Effects of DAGO on the rodent hippocampal evoked potentials using different perfusion solutions.
Opioid receptor agonists exert excitatory effects in the hippocampus by inhibiting GABA release. We report that the mu-opioid agonist, DAGO, increases the amplitude of the population spikes (PS) measured in the stratum pyramidale of the CA1 cell layer in mouse and rat hippocampal slices perfused with an artificial cerebrospinal fluid (ACSF), but not when perfused in Krebs solution. The GABAA agonist, 3-APS, induces inhibitory responses when perfused in either ACSF or Krebs. Also, the field excitatory postsynaptic potentials (EPSP) measured on stratum radiatum do not differ when the slice is perfused with either ACSF or Krebs. The increase in the amplitude of the PS induced by DAGO is not obtained when perfused in a modified. ACSF whose concentration of MgSO4 was lowered to its concentration in the Krebs solution (from 2.4 mM to 1.2 mM). Thus, changes in the concentration of MgSO4 seem to be responsible for the different responses induced by DAGO.
SanMartín
S
S
Departamento de Medicina, Facultad de Medicina, Oviedo, Spain.
Menéndez
L
L
Gutiérrez
M
M
Hidalgo
A
A
Baamonde
A
A
D000700:Analgesics / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D018755:GABA Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology*; D066298:In Vitro Techniques; D007552:Isotonic Solutions / Q000494:pharmacology*; D008278:Magnesium Sulfate / Q000494:pharmacology; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D013654:Taurine / Q000031:analogs & derivatives / Q000494:pharmacology
D000700:Analgesics; D000701:Analgesics, Opioid; D018755:GABA Agonists; D007552:Isotonic Solutions; C051865:Krebs-Ringer solution; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D013654:Taurine; C001355:tramiprosate; D008278:Magnesium Sulfate