Aims: 

Adipokines, and ghrelin are beside the regulation of metabolism and food intake involved in inflammatory processes. This study investigates whether the development of inflammation is associated with changes in adiponectin, leptin, and ghrelin in rats, and whether changes in peripheral leptin and ghrelin levels affect the expressions of their respective receptors in the hypothalamic arcuate nuclei.

Methods: 

Adjuvant arthritis (AA) was induced to male Lewis rats using complete Freund's adjuvant. Food consumption and body weight were monitored for 18 days of the disease. Hormones were determined by radioimmunoassay. mRNA expression for ghrelin receptor-Ghsr and leptin receptor-OB-Rb was determined by quantitative TaqMan PCR.

Results: 

Arthritic rats had decreased food intake and body weight during the whole course of the study. Plasma adiponectin was lowered on days 4, 12, and 18 of AA, ghrelin was reduced on days 12, and 18, and plasma leptin and leptin content in fat were decreased on days 12, 15, and 18. Expression of Ghsr was upregulated on days 4, 9, and 18 of AA, and expression of OB-Rb was downregulated on day 4 and upregulated on day 18.

Conclusion: 

The decrease of body weight and fat loss led to lowered levels of adipokines, and their full immunomodulatory effects could not be manifested. Low leptin levels were expected to increase food intake by desinhibition of orexigenic pathway in hypothalamus. However, the inflammatory insult caused loss of appetite, resulting in low ghrelin levels and consequently in lack of food intake stimulation.

Supported: VZ 002162018, and GACR 305/06/0427.