Thermal cycling stimulation via nasal inhalation attenuates Aβ25-35-induced cognitive deficits in C57BL/6 mice

Alzheimers disease (AD) continues to pose a significant public health challenge, with current treatments demonstrating limited effectiveness, partly due to the difficulty of delivering therapeutics across the blood-brain barrier (BBB). The nose-to-brain (N-2-B) pathway offers a promising alternative, enabling pharmacological agents to circumvent the BBB. However, to date, no drugs have been successfully implemented in clinical settings for the treatment of AD via this route, underscoring the necessity for additional research in this area. Mild stress is thought to activate intrinsic protective mechanisms against neurodegeneration, but traditional methods of inducing stress often lack both specificity and practicality. To address this limitation, we propose the inhalation of mildly heated air as a form of thermal stimulation, which utilizes the N-2-B pathway to induce mild stress and stimulate cerebral activity. This study employs the method of thermal cycling-hyperthermia (TC-HT) technique [Chao C.Y. et al., U.S. patent 11753634, 2023 & Chao C.Y. et al., U.S. patent Appl. No. 18/864192, 2024] into a new treatment, adapted as thermal cycling-stimulation via nasal inhalation (TCSNI), which provides cyclic stimulation to maintain pathway activity while minimizing thermal injury. In this study, we assessed the health and olfactory effects of TCSNI in C57BL/6 mice and found no adverse effects. In experimental groups administered with {beta}-amyloid (A{beta}), TCSNI treatment resulted in significant enhancements in cognitive performance as evidenced by Y-maze and novel object recognition (NOR) assessments, suggesting an improvement in cognitive function. Protein analyses conducted on the hippocampus of the mice indicated a reduction in A{beta} accumulation, alongside increased expression of heat shock protein 70 (HSP70) and insulin-degrading enzyme (IDE) expression, as well as elevated levels of phosphorylated Akt (p-Akt). These results suggest that N-2-B-delivered TCSNI effectively modulates protein expression and enhances cognitive function, highlighting its potential for further exploration in AD treatment.