Effect of TLQ-21 peripheral injection on food intake and reproduction mechanisms in female Siberian Hamsters

TLQP-21 is one of the VGF peptides belonging to the TLQP family. TLQP localization has been reported in rat and hamster pituitary cells, rat ovary, rat WAT and BAT fibres, and rat and hamster hypothalamus. Its central action on metabolism and reproduction is widely known; however there still less information about its peripheral role in food and reproduction mechanisms. Aim of our study was to determine the effect of the TLQP-21 on food intake, body weight and reproductive mechanisms. Female siberian hamsters in their short day (SD) sate (winter phenotype) underwent, under gaseous anaesthesia, insertion of subcutaneous alzet mini-pump (1mg/Kg per day, 7 days) filled with vehicle (n=7) or TLQP-21 (n=8). After injection, multiple respiratory and feeding behaviour parameters included oxygen consumption and CO2 production were measured using a Comprehensive Lab Animal Monitoring System (CLAMS) where the animals were singly housed for 7 days. After a week, animals were sacrificed, for tissues sampling. The blood was collected from each heart, for FSH and leptin measurements through ELISA, as well as ovaries for histological analysis. Results showed that continuous infusion of TLQP-21 significantly reduced body weight, (p=0.04) and cumulative food intake (p=0.03). Oxygen consumption (p=0.03), carbon dioxide production (p=0.04) and energy expenditure (p=0.04) were instead significantly increased. Furthermore, meal duration and food intake were both reduced during the dark phase while meal frequency was increased. TLQP-21 injection did not affect the blood levels of FSH or leptin, nor the ovaries that remained in the typical SD state, with no mature follicles. In conclusion, TLQ-21 peripheral injection affects food intake and energy metabolism but not reproductive mechanisms.