Expression of connexin-26, -32, and -43 gap junction proteins in the porcine cervix and uterus during pregnancy and relaxin-induced growth.

Connexin (CX) proteins participate in growth, differentiation, and tissue remodeling. Relaxin-stimulated reproductive tissue growth and remodeling may be facilitated by enhanced intracellular communication. This study was an examination of the effects of relaxin in vivo on expression of CX-26, CX-32, and CX-43 in the cervix and uterus of prepubertal pigs. In addition, expression of these proteins was monitored in the sow uterus during pregnancy. Relaxin was administered to prepubertal gilts every 6 h for 54 h. CX expression was characterized by immunoblotting and localized by immunofluorescence. Significant increases in all three CXs were observed in the cervix following relaxin treatment (P < 0.05). Uterine CX proteins were also significantly higher (P < 0.05) in relaxin-treated animals compared to controls. The CX protein level in relaxin-treated animals was similar to that observed during the second half of pregnancy, but below levels found in mature, nonpregnant sows. This is the first evidence for specific CX expression in the porcine cervix, and the first study to show that relaxin increases the expression of CX proteins in the porcine uterus and cervix. The data show that CX proteins are differentially regulated in the uterus of the pig during pregnancy. These data support a role for CX-mediated communication during relaxin-induced reproductive tissue growth and remodeling.