Selective inactivation of opioid receptors in rat hippocampus demonstrates that dynorphin-A and -B may act on mu-receptors in the CA1 region.
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.
Chavkin
C
C
Henriksen
S J
SJ
Siggins
G R
GR
Bloom
F E
FE
D000818:Animals; D004399:Dynorphins / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004723:Endorphins / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects*; D066298:In Vitro Techniques; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects*; D017450:Receptors, Opioid, mu
D004723:Endorphins; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D009271:Naltrexone; C024524:beta-funaltrexamine; D004399:Dynorphins; C036200:rimorphin