The effects of black garlic on the working memory and pyramidal cell number of medial prefrontal cortex of rats exposed to monosodium glutamate

Abstract

Monosodium glutamate-induced exitotoxicity causes oxidative stress in many brain areas, including the medial prefrontal cortex. The ethanolic garlic (Allium sativum) extract is considered as a neuroprotective substance. The present study aimed at investigating the effects of the ethanolic fermented garlic extract on the working memory and the pyramidal cell number of the medial prefrontal cortex of adolescent male Wistar rats exposed to monosodium glutamate (MSG). Twenty-five rats were randomly divided into five groups. The C– group was given 0.9% NaCl solution. The C + group was given 2 mg/g bw of MSG. The T1, T2, and T3 groups were given MSG and garlic extract (0.0125, 0.025, and 0.05 mg/g bw, respectively). All treatments were conducted for 10 days. The working memory capability of the rats was measured using Y-maze test. The total number of pyramidal cells of the medial prefrontal cortex was estimated using physical fractionator method. The working memory performances of the T1, T2, and T3 groups were significantly better than that of the C + group. There were no significant differences between groups in the estimated total number of pyramidal cell of medial prefrontal cortex. The MSG may not cause the death of neurons, but it may modify neuronal architectures that are sufficient to disrupt memory functions. Black garlic may play a role as an antioxidant agent that prevents the prefrontal cortex from glutamate-induced oxidative stress. It is concluded that the ethanolic fermented garlic extract prevented the working memory impairment following MSG administration.

Keywords:

• Working memory
• medial prefrontal cortex
• monosodium glutamate
• Allium sativum

Acknowledgements

This manuscript is a part of Titis Nurmasitoh’s thesis. The authors would like to extend their gratitude to M. Aminuddin, Ery Hermawati, Suparno (Department of Physiology, Faculty of Medicine, UGM), and Sumaryati (Department of Histology, Faculty of Medicine, UGM) for providing technical assistance.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Universitas Gadjah Mada [grant no. LPPM UGM/700/BID.I/2012].