Role of ventral hippocampal GABA(A) and NMDA receptors in the anxiolytic effect of carbamazepine in rats using the elevated plus maze test.

BACKGROUND: The successful use of antiepileptic drugs to treat a wide range of nonepileptic disorders led us to evaluate the potential efficacy of carbamazepine (CBZ) in anxiety disorders. Anxiety may be related to the imbalance between gamma-aminobutyric acid (GABA) and glutamate neurotransmitters, systems that are also involved in the CBZ effects. We investigated the role of these systems in the ventral hippocampus (VH) and their interactions with the CBZ effect on anxiety-like behavior in rats using the elevated plus maze. METHODS: Animals received GABAergic and NMDA agents in a volume of 1 microl/rat, which was injected into the VH (0.5 microl for each side) 60 min after receiving systemic administration of CBZ. The test sessions took place 10 min later. RESULTS: The systemic administration of CBZ increased the percentage of open arm time (%OAT) at the dose of 40 mg/kg, which is representative of an anxiolytic response. Intra-VH injection of the GABA(A) receptor agonist muscimol (0.25-1 microg/rat) in the absence or presence of an ineffective dose of CBZ (30 mg/kg) did not show any significant changes in the parameters of anxiety-like behavior. The administration of GABA(A) receptor antagonist bicuculline by itself decreased %OAT at a dose of 1 microg/rat, indicating possible anxiogenic effect. The antagonist (0.75 and 1 microg/rat) also decreased CBZ response. A microinjection of NMDA (0.125 and 0.25 microg/rat) decreased %OAT, which was reversed by the administration of CBZ (40 mg/kg). This indicates interaction between the two drugs. However, the NMDA receptor antagonist DAP-5 (1 microg/rat) significantly increased %OAT, but combined with the lower dose of CBZ (30 mg/kg), it did not trigger any response on anxiety-like parameters. CONCLUSION: Both GABAergic and NMDA systems in the VH play a role in modulation of anxiety-like behavior of rats. The anxiolytic-like effects of CBZ seem to be mediated, at least in part, through an interaction with GABA(A) and NMDA systems in the VH.

Randomized Trial of Carnitine for the Prevention of Perioperative Atrial Fibrillation.

Atrial fibrillation (AF) is one of the most common complications in patients who undergo coronary artery bypass graft surgery (CABG). The aim of this study was to evaluate the effect of L-carnitine administration on postoperative AF and the levels of C-reactive protein (CRP) following CABG. The effects of L-carnitine on the incidence of acute kidney injury after CABG were also assessed. One hundred thirty-four patients undergoing elective CABG, without a history of AF or previous L-carnitine treatment, were randomly assigned to an L-carnitine group (3000 mg/d L-carnitine) or a control group. CRP levels, as a biomarker of inflammation, were assessed in all the patients before surgery as baseline levels and 48 hours postoperatively. Neutrophil gelatinase-associated lipocalin, as a kidney biomarker, was also measured in the patients before surgery and 2 hours thereafter. The incidence of AF was 13.4% in our population. The incidence of AF was decreased in the L-carnitine group (7.5% in the L-carnitine group vs 19.4% in the control group; P = 0.043) and the postoperative CRP level (8.79 ± 6.9 in the L-carnitine group, and 10.83 ± 5.7 in the control group; P = 0.021). The postoperative neutrophil gelatinase-associated lipocalin concentration demonstrated no significant rise after surgery compared with the preoperative concentration (72.54 ± 20.30 in the L-carnitine group vs 67.68 ± 22.71 in the placebo group; P = 0.19). Our study showed that L-carnitine administration before CABG might inhibit and reduce the incidence of AF after CABG. It seems that a rise in the CRP level, as an inflammation marker, may be associated with the incidence of AF. Inflammation as measured by CRP was also reduced in the carnitine group, compared with the control group.

Preoperative Hemoglobin A1c and the Occurrence of Atrial Fibrillation Following On-pump Coronary Artery Bypass Surgery in Type-2 Diabetic Patients.

BACKGROUND: We investigated the association of the preoperative hemoglobin A1c (HbA1c) with occurrence of postoperative atrial fibrillation (POAF) in type-2 diabetic patients who underwent isolated coronary artery bypass grafting. METHODS: We prospectively studied 708 type-2 diabetes patients [433 men ([61.2%)], candidate for isolated coronary artery bypass grafting. Biochemistry profile was measured on the day of operation. All patients were telemonitored for 72 hours after operation for the occurrence of atrial fibrillation. The role of HbA1c as a predictor for the occurrence of atrial fibrillation was then evaluated. RESULTS: A total of 109 (15.3%) patients developed POAF. Patients in the atrial fibrillation group tended to be older, with prolonged longer diabetes, and have renal failure, chronic obstructive pulmonary disease, and hypertension. In the univariable and multivariable regression model, HbA1c was not a predictor for POAF. CONCLUSIONS: Serum level of HbA1c could not be used as a predictor for the development of POAF.

Permcath catheter embolization: a case report.

