Segmental, coronal and subcellular distribution of 2-[125I]iodomelatonin binding sites in the chicken spinal cord.

Radioreceptor and autoradiography studies using chicken spinal cords demonstrated that the binding density of 2-[125I]iodomelatonin ([125I]MEL) was significantly higher in the lumbar segment and the specific binding of [125I]MEL was localized in the gray matter. Subcellularly, different densities of binding sites were localized in the following order: nuclear > microsomal > mitochondrial > cytosolic. Localization of [125I]MEL binding sites in the dorsal gray matter of the chicken spinal cord suggests that melatonin plays a role in regulating the spinal cord functions which may associate with the modulation of temperature and pain transmission and/or visceral and autonomic functions.