Orchestration of the circadian clock and its association with Alzheimer's disease: Role of endocannabinoid signaling

Deepak Kumar, Ashish Sharma, Rajeev Taliyan, Maiko T. Urmera, Oscar Herrera-Calderon, Thomas Heinbockel, Shafiqur Rahman, Rohit Goyal

Research output: Contribution to journalReview articlepeer-review

1 Scopus citations

Abstract

Circadian rhythms are 24-hour natural rhythms regulated by the suprachiasmatic nucleus, also known as the "master clock". The retino-hypothalamic tract entrains suprachiasmatic nucleus with photic information to synchronise endogenous circadian rhythms with the Earth's light-dark cycle. However, despite the robustness of circadian rhythms, an unhealthy lifestyle and chronic photic disturbances cause circadian rhythm disruption in the suprachiasmatic nucleus's TTFL loops via affecting glutamate and γ-aminobutyric acid-mediated neurotransmission in the suprachiasmatic nucleus. Recently, considerable evidence has been shown correlating CRd with the incidence of Alzheimer's disease. The present review aims to identify the existence and signalling of endocannabinoids in CRd induced Alzheimer's disease through retino-hypothalamic tract- suprachiasmatic nucleus-cortex. Immunohistochemistry has confirmed the expression of cannabinoid receptor 1 in the suprachiasmatic nucleus to modulate the circadian phases of the master clock. Literature also suggests that cannabinoids may alter activity of suprachiasmatic nucleus by influencing the activity of their major neurotransmitter γ-aminobutyric acid or by interacting indirectly with the suprachiasmatic nucleus's two other major inputs i.e., the geniculo-hypothalamic tract-mediated release of neuropeptide Y and serotonergic inputs from the dorsal raphe nuclei. Besides, the expression of cannabinoid receptor 2 ameliorates cognitive deficits via reduction of tauopathy and microglial activation. In conclusion, endocannabinoids may be identified as a putative target for correcting CRd and decelerating Alzheimer's disease.

Original languageEnglish
Article number101533
JournalAgeing Research Reviews
Volume73
DOIs
StatePublished - Jan 2022

Bibliographical note

Funding Information:
This publication resulted in part from research support to T.H. from the National Science Foundation [ NSF IOS-1355034 ], Howard University College of Medicine , and the District of Columbia Center for AIDS Research, an NIH funded program [ P30AI117970 ], which is supported by the following NIH Co-Funding and Participating Institutes and Centers: NIAID, NCI, NICHD, NHLBI, NIDA, NIMH, NIA, NIDDK, NIMHD, NIDCR, NINR, FIC and OAR. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

  • Alzheimer's disease
  • Circadian rhythm
  • Endocannabinoid system
  • Retina
  • Suprachiasmatic nucleus

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