Associations of serum kisspeptin levels with metabolic and reproductive parameters in men

Central kisspeptin action is well known in reproductive regulation; however, its peripheral action is not well understood. This study aimed to 1) compare serum or cerebrospinal fluid (CSF) kisspeptin levels between different body mass index (BMI) groups 2) compare the levels of kisspeptin between serum and CSF, and 3) determine correlations between serum or CSF kisspeptin levels with clinical, metabolic, and reproductive parameters. There were 40 male subjects undergoing operations with lumbar puncture anesthesia. Subgroup analysis was performed to compare between the normal (n = 12), overweight (n = 10), and obese groups (n = 17). One lean subject was recruited for correlation analysis. Serum kisspeptin levels were significantly higher in the obese group when compared to the normal weight and overweight groups even after adjusting for age or diastolic blood pressure (DBP) (p < 0.05 all). Serum leptin levels were significantly higher in the obese group when compared to the normal weight and overweight groups (p < 0.05 all). CSF kisspeptin levels were below the minimum detectable concentration for the assay (<0.06 ng/mL). Serum kisspeptin was positively correlated with body weight, BMI, plasma insulin, the homeostatic model assessment for insulin resistance (HOMA-IR), and serum leptin but was negatively correlated with plasma LH (p < 0.05 all). In conclusion, serum kisspeptin was related to obesity, leptin, insulin, and insulin resistance, while CSF kisspeptin was below the limits of detection. Thus, peripheral kisspeptin might have a role in metabolic regulation.