Adenosine A1 and A2a receptor protein expression in cerebral blood vessels of Sprague-Dawley rats exposed to hyperbaric oxygen

*Corresponding authors: Aleksandar Kibel, MD, PhD. Email: alekibel@mefos.hr Zrinka Mihaljević, PhD. E-mail: zmihaljevic@mefos.hr Introduction: Hyperbaric oxygenation (HBO2) affects gene and protein expression, modulate signaling pathways and influence vascular structure and function .Adenosine receptors (AR) play an important role in the mechanism of action of oxygen as a signaling molecule and vasoactive substance, and their expression may be affected by HBO2. Objecitve: Present study aimed to determine the protein expression of adenosine A1 and A2a receptor in cerebral blood vessels of Sprague- Dawley rats after exposure to acute and intermittent HBO2. Methods: Male and femal healthy Sprague-Dawley rats aged 8-10 weeks were divided into 3 groups: CTRL (control non HBO2), A-HBO2 (animals exposed to single HBO2 for 2 hours) and 4D-HBO2 (animals exposed to HBO2 at a pressure od 2 bars for 2 hours daily for 4 days, with sample collection on the fifth day). Superficial brain blood vessels were collected to determine the protein expression of adenosine A1 and A2a receptors using the Western blot method. All experimental procedures conformed to the European Guidelines for the Care and Use of Laboratory Animals (directive 86/609) and were approved by the local and national Ethical Committee (#2158-61-07-21-88 ; EP-348/2021) Results: A1 receptor protein expression was significantly reduced in A-HBO2 rats compared to 4D-HBO2 (relative expression in relation to β- actin 0.5865 +/- 0.1259 vs 0.9316 +/- 0.1152, p=0.0191). A-HBO2 group had significantly reduced protein expression of A2a receptors compared to CTRL (0.2380 +/- 0.09028 vs 0.6833 +/- 0.1054, p