INTRODUCTION: Nowadays, many types of intravascular devices and catheters are used in order to diagnose and treat diseases. Complications related to these instruments are the costs that doctors and patients have to pay to benefit from their advantages. Catheter embolization is one of these side effects. Patients with devices in their cardiopulmonary system are at risk for severe complications such as arrhythmias, pulmonary embolism, myocardial injuries, hemoptysis, thrombosis and perforation. CASE PRESENTATION: A 50-years-old woman, with a history of breast cancer, had a PermCath emplacement in right subclavian vein for a course of chemotherapy. The treatment for cancer seemed to be successful and the PermCath had remained in its position without complication, for a couple of years however, the catheter was founded broken and embolized to the right ventricle and the main left pulmonary artery, diagnosed by a chest X-ray study incidentally. CONCLUSIONS: It is better to remove the unused devices safely to prevent and decrease their possible complications.

Preoperative oral pentoxifylline in case of coronary artery bypass grafting with left ventricular dysfunction (ejection fraction equal to/less than 30%).

OBJECTIVE: Most coronary artery bypass grafts are done by applying cardiopulmonary bypass, which usually induces unwanted inflammatory reactions and impairs the outcomes. In order to minimize the perilous response of cardiopulmonary bypass, pentoxifylline was getting used orally. METHODS: In a prospective, placebo-controlled, randomized clinical trial, 178 coronary artery bypass graft candidates with ejection fraction lower/equal to 30%, divided into two equal groups (pentoxifylline and control), participated in the study. Pentoxifylline patients received 400 mg pentoxifylline 3 times a day for 3 days before operation. The outcomes were compared between groups using student's t-test, Mann-Whitney U-test, Pearson chi-square, or Fisher's exact test. RESULTS: Pentoxifylline administration did not significantly affect troponin-T (p=0.68), but it reduced tumor necrosis factor-α (p=0.01) and interleukin-6 (p=0.01). It improved left ventricular ejection fraction significantly (p=0.01). White blood cell and platelet counts, hemoglobin, and hematocrit were not influenced by pentoxifylline. The drug did not affect blood urea nitrogen and creatinine, occurrence of renal failure, cerebrovascular accidents, and in-hospital mortality rate. The need for an intra-aortic balloon pump, cardiopulmonary bypass, and aortic cross-clamp times were not affected, either. Pentoxifylline decreased the intensive care unit stay (p<0.001), ventilation time, 10.4 hours in the pentoxifylline group against 14.7 hours in the control group (p=0.01), and the requirement of inotropic agents (p=0.02) and blood transfusion (p=0.01). CONCLUSION: Pentoxifylline has more beneficial potencies in reducing adverse events after coronary artery bypass graft using cardiopulmonary bypass, than what are known.

Transseptal Approach versus Left Atrial Approach to Mitral Valve: A Propensity Score Matching Study.

BACKGROUND: Many patients with mitral valve diseases need surgical procedures for the repair or replacement of their mitral valve. There is a great deal of controversy over the outcomes of the transseptal (TS) and left atrial (LA) approaches to the mitral valve. We sought to evaluate the outcomes of each approach more accurately by eliminating the possible biases in case selection and matching. METHODS: This retrospective study included patients who had surgery for mitral valve diseases via either the TS approach or the LA approach between 2004 and 2011 in Tehran Heart Center. Patients with surgical approaches other than the TS and LA were excluded. To control for the confounding effects, a propensity score matching technique was applied and the patients were matched for 14 demographic and preoperative variables. After the selection of controls, the effect of the TS approach (163 patients) versus the LA approach (652 patients) on the outcomes was presented through odds ratio (OR) with 95% confidence intervals (CI). RESULTS: The mean age of the patients was 53.15 ± 12.02 years in the TS group and 52.93 ± 13.56 years in the LA group. Females comprised 119 (73.0%) patients in the TS group and 462 (70.9%) in the LA group. There was a significant association in the prevalence of new postoperative atrial fibrillation in the two groups (OR = 1.539, 95%CI: 1.072-2.210; p value = 0.019). Temporary pacemaker placement had no statistically significant difference between the two groups (p value = 0.418). The TS patients had significantly longer pump (p value < 0.001) and cross-clamp (p value < 0.001) times. The mortality rate was 4.1% (27 patients) in the LA group and 6.1% (10 patients) in the TS group (p value = 0.274). CONCLUSION: In our study population, the TS approach was associated with higher pump and cross-clamp times as well as risk of postoperative atrial fibrillation, but it did not increase the rates of permanent pacemaker placement, re-operations, and mortality.

Potential Effect of L-Carnitine on the Prevention of Myocardial Injury after Coronary Artery Bypass Graft Surgery.

