Distinct properties of carbachol- and DHPG-induced network oscillations in hippocampal slices.
The aim of this study was to compare and contrast the properties of gamma oscillations induced by activation of muscarinic acetylcholine or metabotropic glutamate receptors in the CA3 region of rat hippocampal slices. Both carbachol and the group I metabotropic glutamate receptor agonist, (RS)-3,5-dihydroxyphenylglycine (DHPG), induced network oscillations in the gamma-frequency range (30-100 Hz). The M1 muscarinic receptor antagonist, pirenzepine, blocked carbachol-, but enhanced DHPG-induced oscillations, whereas LY 341495, an antagonist at metabotropic glutamate receptors, abolished DHPG-, but left carbachol-induced oscillations unchanged. There were significant differences in the peak frequency, maximal power, and spectral width of the two oscillations. Pharmacological experiments showed that both types of oscillation depend on fast excitatory and inhibitory synaptic transmission. Interestingly, activation of neurokinin-1 receptors by substance P fragment or enhancement of inhibitory synaptic currents by the benzodiazepine ligand, zolpidem, boosted DHPG-, but reduced the power of carbachol-induced oscillations. These results suggest that, although carbachol and DHPG might activate similar conductances in individual pyramidal cells, the oscillations they induce in slices involve different network mechanisms, most likely by recruiting distinct types of GABAergic interneuron.
Department of Cellular and Network Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, 1083 Budapest, Hungary.
J
J
Pálhalmi
O
O
Paulsen
T F
TF
Freund
N
N
Hájos
D000200:Action Potentials / Q000187:drug effects*; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001569:Benzodiazepines / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D018679:Cholinergic Agonists / Q000494:pharmacology*; D003959:Diamines / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D018727:Muscarinic Antagonists / Q000494:pharmacology; D010890:Pirenzepine / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists*; D013057:Spectrum Analysis; D013373:Substance P / Q000494:pharmacology; D014966:Xanthenes / Q000494:pharmacology; D000077334:Zolpidem
D000596:Amino Acids; D018679:Cholinergic Agonists; D003959:Diamines; D018691:Excitatory Amino Acid Antagonists; D018755:GABA Agonists; D018756:GABA Antagonists; C114624:LY 341495; D018727:Muscarinic Antagonists; D011725:Pyridines; D018094:Receptors, Metabotropic Glutamate; D014966:Xanthenes; C104077:metabotropic glutamate receptor type 1; D001569:Benzodiazepines; C079692:GYKI 53655; D013373:Substance P; D010890:Pirenzepine; D008734:Methoxyhydroxyphenylglycol; D000077334:Zolpidem; D002217:Carbachol; C054938:methoctramine; C010117:3,4-dihydroxyphenylglycol; D001640:Bicuculline