Assessment of relationship between secretion of melatonin, activity of thyroid, adrenal cortex as well as testes and chosen markers of collagen metabolism in starved rats.

In starved rats the mutual interrelations were studied between the secretion of melatonin (MEL), thyroid hormones (TT[_4], FT[_4], TT[_3], FT[_3], rT[_3]), corticosterone (B), testosterone (T) and some markers of collagen metabolism: serum concentrations of carboxyterminal propeptide of type I procollagen (PICP) and aminoterminal propeptide of type III procollagen (PIIINP) (determined by RIA method) as well as urine concentration of hydroxyproline (OH-Pr) (determined by colorimetric method). Starved rats were found to have significantly increased serum MEL, B, and rT[_3] concentrations while serum values of TT[_4], FT[_4], TT[_3], FT[_3], T and PICP as well as urinary OH-Pr were significantly decreased. The concentrations of PICP, PIIINP and OH-Pr correlated negatively with MEL and B values, but positively with TT[_4] and FT[_4]. It was concluded that starving may change the collagen metabolism in rats indirectly via a modulating effect of changes in MEL, thyroxine and corticosterone.