This beta-alanine-histamine peptide, known as carcinine is a product of the action of N-beta-alanyl dopamine synthetase on histamine. Histamine is thought to be taken up by glial cells when it gets released following excitation by light induced depolarization of photoreceptor cell in Drosophila. The peptide is further released by the glial cells and taken up by the presynaptic neuron. Once in the photoreceptor cell, carcinine is converted back to histamine by the enzyme N-beta-alanyl-dopamine hydrolase. This is a natural imidazole-containing peptide derivative with antioxidant activity. It has been shown to scavenge 4-hydroxynonenal and offers neuroprotection to mouse retina.
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