Leptin, adiponectin and serotonin levels in lean and obese dogs

Abstract

Background: Serotonin (5-hydroytryptamine or 5HT) is associated with numerous behavioral and psychological factors and is a biochemical marker of mood. 5HT is involved in the hypothalamic regulation of energy consumption. 5HT controls appetite in the central nerve system (CNS) and stimulates intestinal mobility. There are few studies looking at the role of 5HT and the relationship between peripheral circulating serotonin and obesity. The aim of this study was to find any differences in leptin, adiponectin, and 5HT between lean and obese dogs and to identify correlations among these factors.

Results: Leptin, triglyceride (TG) and cholesterol levels were higher in the obese group (all p < 0.01). Adiponectin and 5HT levels were higher in the lean group compared to the obese group (p < 0.01). Leptin (r = 0.628, p < 0.01), TG (r = 0.491, p < 0.01) and cholesterol (r = 0.419, p < 0.01) were positively correlated with body condition score (BCS), and adiponectin (r = -0.446, p < 0.01) and 5HT (r = -0.490, p < 0.01) were negatively correlated with BCS. Leptin was negatively correlated with adiponectin (r = -0.294, p < 0.01) and 5HT (r = -0.343, p < 0.01). 5HT was negatively correlated with leptin (r = -0.343, p < 0.01), TG (r = -0.268, p < 0.05) and cholesterol (r = -0.357, p < 0.05).

Conclusions: 5HT is an important appetite control neurotransmitter, but there are limited studies for 5HT levels related to obesity in dogs. To the best of our knowledge, this is the first study to evaluate peripheral 5HT levels in obese dogs. From this research, we can assume that 5HT may be correlated with canine obesity. Further studies will be needed to further elucidate the role of low serum 5HT levels in canine obesity.

Figure 1

Serotonin concentration between lean and obese groups. Data are presented as boxes and whiskers. Each box includes the interquartile range, whereas the line within a box represents the median, and the whiskers represent the range, extending to a maximum of 1.5 times the interquartile range. Serotonin levels were significantly lower in obese group compared with that of lean group. **p < 0.01: significant difference were observed between lean and obese groups.

Figure 2

Correlation between BCS and obesity parameters. (A) BCS and adiponectin showed negative correlation (r = -0.446, p < 0.01). (B) BCS and Cholesterol showed positive correlation (r = 0.419, p < 0.01). (C) BCS and leptin showed positive correlation (r = 0.628, p < 0.01). (D) BCS and serotonin showed negative correlation (r = -0.490, p < 0.01). (E) BCS and tirglyceride showed positive correlation (r = 0.491, p < 0.01).

Figure 3

Correlation among leptin, adiponectin, cholesterol and serotonin. (A) Leptin and adiponectin showed negative correlation (r = -0.294, p < 0.01). (B) Leptin and Cholesterol showed positive correlation (r = 0.516, p < 0.01). (C) Leptin and serotonin showed negative correlation (r = -0.343, p < 0.01).