CONICET | Buscador de Institutos y Recursos Humanos

Clathrin-mediated endocytosis (CME) is important in the Central Nervous System for maintainance of membranous homeostasis at nerve terminals. Ketamine (KET) is a drug used as an anesthetic but with an increasing use in the treatment of acute and chronic pain, due to its action as NMDA receptor antagonist. We wondered if the drug affects the expression and cycle of coat proteins involved in CME in the rat accumbens (NA) and if it also induces alterations in exocytic machinery. Adult rats were treated with subanesthetic doses of KET for 15 min, 3 h or 24 h. After that, they were killed by decapitation, and the NA were dissected, homogenized and centrifuged. The post-nuclear supernatants were newly centrifuged at 20,000 x g to obtain membranous and soluble fractions. The coat protein AP-2 was analysed in both fractions by Western blot. It was observed that AP-2 bound to membranes is decrased with respect to controls. In order to determine whether KET affects exocytosis, other rats were decapited after treatment and their NA were cut in sections of 200 m with a tissue cutter McIIwain. Sections were pre-incubated with Krebs-Ringer-Bicarbonate-Glucose solution (KRBG) containing [3H]-dopamine at 37 ºC with 5% CO2 for 30 min, and then they were perfused with KRBG for 60 min at 0,5 ml/min flow rate and fractions were collected from control and experimental NA (basal release). Subsequently, the samples were perfused with nonspecific depolarizing agent (28 mM K+) and the fractions were collected. The release of [3H]dopamine under these conditions was measured and referred with respect to baseline values. It was noted that release of dopamine decreased from 15 min of KET treatment. After 24 h , this effect was mitigated. These results could suggest an acute effect of KET affects on endocytic/exocytic pathway in the nucleus accumbens.

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