Metallothionein-I-II expression in young and adult bovine pineal gland

Aging is characterized, among other features, by an increased concentration of metal ions in the brain that may contribute to a greater increase in free radicals production. The present paper reports data regarding the concentration of some relevant metal ions (Cu, Fe, Mn, Zn), as well as the immunopositivity of metallothionein-I-II and GFAP in the bovine pineal gland with respect to animal aging. The pineal gland of young bovines displays several immunoreactive metallothionein-I-II positive elements in the parenchyma, whose number decreases with age. We also report that a well defined group of neurons bordering the third ventricle and located close to the subcommissural organ shows an intense metallothionein-I-II immunopositivity. The presence of metallothionein-I-II was confirmed by means of liquid chromatography coupled to tandem mass spectrometry. In particular, it proved possible to identify the amino acid sequences of the unique tryptic peptide not containing cysteine and two pepsin fragments containing cysteines. In conclusion, our data suggest the presence of a metallothionein-I-II expressing system in the pineal gland and ventricle-adjacent areas of the bovine epithalamus might possibly be related to the anti-aging effects of melatonin.