IMMUNOCYTOCHEMICAL AND BIOCHEMICAL-EVIDENCE FOR AROMATASE IN NEURONS OF THE RETINA, OPTIC TECTUM AND RETINOTECTAL PATHWAYS IN GOLDFISH

Using an animal model in which neural aromatase is apparently overexpr essed (the goldfish, Carassius auratus) and an anti-human placental an tibody which specifically crossreacts with goldfish brain aromatase, a romatase-immunoreactive neuronal cell bodies and fibers have been loca lized within the retina. These include a subset of horizontal cells, b ipolar cells, and amacrine cells of the inner nuclear layer, some fibe rs of the outer and inner synaptic layers and certain cells of the gan glion cell layer; photoreceptors were never labeled. Some ganglion cel l projections to the brain via the optic nerve and optic tract were ar omatase-positive, as were small neurons of the stratum periventricular e (SPV) and fibers of two other strata of the optic tectum. Aromatase activity, as measured by [H-3]estrogen formation from [H-3]androgen by tissue homogenates and cell cultures, confirmed the presence of aroma tase in retina and in brain regions containing the optic tectum. This localization of the rate-limiting enzyme in estrogen biosynthesis sugg ests that neuroestrogen derived from circulating androgen may modulate transmission and integration of visual information important for repr oduction in this species.