Molecular and functional characterization of TRPV4 channels in pregnant and nonpregnant mouse uterus.

Aims: The aim of the present study was to characterize TRPV4 channels in pregnant and nonpregnant mouse uterus and examine their functional role in spontaneous and agonist-induced contractions.

Main Methods: We used RT-PCR, Western blot and immunohistochemistry experiments to demonstrate the presence of TRPV4 mRNA and protein, respectively in both pregnant and nonpregnant mouse uterus. Tension experiments were conducted for functional characterization of the TRPV4 channels.

Key Findings: TRPV4 mRNA and protein were detected in both pregnant and nonpregnant mouse uterus with distribution in both endometrium and myometrium. The TRPV4 channel agonist GSK1016790A (GSK) increased myometrial contraction in pregnant (Emax 336.8±21.35%; pD2 7.79±0.29) and nonpregnant (Emax 238±28.13%; pD2 7.61±0.57) animals. HC067047 (1μM), a selective blocker of the TRPV4 channel, antagonized the contractions to GSK in pregnant (Emax 171±18.26%; pD2 6.58±0.37) and nonpregnant (Emax 78.12±9.32%; pD2 7.54±0.9) uteri. Further, HC067047 (1μM) inhibited contractions induced by PGF2α in the pregnant (Emax 183.2±13.94%; pD2 7.01±0.30 versus control Emax 495.7±42.49%; pD2 7.12±0.24) and nonpregnant (Emax 105.3±7.10%; pD2 7.24±0.34 versus control Emax 232.5±12.27%; pD2 7.83±0.29) uteri.

Significance: TRPV4 channels are present in the pregnant and nonpregnant mouse uteri, and their activation by endogenous ligands like prostaglandin increases myometrial contractility. Thus, the TRPV4 channel can be an important target in reducing myometrial contractility in preterm labor.