Pinealectomy leads to melatonin deficiency, which is known to disrupt circadian clock regulation and may increase vulnerability of the hippocampus to oxidative stress and neuroinflammatory processes. The objective of this study was to examine the gene expression levels of circadian locomotor output cycles kaput (CLOCK), brain and muscle ARNT-like 1 (BMAL1), period circadian regulator 1 (PER1), cryptochrome circadian regulator 1 (CRY1), brain-derived neurotrophic factor (BDNF), and interleukin-6 (IL-6) in the hippocampus to elucidate the impact of pinealectomy-induced circadian dysregulation on these gene expressions and to assess its association with hippocampal alterations. A total of 30 Wistar rats were randomly divided into three groups: Control, Sham, and Pinealectomy (PNX) (n = 10 per group). Gene expression levels were analyzed using quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical analysis was performed to assess caspase-3 and glial fibrillary acidic protein (GFAP) immunoreactivity. In addition, oxidative stress parameters, including malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), as well as the inflammatory marker tumor necrosis factor-alpha (TNF-α), were measured. The pinealectomy group showed a significant downregulation of BMAL1, BDNF, CLOCK, CRY1, and PER1 gene expression levels, with decreases ranging from approximately 60% to 83% compared with the sham and control groups, whereas IL-6 expression was significantly increased by approximately 185% (p < 0.05). Immunohistochemical analysis demonstrated significantly increased caspase-3 and GFAP immunoreactivity in the PNX group. Furthermore, pinealectomy resulted in a significant increase in MDA and TNF-α levels, accompanied by marked decreases in SOD, CAT, and GSH levels (p < 0.05). In conclusion, pinealectomy is associated with significant disruption of hippocampal circadian clock gene expression, accompanied by oxidative stress, neuroinflammation, and histopathological alterations. These findings highlight the critical role of circadian regulation in maintaining hippocampal cellular integrity.
Can et al. (Tue,) studied this question.