Selective inactivation of opioid receptors in rat hippocampus demonstrates that dynorphin-a and dynorphin-b may act on mu-receptors in the ca1 region

Academic Article
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publication date

  • 1985

abstract

  • Dynorphin-A1-17 and dynorphin-B increased the evoked response of hippocampal CA1 pyramidal cells, as did other opioids tested. Treatment of the hippocampal slice with beta-funaltrexamine, a mu-receptor selective antagonist, blocked the effects of normorphine, dynorphin-A and dynorphin-B, but did not change the response to D-Ala2, D-Leu5-enkephalin. The low potency of kappa selective agonists and the antagonism by beta-funaltrexamine of the dynorphins' effect indicate that kappa-opioid receptors may not be involved in these observed responses. Our data suggest that both mu- and delta-receptors are functionally represented and provide evidence that the dynorphins or their derivatives may also be agonists at the mu-receptor.