en Nervous system (others) Others Experimental research article Experimental research article <div style="text-align: justify;"><strong>Introduction:</strong> The dorsomedial periaqueductal gray (dmPAG) is located around the cerebral aqueduct with various functions such as cardiovascular regulation and is affected by inflammation. Lipopolysaccharide (LPS) is a complex molecule with an inflammatory effect that is known to affect blood pressure. In the present study, the cardiovascular effect of LPS microinjection into the dmPAG was investigated. <strong>Methods:</strong> Rats were divided into three groups consisting of 1: control; 2: 50 ng LPS and 3:100 ng LPS. Rats were mounted on a stereotaxic device after anesthesia and a continuous recording of cardiovascular parameters was done by a PowerLab device, connected to a cannulated femoral artery and drugs microinjected into dmPAG. The changes (&Delta;) in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MA) and heart rate (HR) were calculated at different times and compared to the control group. <strong>Results:</strong> Both doses of LPS when microinjected into the dmPAG brought on a significant hypotensive response in the pressure parameters (MAP, SBP, and DBP) when compared to control. A non-significant increase in HR was also documented in both groups. <strong>Conclusion: </strong>The results of this experiment indicated that LPS, when microinjected into the dmPAG, induced a hypotensive response in anesthetized rats in both doses in comparison to control.</div> Dorsomedial periaqueductal gray, Lipopolysaccharide, Inflammation, Blood Pressure 334 340 http://ppj.phypha.ir/browse.php?a_code=A-10-1463-1&slc_lang=en&sid=1 Reza Mohebbati 3200319475328460029335 3200319475328460029335 No Applied Biomedical Research Center, Mashhad University of Medical Sciences, Mashhad, Iran Reza Nejad Shahrokh Abadi 3200319475328460029336 3200319475328460029336 No Research Committee, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Vida Alikhani 3200319475328460029337 3200319475328460029337 No Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Mohammad Naser Shafei shafeimn@mums.ac.ir 3200319475328460029338 3200319475328460029338 Yes Applied Biomedical Research Center, Mashhad University of Medical Sciences, Mashhad, Iran