Aims/hypothesis: Vaspin (visceral adipose tissue-derived serpin) was first identified as an adipokine in a rat model of type 2 diabetes, in which it is predominantly secreted from visceral adipose tissue. Serum concentrations of vaspin show a food intake-related diurnal variation. We therefore tested the hypothesis that vaspin plays a role in the regulation of food intake.
Methods: Vaspin levels in the hypothalamus and human stomach were determined by western blotting. The cerebrospinal fluid concentration of vaspin was measured in five healthy volunteers using an ELISA. Fed 11-week-old female db/db mice were given intraperitoneal injections of 1 mg/kg body weight of vaspin (n = 6) or saline (n = 6) on experimental days 1, 3 and 4. Changes in food intake and fed plasma glucose concentrations were determined after one intracerebroventricular administration of either 1 μg vaspin or artificial cerebrospinal fluid into 11-week-old female db/db (n = 8) and C57BL/6 mice (n = 8) up to 6 days after injection.
Results: We detected vaspin in the hypothalamus of db/db and C57BL/6 mice and in the cerebrospinal fluid of healthy individuals. Both peripheral and central vaspin administration decrease food intake in obese db/db and lean C57BL/6 mice. In db/db mice, vaspin treatment is associated with sustained glucose-lowering effects for at least 6 days after injection. In addition, we demonstrated expression of the gene encoding vaspin in the gastric mucosa in humans, and found that this was subject to regional variations.
Conclusions/interpretation: Our data suggest a previously unrecognised role of vaspin in the regulation of food intake. We postulate that vaspin inhibits a protease that degrades an anti-orexigenic factor.