Gj. Taborsky et al., CANINE LIVER RELEASES NEUROPEPTIDE-Y DURING SYMPATHETIC-NERVE STIMULATION, The American journal of physiology, 266(5), 1994, pp. 50000804-50000812
To determine whether the liver or gut releases neuropeptide Y (NPY) fr
om their sympathetic nerves, we performed bilateral thoracic sympathet
ic nerve stimulation (BTSNS) in halothane-anesthetized dogs and calcul
ated gut and liver NPY spillover. BTSNS markedly increased hepatic NPY
spillover (Delta = +32 +/- ng/min) and arterial NPY concentration (De
lta = +220 +/- 56 pg/ml), despite no effect on gut NPY spillover (Delt
a = +8 r 7 ng/min). To determine the liver's contribution to this incr
ease of circulating NPY, hepatic nerves were selectively stimulated (H
NS). Liver NPY spillover increased markedly (Delta = -114 +/- 42 ng/mi
n, P < 0.025) during HNS, causing a large increase of arterial NPY (De
lta = +586 +/- 237 pg/ml, P < 0.025). Using this ratio of liver spillo
ver to arterial increments of NPY, we calculated that the liver makes
a major contribution (70%) to circulating NPY levels during BTSNS. The
predominant form of canine NPY coeluted with synthetic [Met(17)]NPY a
nd the minor form of canine NPY coeluted with the oxidized form of [Me
t(17)]NPY on high-performance liquid chromatography. We therefore conc
lude that dog NPY is likely [Met(17)]NPY and that the liver, rather th
an the gut, is a major source of circulating NPY during sympathetic ne
rve stimulation and perhaps stress.