Melatonin Modulates Phosphorylation of 2′,3′-Cyclic Nucleotide-3′-Phosphodiesterase in the Presence of Protoporphyrin IX in the Brain Mitochondria of Rats during the Functioning of the Non-Specific Mitochondrial Pore

Melatonin (N-acetyl-5-methoxytryptamine), a neuroendocrine hormone of the pineal gland, participates in the modulation of the mitochondrial nonspecific pore (mitochondrial permeability transition pore, mPTP). According to the results we obtained, protoporphyrin IX (PPIX, a ligand of the TSPO translocator protein) induces the opening of the mPTP in brain mitochondria; melatonin slows the induction of the mPTP in rat brain mitochondria incubated with PPIX. Induction of the mPTP activates protein kinases/protein phosphatases that are involved in the regulation of protein phosphorylation. The TSPO modulates protein phosphorylation; in the presence of PPIX, the phosphorylation of 2′,3′-cyclic nucleotide-3′-phosphodiesterase (CNPase) increases. Here, we showed an increase in the degree of phosphorylation of CNPase in PPIX-treated rat brain mitochondria, a melatonin-induced decrease in level of CNPase phosphorylation in mitochondria incubated with PPIX; hence, we propose that melatonin participates in TSPOmodulated protein phosphorylation.