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Inhibitory effects of NPY on ganglionic transmission in myenteric neurones of the guinea‐pig descending colon
Author(s) -
Kirsteen N. Browning,
Lees Gm
Publication year - 2000
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1046/j.1365-2982.2000.00178.x
Subject(s) - guinea pig , inhibitory postsynaptic potential , descending colon , myenteric plexus , distal colon , biology , transmission (telecommunications) , enteric nervous system , neuroscience , immunohistochemistry , medicine , endocrinology , immunology , rectum , computer science , telecommunications
Intracellular recordings were made from myenteric neurones of the guinea‐pig descending colon. Neuropeptide Y (NPY) and related pancreatic polypeptides were applied by superfusion and the effects upon the amplitude of fast excitatory synaptic potentials (ESPs) and the ratio of paired fast ESPs evoked by stimulation of internodal fibre tracts were noted. NPY produced a concentration‐dependent inhibition in fast ESP amplitude in the majority of neurones (17/21) with a calculated IC 50 value of 7 nM; in some neurones this inhibition was mediated via the local release of noradrenaline. Peptide YY (PYY) (eight out of 11 neurones; IC 50 = 1 nM), NPY(3–36) (three out of three neurones) and [Leu 31 , Pro 34 ]NPY (four out of five neurones) also decreased the amplitude of fast ESPs. The effects of two or more pancreatic polypeptides or analogues on fast synaptic transmission were compared directly in six neurones; the apparent relative potency of agonists suggested the involvement of Y 2 ‐receptors and at least one other Y‐receptor type. In the absence of any direct postsynaptic effects of pancreatic polypeptides on the active or passive properties of myenteric neurones, or on their sensitivity to ionophoretically applied acetylcholine, inhibition of fast ganglionic transmission was presumed to be presynaptic in origin. It is concluded that, in addition to their previously described depressant actions on neuro‐effector transmission to colonic smooth muscle, pancreatic polypeptides can exert powerful inhibitory effects on myenteric neurones of the descending colon.