Effects of leptin on the rat cervix

The cervix is one of the most dynamic tissues in the body. During pregnancy and parturition the cervix undergoes dramatic changes. The rat cervix changes from a rigid cartilaginous tissue to a tissue that is remarkably malleable and viscous. Most of the growth of the cervix takes place during the last half of pregnancy. This growth is characterized by both an increase in wet and dry weight. However, the mechanisms causing these physiological changes are not completely understood.; The regulation of the physiological changes that take place in the cervix is generally thought to be the result of hormonal influences and mechanical stress created by the fetus. Relaxin increases the overall growth of the cervix by promoting vascularization, eosinophilic invasion, and cellular proliferation. However, these changes are dependent upon the presence of estrogen. Estrogen alone is not sufficient to bring about these changes and estrogen without relaxin results in a more rigid cervix. Further, the combination of relaxin and estrogen is not sufficient to completely recreate the characteristics of the cervix of an intact pregnant rat.; Within the last decade leptin, a protein hormone, has been discovered. Recent reports have implicated leptin in conception, implantation, cellular proliferation and extracellular matrix modulation. Circulating leptin concentrations have also been shown to increase three fold during pregnancy. These reports provide a basis for the hypothesis that leptin is acting on the cervix of the rat during pregnancy to increase collagen content, modulate collagen fiber organization and increase cellular proliferation. The overall hypothesis tested was that leptin aids in the process of cervical remodeling during pregnancy and parturition.; The investigations conducted indicate that leptin, in the presence of relaxin and estrogen, increases cervical extensibility, wet weight and dry weight. Leptin also is capable of increasing cellular proliferation and collagen accumulation in the cervix. However, the studies conducted indicate that leptin may not modulate the extra-cellular matrix through matrix metalloproteinases, but leptin appears to play a role in the disorganization of collagen fibers.