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Neuropeptide Y and Peptide YY Inhibit Excitatory Synaptic Transmission in the Rat Dorsal Motor Nucleus of the Vagus
Author(s) -
Browning Kirsteen N.,
Travagli R. Alberto
Publication year - 2003
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2003.042036
Subject(s) - peptide yy , neuropeptide y receptor , excitatory postsynaptic potential , dorsal motor nucleus , yohimbine , endocrinology , medicine , chemistry , agonist , postsynaptic potential , neurotransmission , inhibitory postsynaptic potential , antagonist , neuropeptide , receptor , vagus nerve , stimulation , biology
Pancreatic polypeptides (PPs) such as neuropeptide Y (NPY) and peptide YY (PYY) exert profound, vagally mediated effects on gastrointestinal (GI) motility and secretion. Whole‐cell patch clamp recordings were made from brainstem slices containing identified GI‐projecting rat dorsal motor nucleus of the vagus (DMV) neurons to determine the mechanism of action of PPs. Electrical stimulation of nucleus tractus solitarii (NTS) induced excitatory postsynaptic currents (EPSCs) that were reduced in a concentration‐dependent manner by NPY and PYY (both at 0.1–300 n m ) in 65 % of the neurons. An increase in the paired‐pulse ratio without changes in the postsynaptic membrane input resistance or EPSC rise and decay time suggested that the effects of PPs on EPSCs were due to actions at presynaptic receptors. The Y1 and Y2 receptor selective agonists [Leu 31 ,Pro 34 ]NPY and NPY(3–36) (both at 100 n m ) mimicked the inhibition of NPY and PYY on the EPSC amplitude. The effects of 100 n m NPY, but not PYY, were antagonized partially by the Y1 receptor selective antagonist BIBP3226 (0.1 μ m ). In addition, the inhibition of the EPSC amplitude induced by NPY, but not PYY, was attenuated partially by pretreatment with the α 2 adrenoceptor antagonist yohimbine (10 μ m ), and occluded partially by the α 2 adrenoceptor agonist UK14,304 (10 μ m ) as well as by pretreatment with reserpine. Pretreatment with a combination of BIBP3226 and yohimbine almost completely antagonized the NPY‐mediated effects on EPSCs. Contrary to the inhibition of EPSCs, perfusion with PPs had no effect on the amplitude of inhibitory postsynaptic currents (IPSCs) and a minimal effect on a minority of DMV neurons. Differences in the receptor subtypes utilized and in the mechanism of action of NPY and PYY may indicate functional differences in their roles within the circuitry of the dorsal vagal complex (DVC).