Detection of dopa-positive cells in mouse ovaries in response to ocular exposure to ultraviolet B rays.

It is known that the levels of hormones secreted from the pituitary gland are increased by ultraviolet B (UVB) eye irradiation. The ovaries are affected by the hormones secreted from the pituitary gland. Therefore, we observed the influence of UVB eye irradiation on the ovaries. In this study, a 2.5 kJ/m(2) dose of UVB irradiation was delivered by a sunlamp to the eye or the ear of C57BL/6j female mice. Five days after UVB irradiation, we removed the ovaries. The plasma levels of α-melanocyte-stimulating hormone (α-MSH), adrenocorticotropic hormone (ACTH), and β-endorphin were increased 24 h after UVB irradiation of either the eye or the ear. The amounts of ACTH and α-MSH were decreased 5 days after UVB irradiation. However, the β-endorphin level 5 days after UVB eye irradiation did not decrease. In addition, UVB eye irradiation increased the expression of dopa-positive cells, tyrosinase, and dopa decarboxylase, and also increased the immunoreactivity of melanocortin-1 receptor in the ovaries. The dopamine content in the plasma was also increased. These results suggest that the melanin and dopamine systems of the ovary are affected by UVB eye irradiation, and the synthesized dopamine is maintained at high levels as β-endorphin.