Activity-dependent neural tissue oxidation emits intrinsic ultraweak photons

Living organisms have been known to spontaneously emit ultraweak photons in vivo and in vitro. Origin of the photon emission remains unclear, especial ly in the nervous system. The spontaneous ultraweak photon emission was det ected here from cultured rat cerebellar granule neurons using a photomultip lier tube which was highly sensitive to visible light. The photon emission was facilitated by the membrane depolarization of neurons by a high concent ration of K+ and was attenuated by application of tetrodotoxin or removal o f extracellular Ca2+, indicating the photon emission depending on the neuro nal activity and likely on the cellular metabolism. Furthermore, almost all the photon emission was arrested by 2,4-dinitrophenylhydrazine, indicating that the photon emission would be derived from oxidized molecules. Detecti on of the spontaneous ultraweak photon emission will realize noninvasive an d real-time monitoring of the redox state of neural tissue corresponding to the neuronal activity and metabolism. (C) 2001 Academic Press.