Pontine changes in metabolites and axonal fibres of rats following four-week alcohol exposure: In vivo diffusion tensor imaging and 1H-magnetic resonance spectroscopy study at 7.0 T

Abstract

Aims: We characterized the metabolite content and axonal fibre changes in the rat pontine, in vivo, using 1H-magnetic resonance spectroscopy (1H-MRS) and diffusion tensor imaging (DTI) with a 7.0 T magnetic resonance imaging (MRI) scanner following chronic alcohol administration to explore new indicators for the early diagnosis and treatment of chronic alcoholism. Methods: Forty male Sprague-Dawley rats were randomly divided into the EtOH and control groups (water group). To establish a chronic alcohol administration rat model, rats were intragastrically administered edible wine (56% vol/vol) twice daily for four weeks. Quantitation of the changes in metabolite concentrations and the apparent diffusion coefficient (ADC), as well as the fractional anisotropy (FA) values, within the pontine of brain stem were detected using MRS and DTI at 7.0 T. Differences of the pontine metabolite content, ADC and FA values between the two groups were compared. Results: The 7.0 T MRIs showed no abnormal T2 phase pontine signals in either the EtOH or control groups. A 1H-MRS scan showed that the values for NAA, Cr and Cho in the EtOH group (4.54 ± 0.69, 4.69 ± 0.70 and 1.32 ± 0.18) were lower than those in the controls (6.78 ± 0.76, 8.50 ± 0.83 and 1.89 ± 0.24) (P < 0.01). However, the Glu+Gln values did not significantly differ between the controls (8.11 ± 1.11) and the EtOH group (7.31 ± 0.85) (P > 0.05). DTI showed that the FA value in chronic alcohol exposure rats (0.41 ± 0.12) was lower than the control rats (0.53 ± 0.08) (P < 0.05). However, the difference in the ADC values was not significant between the controls (0.0014 ± 0.00050) and the EtOH group (0.0012 ± 0.00027) rats (P > 0.05). Conclusions: After chronic alcohol exposure for four weeks, the metabolite content and axonal fibre changes in the rat pontine can be detected using MRS and DTI at 7.0 T earlier than conventional MRI, which provides information for the early diagnosis and treatment of chronic alcoholism. Short Summary: In the present study, the authors showed that the metabolite content and axonal fibre changes in the pontine of chronic ethanol-treated rats can be detected using MRS and DTI at 7.0 T earlier than conventional MRI, which provide objective indicators for the early diagnosis and treatment of chronic alcoholism.