Up-regulation of orexigenic and down-regulation of anorexigenic neuropeptide gene expression in rat hypothalamus after partial lipectomy

• Removal of adipose tissue (lipectomy) in rats causes a decrease in serum leptin concentrations, and an increase in food intake and standard growth rate.
• Lipectomy increases hypothalamic orexigenic neuropeptide gene expression.
• Lipectomy decreases hypothalamic anorexigenic neuropeptide gene expression.

Leptin down-regulates orexigenic and up-regulates anorexigenic neuropeptide gene expression in hypothalamus. Surgical removal of adipose tissue leads to decrease in circulating leptin concentrations in rats. In the present study, we tested: (a) regulation of neuropeptide gene expression in hypothalamus, (b) food intake, and (c) standard growth rate after removal of adipose tissue in rats. Partial lipectomy caused an approximately 10-fold reduction of subcutaneous, retroperitoneal and epididymal adipose tissue weight (at the end of experiments adipose tissue weight was 1.5 ± 0.9 in lipectomy and 15 ± 3.9 g in control rats; statistically significant). Compared to control rats, the animals subjected to lipectomy presented increased food intake, standard growth rate, and decreased serum leptin concentrations (2.6 ± 0.8 vs. 3.7 ± 1.2 ng/mL in the controls, statistically significant). These changes were associated with approximately twofold increase in neuropeptide Y, threefold increase in agouti-related peptide (orexigenic neuropeptides) and about 50% decrease in pro-opiomelanocortin and cocaine–amphetamine-regulated transcript peptide (anorexigenic neuropeptides) mRNA levels in the hypothalamus. These results suggest that partial lipectomy, leading to a decrease in circulating leptin concentrations, may exert an effect on hypothalamic orexigenic and anorexigenic neuropeptide gene expression, and consequently modulate food intake and standard growth rate in rats.

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