The present study investigated the correlation between thyroid hormones (i.e. thyroxine (T4) & triiodothyronine(T3)) and total collagen content in tissues of Duttaphrynus melanostictus. Administration of both T4 and T3 (0.5 μg/gm) separately for seven consecutive days led to changes in the total collagen content of dorsal skin, ventral skin and muscle of both young and adult common Indian toads. Thyroxine is important for both collagen synthesis and matrix metabolism (Yen, 2001). Duttaphrynus melanostictus were collected from Berhampur University campus and acclimated at laboratory conditions for 2/3 days. Levels of collagen were estimated following the method of Neuman and Logan (1950), as modified by Leach (1960). T4 treatment appeared to stimulate the deposition of collagen as evident from values of total collagen of dorsal and ventral skin. On the other hand, T4 treatment inhibits the increase in total collagen in the muscle region. On the contrary, T3 treatment decelerated the collagen deposition in dorsal skin and muscle tissue. A tissue-specific action of T3 administration in common Indian toad was shown in ventral skin where the total collagen content increased though differing to some extent in a degree of response. There is an age-related response to collagen metabolism which is tissue specific. The total collagen content declined during
maturity whereas showing an acceleration in the post-maturity period.

Keywords: T4; T3; Collagen; Duttaphrynus melanostictus.