Melatonin does not produce sedation in rats: A chronobiological study

ABSTRACT

Background: Melatonin has been associated with a wide variety of cellular, neuroendocrine, and neurophysiological processes. Clinical studies have reported the use of melatonin as an agent that exerts sedative-hypnotic effects. However, evidence of the sedative-hypnotic effects of different doses of melatonin is inconsistent, and available data regarding its night/day-time sedative effects are limited. The purpose of this study was to evaluate the effects of melatonin administered at different times of day on the magnitude of the sedative-hypnotic activity of different melatonin doses (5, 10, 30, and 50 mg/kg) in rats.

Methods: Sedation was assessed in Wistar rats behaviorally, using rota-rod, spontaneous locomotor activity, and fixed-bar tests at different times of day (ZT4, ZT10, ZT16, and ZT22).

Results: Our results showed that, compared to trazodone, acute and chronic dosing of ≤5 mg melatonin produced mild, transient sedative effects, mainly in the light period. Nevertheless, doses of ≥10 mg/kg did not cause sustained sedative effects.

Conclusion: These results suggest that melatonin may be used for sedation induction, mainly in preoperative patients.

KEYWORDS:

• Melatonin
• sedation
• depression
• dosing schedules
• pharmacotherapy

Acknowledgments

Funding for this study was provided through grants INP-2000-2040 and CI-IC092020.2 and by CONADIC and the Gonzalo Ríos Arronte Foundation.

Disclosure statement

The authors declare that there are no conflicts of interest.

Authorship Contributions

Participated in research design: Alberto Salazar-Juárez.

Conducted experiments: Alberto Salazar-Juárez and Susana Barbosa Méndez.

Performed data analysis: Alberto Salazar-Juárez.

Wrote or contributed to the writing of the manuscript: Alberto Salazar-Juárez.

Additional information

Funding

This work was supported by the INP [INP-2000-2040 and CI-IC092020.2].