Effect of subcutaneous injection of morphine on activity of neurons in the nucleus cuneiformis of rat
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Date
2008-12-31
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Brieflands
Abstract
Background: The similarities between periaqueductal gray matter and the nucleus cuneiformis in
both ultrastructural and functional levels suggest that this nucleus may play an important role in
the morphine-induced analgesia. This study was designed to determine neuronal activity and
responsiveness to peripheral morphine administration in the nucleus coneiformis of rat.
Materials and Methods: In this study, neural activity of cuneiform neurons in response to
peripheral administration of morphine was recorded by extracellular single unit recording
technique. Firing rate of neurons was recorded in four groups: intact group (n=19) to determine
the spontaneous (baseline) activity, saline group (n=20), morphine group (n=39) and morphine +
naloxone group (n=12), before and after drug administration.
Results: Our findings showed that the firing rate in majority of cuneiform neurons decreased
after morphine (3.8 mg/kg; SC) administration. Activity of neurons (n=39) in the cuneiform neurons
was reduced significantly (P