Characteristics of changes in lipids of granulation fibrous tissue of rats subjected to different doses and modes of melatonin administration

Melatonin influences the time-course of changes of lipids in granulation fibrous tissue in rats. Its effect depends on a dose, modes of administration (intraperitonial, subcutaneous or local) and duration of treatment. Intraperitonial administration of a single dose of melatonin (4 mg/kg) did not influence lipid content in the granulation fibrous tissue, while repeated injections of this hormone limited the increase in contents of lipids and phospholipids on the 5th and 8th days of regeneration. Long-term subcutaneous injections of melatonin caused distinct changes of lipids: at the dose of 0.3 mg/kg it prevented, and at the dose of 4 mg/kg it promoted the increase of lipid content in the granulation fibrous tissue on the fifth day of this study. Local application of melatonin solution (1.5 mg/ml) in early periods of regeneration caused insignificant changes of total lipids and total phospholipids in the granulation fibrous tissue. However, the higher concentration (15 mg/ml) of melatonin caused the decrease of total lipids due to reduced content of cholesterol and triglycerides and the increase of total phospholipids and some of their fractions.