Ex-vivo effect of leptin and gaba on spontaneous uterine contractility in pregnant and non-pregnant rats

Abstract

Obesity has also been reported to cause bad obstetric outcomesand is associated with disturbances in leptin and gamma-aminobutyric acid (GABA) levels.Difficulty in parturition or even emergency operative delivery can occur from disturbances in uterine contractility. There are conflicting reports on the effect of leptin on uterine contractility and very few studies on the GABA and uterine contractility.This study was therefore aimed at investigating the responsiveness of the pregnant and non-pregnant rat uterus to cumulative doses of recombinant leptin and GABA. Pregnant rats at gestational day (GD) 20 and non-pregnant rats in the oestrus phase were utilized.The uterus was isolatedand the force and frequency of uterine contractions for GABA (10-4-7mg/ml) and leptin (10-2- 1μg/ml) were measured cumulatively.Non-pregnant and pregnant rats showed no statistically significant difference (P>0.05) in amplitude of contractions in the presence of leptin, however the frequency of contractions (P<0.05) were significantly reduced in both non-pregnant and pregnant uteri. There was also no significant change (P>0.05) in the amplitude of uterine contractions in the presence of GABA but again the frequency ofcontractions were significantly reduced (P<0.05) in the non-pregnant uterus. This study has shown that leptin had an inhibitory effect on the uterine contraction frequency in both pregnant and non-pregnant states while GABA inhibited uterine contraction frequency only in the non-pregnant uterus. It can therefore be inferred that the bad obstetric outcomes associated with obesity especially with regards to disorders in uterine contractility during parturition can ascribable to the characteristic hyperleptinaemic state which causes disturbances on GABA levels.

Keywords: GABA, Leptin, Uterine contractility, Infertility, Obesity