Upregulation of galanin binding sites and GalR1 mRNA levels in the mouse locus coeruleus following chronic morphine treatments and precipitated morphine withdrawal
V. Zachariou et al., Upregulation of galanin binding sites and GalR1 mRNA levels in the mouse locus coeruleus following chronic morphine treatments and precipitated morphine withdrawal, NEUROPSYCH, 23(2), 2000, pp. 127-137
The neuropeptide galanin and its receptors are expressed in the locus coeru
leus (LC), a brain circa associated with drug dependence and withdrawal. Al
though galanin peptide mRNA levels do not change during withdrawal, it is n
ot known whether galanin receptor levels are regulated following opiate wit
hdrawal. This study demonstrates that galanin binding ill the LC is upregul
ated by chronic-intermittent morphine administration or by precipitated wit
hdrawal, but not by acute morphine treatment, suggesting that increased act
ivity in the LC may be able to regulate galanin binding sites. Moreover, th
e increase in galanin binding sites seems to be caused by increased transcr
iption or stabilization of the galanin receptor 1 (GalR1) gene, because the
re is a dramatic increase ii? mRNA levels following withdrawal in the LC. I
t is, therefore, possible that the increase in GalR1 could be an adaptive m
echanism that leads to regulation of cAMP levels and possibly firing rate o
f LC neurons. (C) 2000 American College of Neuropsychopharmacology. Publish
ed by Elsevier Science Inc. All rights reserved.