Background: It has been suggested that hormonal changes may influence alpha-amylase activity during sex cycle. The aim of this study was to evaluate these changes in serum and different tissues during sex cycle in female rats.
Material/Methods: The animals were assigned to proestrus, estrus, and diestrus groups depending on vaginal smears. We measured the activities of alpha-amylase in the serum, liver, salivary glands, pancreas and ovary of female rats, serum level of calcium, rat luteinising hormone (rLH) and rat follicle stimulating hormone (rFSH). The serum and tissue amylases were also characterized by wide-range polyacrylamide gel isoelectrofocusing.
Results: Statistically significant changes of alpha-amylase activity were found only in the ovary. The activity of alpha-amylase raised from proestrus (mean 303&plusm;124 IU/g) through estrus (mean 157&plusm;123 IU/g) and declined in diestrus (mean 81.9&plusm;51.6 IU/g). There were no statistically significant changes in the serum, liver, salivary glands and pancreas. We found two isoenzymes of alpha-amylase: one peak of amylase, present in the serum, liver, salivary gland and ovary with the mean isoelectric point of ca 5.34 and another present in ovary and pancreas with mean isoelectric point of ca 8.32. The only tissue found to contain both isoamylases was the ovary. We did not find any correlation between serum calcium level and alpha-amylase activity in the serum and ovary.
Conclusions: The pattern of changes of alpha-amylase activity does not depend on the type of isoamylase in the tissue, but probably on the tissue influenced by the sex cycle. The changes of alpha-amylase activity are not mediated by calcium, they seem to result primarily from the profile of sex hormones affecting directly the target tissues.

Keywords: alpha-Amylase, sex cycle, female rats, polyacrylamide gel isoelectrofocusing