Une analyse approfondie de la fonction hippocampique pour révéler les endophénotypes diurne/nocturne
Swiss partners
- Université de Genève: Benjamin B. Tournier (main applicant), Aurélien Badina
Partners in the MENA region
- Université Sultan Moulay Slimane, Morocco: Ibtissam Chakir (main applicant),Hamza Zahiri, Ali Ouarour
Presentation of the project
Our biological functions, such as memory, sleep, and hormone production, follow a regular 24-hour rhythm known as the circadian rhythm. This rhythm is controlled by an internal clock located in a small brain region called the suprachiasmatic nuclei (SCN) of the hypothalamus. These neurons naturally oscillate on a roughly 24-hour cycle, even in the absence of light. To stay synchronized with the external world, this clock adjusts mainly through the day/night alternation detected by the eyes, then transmits timing signals to the rest of the body via neural and hormonal pathways. In both diurnal and nocturnal animals, Clock genes in the SCN show broadly similar expression cycles. Differences between species therefore arise not from the central clock itself, but from how other brain regions interpret its signals. As a result, certain hormones (like melatonin) and cognitive functions (such as memory) show opposite phases depending on whether the species is active by day or by night. Moreover, disruptions in circadian rhythms are commonly observed in neurological disorders such as Alzheimer’s disease. One brain region strongly involved in memory and Alzheimer’s disease is the hippocampus. Our research project aims to understand how hippocampal functions differ between day and night, between nocturnal and diurnal rodents, and to identify alterations of these cycles in a mouse model of Alzheimer’s pathology.
To support this project, a workshop on “Behavioral and functional explorations in rodents” was held on May 20th, 2024, at the University of Tangier, followed by a half-day conference on May 21th at the University of Tetouan (see photo). During this event, the Swiss partners presented a lecture entitled “Analysis of glial dysfunction in Alzheimer’s disease: from cell culture to humans.” These meetings also provided an opportunity for both teams to coordinate experimental preparations at the University of Tetouan using the diurnal rodent species Lemniscomys barbarus, where analyses are still ongoing. In Switzerland, studies on day/night variations in the proteome of nocturnal mice and alterations linked to Alzheimer’s disease are currently being finalized for publication. Preliminary results show that energy metabolism and astrocyte activity are the two most strongly affected markers.