Trophinin is expressed in the porcine endometrium during the estrous cycle

We investigated endometrial expression of trophinin mRNA and protein, homophilic cell adhesion molecules, during the estrous cycle of gilts. An immunopositive reaction for trophinin was observed in the luminal and glandular epithelia of the endometrium at all stages of the estrous cycle, but not in endometrial stromal cells or the myometrium. A partial coding sequence of porcine trophinin was similar to sequences in humans and mice, with homologies of 75% and 70%, respectively. As in humans and mice, the trophinin gene is expressed in the endometrium. Trophinin, however, is expressed in the endometrium of the pig throughout the estrous cycle, higher expression levels were observed at some points of the luteal phase, as in humans. These findings suggest that regulation of trophinin gene expression in the pig is different from that in mice, but similar to that in humans. Furthermore, the present results suggest that the pig might be a suitable model for studying the physiological importance of trophinin in early pregnancy in humans.