Abstract
The objective of the study was to investigate the regulatory actions of
unacylated ghrelin (UAG) on glucose-sensitive (GS) neurons and glycolipid
metabolism in the lateral hypothalamus area (LHA) and its involvement with
orexin-A-immunopositive neurons. The effects of UAG administered into the
LHA on GS neurons discharges and glycolipid metabolism were detected by
single neuron discharge recording, biochemical index analysis and
quantitative real-time PCR; the level of c-fos protein in
orexin-A-immunopositive neurons was observed using immunofluorescence
staining. UAG microinjected into the LHA activated glucose-inhibited
neurons, which were partially blocked by pre-administration of anti-orexin-A
antibody in the LHA. Furthermore, UAG microinjected into the LHA
significantly reduced serum triglycerides (TG), total cholesterol,
low-density lipoprotein cholesterol, blood glucose, insulin and hepatic TG
levels, while elevated serum high-density lipoprotein cholesterol levels.
UAG elevated the mRNA expression of carnitine palmitoyltransferase-1 and
reduced the mRNA expression of acetyl-CoA carboxylase-1 in the liver. The
above-mentioned effects of UAG were partially blocked by pre-administration
of anti-orexin-A antibody. The expressions of orexin-A and c-fos were
observed in the LHA. After UAG injection into the LHA, some neurons showed
double labeling, and the percentage of double-labeled orexin-A/c-fos
neurons in orexin-A-immunopositive neurons increased significantly. UAG in
the LHA regulates glycolipid metabolism by activating
orexin-A-immunopositive neurons in the LHA.
Key words
unacylated ghrelin - lateral hypothalamus area - glycolipid metabolism - glucose-sensitive neurons - orexin-A-immunopositive neurons
