectively); while PE (10µM) decreased fEPSP (23.0±9.0%; n=4). These indicate that activation of α-a receptors inhibits basal transmission at CA1 synapse. Co-perfusion of MT1+PRZ and MT1+PE would help to discriminate MT1 action on α-1 receptors.