Cisplatin Induces BDNF Downregulation in Middle-Aged Female Rat Model while BDNF Enhancement Attenuates Cisplatin Neurotoxicity

Cancer-related cognitive impairments (CRCI) are debilitating consequences of cancer treatment with platinum agents (e.g., cisplatin) that greatly alter cancer survivors health-related quality of life. Brain-derived neurotrophic factor (BDNF) plays an essential role in neurogenesis, learning, and memory, and the reduction of BDNF is associated with the development of cognitive impairment in various neurological disorders, including CRCI. Our previous CRCI rodent studies have shown that cisplatin reduces hippocampal neurogenesis and BDNF expression and increases hippocampal apoptosis, which is associated with cognitive impairments. Few studies have reported on the effects of chemotherapy and medical stress on serum BDNF levels and cognition in middle-aged female rat models. The present study aimed to compare the effects of medical stress and cisplatin on serum BDNF levels and cognitive performance in 9-month-old female Sprague Dawley rats to age-matched controls. Serum BDNF levels were collected longitudinally during cisplatin treatment, and cognitive function was assessed by novel object recognition (NOR) 14 weeks post-cisplatin initiation. Terminal BDNF levels were collected ten weeks after cisplatin completion. We also screened three BDNF-augmenting compounds, riluzole, ampakine CX546, and CX1739, for their neuroprotective effects on hippocampal neurons, in vitro. We assessed dendritic arborization by Sholl analysis and dendritic spine density by quantifying postsynaptic density-95 (PSD95) puncta. Cisplatin and exposure to medical stress reduced serum BDNF levels and impaired object discrimination in NOR compared to age-matched controls. Pharmacological BDNF augmentation protected neurons against cisplatin-induced reductions in dendritic branching and PSD95. Ampakines (CX546 and CX1739) but not riluzole altered the antitumor efficacy of cisplatin in two human ovarian cancer cell lines, OVCAR8 and SKOV3.ip1, in vitro. In conclusion, we established the first middle-aged rat model of cisplatin-induced CRCI, assessing the contribution of medical stress and longitudinal changes in BDNF levels with cognitive function. We conducted an in vitro screening of BDNF-enhancing agents to evaluate their potential neuroprotective effects against cisplatin-induced neurotoxicity and their effect on ovarian cancer cell viability.