Effects of nociceptin/orphanin FQ and endomorphin-1 on glutamate and GABA release, intracellular [Ca2+] and cell excitability in primary cultures of rat cortical neurons.
The effects of nociceptin/orphanin FQ (N/OFQ) and endomorphin-1 (EM-1) on glutamate and GABA release, intracellular calcium, neuronal excitability and glutamate current were investigated in rat primary cortical neuronal cultures. Through their specific receptors N/OFQ and EM-1 (0.02-1 microM) inhibited the electrically evoked outflow of [3H]D-aspartate at most to -50% and that of [3H]GABA to -30%. In addition, at 1 microM, both peptides induced a decrease of the firing rate caused by electrical depolarization. N/OFQ 1-10 microM did not influence either the electrically evoked calcium influx or the glutamate-evoked currents, whereas EM-1 1 microM significantly inhibited them. Thus, in cortical neurons in culture, both N/OFQ and EM-1 inhibited the secretory process and neuronal excitability but EM-1 also affected calcium influx and cell body responsiveness to glutamate. Consequently, EM-1 appeared to dampen this excitatory signal more then N/OFQ did.
Bianchi
C
C
Department of Clinical and Experimental Medicine, Section of Pharmacology and Neuroscience Center, University of Ferrara, via Fossato di Mortara 17-19, Ferrara 44100, Italy. bnc@unife.it
Marani
L
L
Barbieri
M
M
Marino
S
S
Beani
L
L
Siniscalchi
A
A
D000200:Action Potentials / Q000187:drug effects; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D004558:Electric Stimulation; D018698:Glutamic Acid / Q000378:metabolism*; D015640:Ion Channel Gating / Q000187:drug effects; D009292:Narcotic Antagonists / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009842:Oligopeptides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D018847:Opioid Peptides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000187:drug effects; D013779:Tetrodotoxin / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*; D000097629:Nociceptin
D000701:Analgesics, Opioid; D002118:Calcium; D018698:Glutamic Acid; D009292:Narcotic Antagonists; D009842:Oligopeptides; D018847:Opioid Peptides; D011957:Receptors, Opioid; D013779:Tetrodotoxin; D014665:Vasodilator Agents; D005680:gamma-Aminobutyric Acid; D000097629:Nociceptin; C105293:endomorphin 1