Quantitative analysis of collagen fibrillar structure in canine uterus exposed to acetate of medroxyprogesterone using second harmonic generation microscopy

Collagen is the most abundant structural protein found in organs and is responsible for providing tissues with structure and function. In order to investigate in canine uteri the potential effect of medroxyprogesterone acetate (MPA) on the changes in collagen deposition were grouped as nulliparous (n=11), multiparous (n=11) and treated with MPA (n=11; nulliparous with two treatments; 5 mg/kg; i.m.). The amount of collagen was studied in the fold and basal regions of the endometrium and myometrium using second harmonic generation with a two-photon spectral confocal microscope, quantified using ImageJ software with a color segmentation plugin, was expressed as fraction area (%) and analyzed by ANOVA (p<0,05). No differences were observed between groups in the fold (p=0,3995) or base (p=0,7392) of the endometrium and myometrium (p=0,1781). In conclusion, our data demonstrate that two doses of MPA (5 mg/kg; i.m.) do not affect the total collagen deposition in canine uteri undergoing contraceptive treatment.