Intranasal ketamine mitigates radiation-induced brain injury in a rabbit model by modulating ECM/PNN markers and neuroinflammation, with in vivo 1H-MR spectroscopy readouts.

INTRODUCTION

Radiation-induced brain injury causes significant neurotoxicity and cognitive dysfunction in patients undergoing radiotherapy for brain tumors. This study aimed to evaluate the neuroprotective effects of intranasal ketamine on radiation-induced brain injury, specifically focusing on its modulation of perineuronal networks (PNNs), extracellular matrix components, and neuroinflammation.

MATERIALS AND

METHODS

Eighteen male New Zealand White Rabbits were divided into three groups: normal controls, irradiation (IR) with saline (IR + saline), and IR with ketamine (IR + ketamine). Whole-brain IR (20 Gy) was applied to the IR groups, and ketamine (2 mg/kg/day) was administered intranasally for 15 days. Biochemical markers, including malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), brain-derived neurotrophic factor (BDNF), ADAMTS4, and syndecan-1 levels, were measured. Histopathological analysis of hippocampal and cerebellar regions assessed neuronal survival and astrogliosis. Magnetic resonance spectroscopy (MRS) evaluated lactate and N-acetylaspartate (NAA) levels, reflecting metabolic and neuronal integrity.

RESULTS

Ketamine administration significantly reduced oxidative stress (MDA) and inflammatory markers (TNF-α) while restoring BDNF levels compared to the IR + saline group. ADAMTS4 and syndecan-1 levels were reduced, changes consistent with PNN-associated extracellular matrix dynamics, but without direct confirmation by core PNN markers such as aggrecan or WFA staining. Histopathology showed increased neuronal survival and decreased reactive astrogliosis in ketamine-treated groups. 1H-MRS provided supporting evidence for metabolic changes (↓lactate, ↑NAA) consistent with improved mitochondrial function and neuronal integrity.

CONCLUSION

Intranasal ketamine demonstrates significant neuroprotective effects in a radiation-induced brain injury model by reducing oxidative stress and inflammation, modulating extracellular matrix components, and preserving neuronal integrity. These findings highlight ketamine's potential as a therapeutic agent, although direct PNN markers and broader cytokine panels were not assessed. Overall, ketamine showed neuroprotective effects across biochemical, histological, and MRS-supported metabolic readouts.