Interactions between carnosine and zinc and copper: Implications for neuromodulation and neuroprotection

This review examines Interactions in the mammalian central nervous system ( CNS) between carnosine and the endogenous transition metals zinc and copper . Although the relationship between these substances may be applicable to o ther brain regions, the focus is on the olfactory system where these substa nces may have special significance. Carnosine is not only highly concentrat ed in the olfactory system, but it is also contained in neurons (in contras t to glia cells in most of the brain) and has many features of a neurotrans mitter, Whereas the function of carnosine in the CNS is not well understood , we review evidence that suggests that it may act as both a neuromodulator and a neuroprotective agent. Although zinc and/or copper are found in many neuronal pathways in the brain, the concentrations of zinc and copper in t he olfactory bulb (the target of afferent input from sensory neurons in the nose) are among the highest in the CNS, Included in the multitude of physi ological roles that zinc and copper play in the CNS is modulation of neuron al excitability, However, zinc and copper also have been implicated in a va riety of neurologic conditions including Alzheimer's disease, Parkinson's d isease, stroke, and seizures. Here we review the modulatory effects that ca rnosine can have on zinc and copper's abilities to. influence neuronal exci tability and to exert neurotoxic effects in the olfactory system. Other asp ects of carnosine in the CNS are reviewed elsewhere in this issue.