The M1 antagonist pirenzepine suppresses heterosynaptic STD in the CA1 region.
The effect of the muscarinic M1 and M2 antagonists (pirenzepine and gallamine) on heterosynaptic short-term depression (HSTD) of the CA1 population spike was studied in rat hippocampal slices. HSTD was evoked by a train of 30-50 pulses at 5 Hz (theta-like stimulation; TLS) delivered to the stratum oriens. Bath-applied pirenzepine (10(-6)-3 x 10(-6) M) significantly suppressed the magnitude of HSTD in the tested radiatum input (56 +/- 26% of control, p < 0.05). In contrast, gallamine (10(-6)-10(-5) M) did not suppress HSTD (102 +/- 7%). An enhancement of HSTD during application of eserine was also antagonized by pirenzepine (71 +/- 18%, p < 0.01), but not by gallamine (152 +/- 85%). These data suggest that acetylcholine synaptically released during TLS of the stratum oriens significantly contributes to HSTD in the CA1 region by activation of the M1 muscarinic receptor subtype.
Kozhemyakin
M B
MB
Brain Research Institute, Moscow, Russia.
Kleschevnikov
A M
AM
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D003864:Depression, Chemical; D005071:Evoked Potentials / Q000187:drug effects; D005703:Gallamine Triethiodide / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009473:Neuronal Plasticity / Q000187:drug effects*; D010890:Pirenzepine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000378:metabolism; D013569:Synapses / Q000187:drug effects* / Q000378:metabolism; D013826:Theta Rhythm
D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D010890:Pirenzepine; D000109:Acetylcholine; D005703:Gallamine Triethiodide