Serum leptin and ghrelin levels in response to methylprednisolone injection in healthy dogs

The aim of this study was to investigate the effects of methylprednisolone treatment on serum leptin and ghrelin levels in healthy dogs (n = 40). After 14 h of fasting, the dogs were injected intramuscularly with saline (control group) or methylprednisolone (1, 5 or 10 mg/kg). Blood samples were collected prior to (baseline) and 2, 3, 4, 8, 12 and 24 h subsequent to the treatments. Serum leptin and ghrelin were measured by radioimmunoassay.The mean baseline serum leptin and ghrelin were 2.5 ± 0.1 ng/mL (n = 40) and 35.0 ± 2.1 pg/mL (n = 40), respectively. In the control dogs, serum leptin, but not ghrelin levels showed a significant fluctuation during the 24 h observation period. Serum leptin increased significantly (p < 0.05–0.01) between 2 and 12 h after 1 mg/kg of methylprednisolone. Serum leptin levels showed biphasic response to 5 mg/kg of methylprednisolone: its level decreased to 1.9 ± 0.1 ng/mL (p < 0.01) at 2 h and increased at 12 h (2.6 ± 0.1 ng/mL) (p < 0.01). In response to 10 mg/kg of methylprednisolone, serum leptin levels decreased significantly (p < 0.01) for 24 h. Serum ghrelin levels decreased to 19 ± 5 pg/mL at 2–3 h (p < 0.01) or increased to 87 ± 18 pg/mL at 3–8 h (p < 0.05–0.01) after 1 mg/kg of methylprednisolone or 10 mg/kg of methylprednisolone, respectively. Serum ghrelin levels did not change at any time point during 24 h observation period after 5 mg/kg of methylprednisolone. There was a significant (p < 0.001) inverse correlation (r = −0.635) between serum leptin and ghrelin levels.In conclusion, we found that methylprednisolone increases or decreases serum leptin and ghrelin levels depending upon its dose and there is a negative correlation between serum leptin and ghrelin levels after methylprednisolone administration.