Neuroprotective effect of Rosuvastatin on the entorhinal cortex of rats subjected to chronic sleep restriction

• Grant number: 24/23734-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2025
• End date: December 31, 2025
• Field of knowledge: Biological Sciences - Pharmacology - Neuropsychopharmacology
• Principal Investigator: José de Anchieta de Castro e Horta Júnior
• Grantee: Ygor Manata Jacobina
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Sleep can be defined as a natural, inherent, and reversible behavioral state characterized by reduced responsiveness to external stimuli. Despite being vital for physiological and cognitive regulation, in a society marked by the overvaluation of profit and productivity, sleep has come to be perceived as a dispensable dormant state. Combined with other repercussions of modern life, chronic sleep restriction has become increasingly common. Chronic sleep restriction leads to widespread consequences for the consolidation process that integrates newly encoded memory into long-term storage. The entorhinal cortex (EC) is an input-output structure originating in the parahippocampal region (PHR) and projecting to the hippocampal formation (HF), playing a key role in memory consolidation.Statins are drugs that reduce cellular cholesterol levels, with rosuvastatin being the most potent among them. This class of drugs is known for its pleiotropic potential, including protective actions on the nervous system. The present study aims to explore the pleiotropic effects of rosuvastatin on the nervous system and identify potential neuroprotective mechanisms against stress caused by chronic sleep restriction through behavioral and morphological analyses.Sixty male Wistar rats were used, divided into four groups (n=15). All experimental protocols were approved by the Ethics Committee on the Use of Animals of the Botucatu Medical School (CEUA-1414/2022). The groups were organized as follows: control group (CG), receiving the vehicle (200 mg of whipped cream + 30 µL of water) without sleep restriction; deprivation group (DG), receiving the vehicle with daily sleep restriction; and rosuvastatin groups (RG), which received daily single doses of 20 mg/kg (RG+) or 4.2 mg/kg (RG¿) of the drug administered with the vehicle. Pharmacological interventions were conducted for the same duration and concurrently with sleep restriction. The method used for sleep deprivation was the modified multiple platform technique. The sleep deprivation protocol was performed daily from 2:00 PM to 8:00 AM (light cycle: 5:00 AM to 5:00 PM) for 45 consecutive days. Rosuvastatin was administered to the animals once a day at 8:00 AM.The behavioral test employed was the Barnes Maze, initiated on the 23rd day of the protocol, corresponding to the peak action period of rosuvastatin. The protocol consisted of three daily exposures with 10-minute intervals between each exposure over five days, with the escape box placed in a novel location each day to assess working memory. On the final day of behavioral testing, the animals were euthanized, and seven animals from each group underwent the transcardiac perfusion protocol. Afterward, the brains were collected and subjected to cryostat sectioning.For the study of FOS protein expression through immunohistochemistry, the brains of six animals from each experimental group were selected and mounted on glass slides. Morphological evaluation focused on the lateral and medial entorhinal cortex regions, with image capture and immunoreactive cell counting. Seven coronal levels, regularly spaced from ¿3.12 mm to ¿7.56 mm relative to bregma, were analyzed. The results of all quantitative variables will be statistically compared and analyzed. Based on previous studies in the literature, it is expected that animals in the DG will exhibit poorer memory performance in behavioral tests and lower neuronal activation compared to the CG. Additionally, it is anticipated that the animals in the RG+ and RG¿ groups will demonstrate better behavioral and morphological outcomes than the DG group, with values closer to those found in the CG.