Expression and Localization of Epidermal Growth Factor in the Testosterone administered Submandibular Gland of the Rat

Kim, Jin Gook; Jung, Ki Young; Park, Kyung Ho; Ko, Jeong Sik; Ahn, E Tay

Abstract

The submandibular gland of rodents is under-developed state at birth, and the differentiation takes place post-natally under the control of neuronal and hormonal factors. In particular, testosterone plays an important role in the differentiation of duct system of rodent submandibular gland, but the underlying mechanism is not clear. To clarify the relationship between testosterone administration and differentiation of granular convoluted tubular (GCT) cells in immature rats, the expression and localization of epidermal growth factor (EGF), as a marker of GCT cell, on the submandibular gland of 3 week -old rats were examined by means of RT -PCR, immunohistochemistry and in situ hybridization. 1) RT-PCR demonstrated gradual increases of the amounts of EGF mRNA following the administration of testosterone for 1~4 days. 2) Immunohistochemistry shows that the occurrence of EGF protein first appeared at the striated duct after the administration of testosterone for 1 day, and had increased in number at the duct portions, 2 and 4 days after the testosterone administration. 3) In situ hybridization also indicates testosterone-induced expression of EGF mRNA became evident as EGF protein at the duct system of rat submandibular gland. These results suggest that testosterone is involved in the differentiation of the granular convoluted tubular cells, during the post-natal development of the rat submandibular gland.