Alpha-synuclein expression in oxytocin neurons of young and old bovine brains

• Published in: Journal of Reproduction and Development Vol. 70; no. 4; pp. 213 - 222
• Main Authors: NIYONZIMA, Yvan Bienvenu, ASATO, Yuuki, KADOKAWA, Hiroya
• Format: Journal Article
• Language: English
• Published: Japan The Society for Reproduction and Development 01.01.2024; Japan Science and Technology Agency
• Subjects: Aging; Aging - metabolism; alpha-Synuclein - metabolism; Animals; Brain - metabolism; Cattle; Central nervous system; Confocal microscopy; Cortex; Female; Gene expression; Hippocampus; Hippocampus - metabolism; Hormones; Hypothalamus; Immunohistochemistry; Infertility; Light microscopy; Microscopy; mRNA; Neurons; Neurons - metabolism; Oxytocin; Oxytocin - metabolism; Paraventricular hypothalamic nucleus; Paraventricular Hypothalamic Nucleus - metabolism; Pituitary (posterior); Pituitary Gland, Posterior - metabolism; Polarized light; Posterior pituitary gland; RNA, Messenger - metabolism; Suprachiasmatic nucleus; Suprachiasmatic Nucleus - metabolism; Supraoptic nucleus; Supraoptic Nucleus - metabolism; Synuclein; Western blotting; Suprachiasmatic nucleus; Aging; Posterior pituitary gland; Paraventricular hypothalamic nucleus; Supraoptic nucleus
• ISSN: 0916-8818; 1348-4400
• DOI: 10.1262/jrd.2024-020

Understanding of central nervous system mechanisms underlying age-related infertility remains limited. Fibril α-synuclein, distinct from its monomeric form, is implicated in age-related diseases. Notably, fibril α-synuclein spreads among neurons, similar to prions, from damaged old neurons in cortex and hippocampus to healthy neurons. However, less is known whether α-synuclein propagates into oxytocin neurons, which play crucial roles in reproduction. We compared α-synuclein expression in the oxytocin neurons in suprachiasmatic nucleus (SCN), supraoptic nucleus (SON), paraventricular hypothalamic nucleus (PVN), and posterior pituitary (PP) gland of healthy heifers and aged cows to determine its role in age-related infertility. We analyzed mRNA and protein expression, along with Congo red histochemistry and fluorescent immunohistochemistry for oxytocin and α-synuclein, followed by confocal microscopy with Congo red staining. Both mRNA and protein expressions of α-synuclein were confirmed in the bovine cortex, hippocampus, SCN, SON, PVN, and PP tissues. Significant differences in α-synuclein mRNA expressions were observed in the cortex and hippocampus between young heifers and old cows. Western blots showed five bands of α-synuclein, probably reflecting monomers, dimers, and oligomers, in the cortex, hippocampus, SCN, SON, PVN, and PP tissues, and there were significant differences in some bands between the young heifers and old cows. Bright-field and polarized light microscopy did not detect obvious amyloid deposition in the aged hypothalami; however, higher-sensitive confocal microscopy unveiled strong positive signals for Congo red and α-synuclein in oxytocin neurons in the aged hypothalami. α-synuclein was expressed in oxytocin neurons, and some differences were observed between young and old hypothalami.