The impact of different dark chocolate dietary patterns on synaptic potency and plasticity in the hippocampal CA1 area of the rats under chronic isolation stress

ABSTRACT

Introduction

Although, stress causes brain dysfunction, consumption of dark chocolate (DC) has positive effects on brain functions. The current study investigated the impact of different DC dietary patterns on synaptic potency and plasticity in the hippocampal CA1 area, as well as food intake and body weight in rats under chronic isolation stress.

Methods

Thirty-five rats were allocated into five groups of control, stress, and stress accompanied by three DC dietary patterns (stress-compulsory, -optional, and -restricted DC). The stressed rats on a compulsory diet only received DC and the ones on an optional diet received unlimited chow and/or DC. Also, the stressed rats on a restricted diet each received chow freely and only 4 g DC daily. Subsequently, the slope and amplitude of field excitatory postsynaptic potentials (fEPSPs) were assessed based on the Input-Output (I/O) curves and after the longterm potentiation (LTP). Moreover, food intake and body weight were measured for all groups.

Results

The fEPSP slope and amplitude in the I/O curves and after LTP decreased significantly in the stress group compared to the control group. Although the slope and amplitude both enhanced non-significantly in the optional DC diet, these parameters changed significantly in both compulsory and restricted DC dietary patterns compared to the stress group. Also, food intake and body weight decreased significantly in all DC groups.

Conclusion

The compulsory and restricted DC dietary patterns reversed the harmful effects of chronic isolation stress on the hippocampal synaptic potency, plasticity, learning, and memory. All DC diets, especially compulsory and restricted ones, reduced food intake and body weight.

KEYWORDS:

• CA1
• synaptic potency
• stress
• long-term potentiation
• dark chocolate
• body weight
• hippocampus
• memory

Acknowledgements

The conduction of this research was made possible by the support of Isfahan University of Medical Science, Isfahan, Iran. Also, the present study obtained a grant from the Isfahan University of Medical Sciences (Isfahan, Iran).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethical statement

All experiments were approved by the Research and Ethics Committee of Isfahan University of Medical Sciences (IR.MUI.MED.REC.1398.036); the research proposal was accepted in 2019.

Additional information

Funding

This work was supported by the Isfahan University of Medical Sciences, Isfahan, Iran.

Notes on contributors

Elham Kalantarzadeh

Ehham Kalantarzadeh, MSc of physiology, Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.

Maryam Radahmadi

Maryam Radahmadi, Associate of professor in physiology, Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.

Parham Reisi

Parham Reisi, Professor in physiology, Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.