The Role of GABAB Receptors in Morphine Self‑Administration

Abstract

There is only little information about the effects of GABA receptors agonist and antagonist on morphine self‑administration. Present study was designed to assess role of GABAB receptors in the regulation of morphine‑reinforced self‑administration. This study was performed in four groups of rats: (1) Saline group, which received saline in the self‑administration session. (2) Morphine group, which received morphine in saline solution in the self‑administration session. (3) Baclofen + Morphine group, which received both baclofen 20 min before self‑ administration test and morphine in the self‑administration session. (4) Phaclofen + Morphine group, which received both phaclofen 20 min before self‑ administration test and morphine in the self‑administration session. The number of lever pressing and self‑infusion were recorded. Morphine significantly increased the number of active lever pressing dose dependently in self‑administration session in comparative with saline group. Administration of baclofen, 20 min before morphine self‑administration produced significant decrease in the initiation of morphine self‑administration during all session. Conversely, pre‑treatment of phaclofen increased the number of active lever pressing and self‑infusion in this test. Our results indicated a short‑term treatment by baclofen, reduced morphine‑maintenance response in a dose‑dependent manner, suggesting that GABAB receptor agonists could be useful for reversing the neuroadaptations related to opiates.

Keywords: Baclofen, morphine addiction, phaclofen, self‑administration