2723717

GABA- and glutamate-mediated synaptic potentials in rat dorsal raphe neurons in vitro.

Article date: 1989/4/1

PubMed ID: 2723717

Journal name: Journal of neurophysiology (ISSN: 0022-3077)

ABSTRACT

1. Synaptic potentials were recorded with intracellular electrodes from rat dorsal raphe neurons in a slice preparation. 2. Synaptic potentials were evoked by applying electrical pulses to bipolar stimulating electrodes positioned immediately dorsal to the raphe nucleus; these arose after a latency of 0.5-5 ms and had a duration of 20-200 ms. 3. The synaptic potential was biphasic (at the resting potential) when the recording electrodes contained potassium citrate; a depolarization was followed by a hyperpolarization. The hyperpolarization reversed in polarity at -70 mV and was blocked by bicuculline. 4. The depolarizing synaptic potential was reduced to 50-90% of control by kynurenate (1-2 mM) or 6-cyano-2,3-dihydroxy-7-nitro-quinoxaline (CNQX) (10 microM) and increased in amplitude and duration by magnesium-free solution. 5. In magnesium-free solutions (with CNQX), the depolarizing synaptic potential was blocked by DL-2-amino-5-phosphonovaleric acid (APV, 50 microM). APV also blocked depolarization caused by adding N-methyl-D-aspartate (NMDA) to the superfusion solution. 6. The results indicate that raphe neurons display two synaptic potentials having a duration of 150-200 ms: one that is mediated by GABA and a second that is due to an excitatory amino acid. The component mediated by an excitatory amino acid involves, in part, a receptor of the NMDA type.

Author List: Pan Z Z, Williams J T

Publication Types: Journal Article; Research Support, U.S. Gov't, P.H.S.

Substances mentioned in the article: Glutamates; Picrotoxin; Muscimol; gamma-Aminobutyric Acid; Bicuculline;

Mesh terms: Animals; Bicuculline/pharmacology; Evoked Potentials/drug effects; Glutamates/pharmacology; In Vitro Techniques; Membranes/physiology; Muscimol/pharmacology; Picrotoxin/pharmacology; Raphe Nuclei/cytology; Rats; Synapses/physiology; gamma-Aminobutyric Acid/pharmacology;

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