en Neurophysiology/Pharmacology Neurophysiology/Pharmacology Experimental research article Experimental research article <p style="text-align:justify"><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif"><strong>Introduction: </strong>The cardiovascular effect of the pedunculopontine tegmental nucleus (PPT), a mesencephalic area, has been evaluated. Due to the presence of the GABAB receptor of GABAergic system in the PPT, this study has investigated the possible cardiovascular effect of this receptor in the PPT and has compared it with GABAA. </span></span></p> <p style="text-align:justify"><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif"><strong>Methods: </strong>Rats randomly were divided into control, two doses of 0.5 and 1 nmol of Baclofen (GABAB receptor agonist), 0.5 and 1 nmol, of Phaclofen (GABAB receptor antagonist) and two doses of 0.1 and 0.2 nmol of Bicuculline (BMI, GABAA receptor antagonist) and co-injection of Phaclofen (1nmol)+ Bicuculline (0.2 nmol) groups. After anesthesia, a heparinized polyethylene catheter was placed in the femoral artery and was connected to a pressure transducer cardiovascular response was recorded by a Power lab device. Then the systolic blood pressure (SBP), mean arterial pressure (MAP) and heart rate (HR) were continuously recorded. The injection of drugs into the PPT was done stereotaxically. Cardiovascular changes (&Delta;,difference between pre and post-injection) induced by drug were calculated and analyzed. </span></span></p> <p style="text-align:justify"><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif"><strong>Results:</strong> Injection of both doses of Baclofen and Phaclofen did not induce significant changes in MAP, SBP, and HR. Injection of both doses of BMI significantly increased &Delta;MAP, &Delta;SBP, and &Delta;HR than control group. Injection of Phaclofen (1nmol) and BMI (0.2 nmol) could increase &Delta;MAP, &Delta;SBP, and &Delta;HR that was non-significant than Phaclofen alone. </span></span></p> <p style="text-align:justify"><span style="font-size:12px"><span style="font-family:Arial,Helvetica,sans-serif"><strong>Conclusion: </strong>We found that GABAB receptors of the PPT were not involved in cardiovascular activity and this effect was mainly mediated through GABAA receptors.</span></span></p> Mean arterial pressure,Heart rate,Pedunculopontine tegmental nucleus,GABA,Bicuculine 54 62 http://ppj.phypha.ir/browse.php?a_code=A-10-2287-1&slc_lang=en&sid=1 Mohammad Naser Shafei ShafeiMN@mums.ac.ir 3200319475328460036990 3200319475328460036990 No Applied Biomedical Research center, Mashhad University of Medical Science, Mashhad, Iran Division of Neurocognitive Sciences, Psychiatry and Behavioral Sciences Research Center, Mashhad University of Medical Science, Mashhad, Iran Hossein Pasandi pasandih1@mums.ac.ir 3200319475328460036991 3200319475328460036991 No Department of Physiology, Medicine School, Mashhad University of Medical Science, Mashhad, Iran Vida Alikhani alikhaniv4013@mums.ac.ir 3200319475328460036992 3200319475328460036992 Yes Department of Physiology, Medicine School, Gonanbad University of Medical Science, Gonabad, Iran