Endocrine Abstracts

Ghrelin, a recently isolated hormone, has been reported to have modulatory effects on smooth muscle contractility. In this study, we investigated the effects of ghrelin on spontaneous contractions in the rat uterus in vitro.

Myometrium strips were removed from Wistar rats following decapitation and placed in a jacked tissue bath containing Krebs solution at 37 oC and pH 7.4, constantly bubbled with 95% oxygen and 5% carbon dioxide. The myometrial strips were allowed to equilibrate under 0.5 g tension for 30 min and isometric contractions were measured by force displacement transducer. After initiation of spontaneous contractions control contractions were recorded for 10 min and various concentrations of ghrelin were added to the tissue bath cumulatively. The amplitude and frequencies (number of contractions for 10-minute) of contractions were evaluated at 10 min interval before and after applications of ghrelin. Wilcoxon sign ranks test was used for statistical analysis.

Application of ghrelin augmented the spontaneous contractions in myometrial strips. The mean peak amplitudes of contractions were 2.69±0.32 (mean±SEM, n=6), 2.71±0.31 (n=6), 2.92±0.36 (n=6) and 3.46±0.24 g (n=6) under control conditions and after application of 0.01 uM, 0.1 uM and 1 uM ghrelin, respectively. The mean frequency of contractions were 5.17±0.75 (n=6), 5.17±0.75 (n=6), 5.33±0.48 (n=6) and 8.0±0.77 (n=6) under control conditions and after application of 0.01 uM, 0.1 uM and 1 uM ghrelin, respectively. The increase in amplitude and frequency of contractions was significant only after application of 1 uM ghrelin (p<0.05).

Data from this study demonstrated that ghrelin induces spontaneous contractions in a dose dependent manner in the rat myometrium.