BACKGROUND: L-carnitine has been demonstrated to confer cardiac protection against ischemia reperfusion injury in animals. This study evaluates the effects of L-carnitine administration on cardiac biomarkers after coronary artery bypass graft (CABG) surgery. METHODS: One hundred thirty-four patients undergoing elective CABG surgery, without a history of myocardial ischemia or previous L-carnitine treatment, were enrolled and randomly assigned to an L-carnitine group ([n = 67], 3000 mg/d, started 2 days preoperatively and continued for 2 days after surgery) or a control group (n = 67). CK-MB (creatine kinase, muscle-brain subunits) and troponin T (TnT) levels were assessed in all the patients before surgery as baseline levels and at 8 and 24 hours postoperatively. RESULTS: Our study included 134 patients (99 [73.8%] males) at a mean ± SD age of 59.94 ± 8.61 years who were candidates for CABG and randomized them into control or L-carnitine groups. The baseline demographic characteristics, including age (60.01 ± 9.23 in the L-carnitine group vs. 59.88 ± 7.98 in the control group) and sex (54 [80.6%] in the L-carnitine group vs. 45 [67.2%] in the control group) did not show any significant differences (p value=0.93 and 0.08, respectively). Patients in the L-carnitine group had lower levels of CK-MB (mean ± SD, 25.06 ± 20.29 in the L-carnitine group vs. 24.26 ± 14.61 in the control group), but the difference was not significant (p value = 0.28). TnT levels also showed no significant differences between the two groups (399.50 ± 378.91 in the L-carnitine group vs. 391.48 ± 222.02 in the control group; p value = 0.34). CONCLUSION: In this population of intermediate- to high-risk patients undergoing CABG surgery, L-carnitine did not reduce CK-MB and TnT levels.

Association between Perioperative Parameters and Cognitive Impairment in Post-Cardiac Surgery Patients.

BACKGROUND: Postoperative cognitive dysfunction (POCD) has been an important complication of cardiac surgery over the years. Neurocognitive dysfunction can affect quality of life and lead to social, functional, emotional, and financial problems in the patient's life. To reduce POCD, we sought to identify the association between cognitive dysfunction and perioperative factors in patients undergoing cardiac surgery. METHODS: One hundred one patients aged between 45 and 75 years undergoing elective cardiac surgery were enrolled in this study. All the surgeries were performed on-pump by the same medical team. A brief Wechsler Memory Test (WMT) was administered before surgery, 3 to 5 days after the surgery, and 3 months after discharge. All related perioperative parameters were collected in order to study the effect of these parameters on the postoperative WMT scores and WMT score change. RESULTS: The study population consisted of 101 patients, comprising 14 (13.8%) females and 87 (86.2%) males aged between 45 and 75 years. In univariate analysis, the baseline WMT score, serum levels of lactate dehydrogenase and T3, cross-clamp time, and preexistence of chronic obstructive pulmonary disease showed significant effects on the postoperative WMT score (p value < 0.05), whereas only the baseline WMT score and chronic obstructive pulmonary disease showed strong effects on the postoperative WMT score in the multiple regression model. In addition, the multiple regression model demonstrated a significant association between the baseline WMT score, serum creatinine level, and nitrate administration and the WMT score change. CONCLUSION: Our study showed that preexisting chronic obstructive pulmonary disease and preoperative high serum creatinine levels negatively affected cognitive function after surgery. In addition, there was a strong relationship between the patients' basic cognition and POCD. Preoperative nitrate administration led to a significant improvement in POCD. It is also concluded that the preoperative administration of specific medicines like nitrates can reduce neurological complications after cardiac surgery.

Anxiolytic-Like Effects and Increase in Locomotor Activity Induced by Infusions of NMDA into the Ventral Hippocampus in Rat: Interaction with GABAergic System.

INTRODUCTION: In this study, we investigated the role of N-Methyl-D-Aspartate (NMDA) receptors in the ventral hippocampus (VH) and their possible interactions with GABAA system on anxiety-like behaviors. METHODS: We used an elevated-plus maze test (EPM) to assess anxiety-like behaviors and locomotor activity in male Wistar rats. RESULTS: The results showed that intra-VH infusions of different doses of NMDA (0.25 and 0.5 µg/rat) increased locomotor activity, and also induced anxiolytic-like behaviors, as revealed by a tendency to increase percentage of open arm time (%OAT), and a significant increase in percentage of open arm entries (%OAE). The results also showed that intra-VH infusions of muscimol (0.5 and 1 µg/rat) or bicuculline (0.5 and 1 µg/rat) did not significantly affect anxiety-like behaviors, but bicuculline at dose of 1 µg/rat increased locomotor activity. Intra-VH co-infusions of muscimol (0.5 µg/rat) along with low doses of NMDA (0.0625 and 0.125 µg/rat) showed a tendency to increase %OAT, %OAE and locomotor activity; however, no interaction was observed between the drugs. Interestingly, intra-VH co-infusions of bicuculline (0.5 µg/rat) along with effective doses of NMDA (0.25 and 0.5 µg/rat) decreased %OAT, %OAE and locomotor activity, and a significant interaction between two drugs was observed. DISCUSSION: It can be concluded that GABAergic system may mediate the anxiolytic-like effects and increase in locomotor activity induced by NMDA in the VH.

Hospital-acquired pneumonia in patients undergoing coronary artery bypass graft; comparison of the center for disease control clinical criteria with physicians' judgment.

BACKGROUND: Following coronary artery bypass graft (CABG), patients are at high risk (3.2%-8.3%) for developing hospital-acquired pneumonia (HAP) with mortality rate of 24% to 50%. Some of routine features in patients undergoing CABG are similar to clinical criteria of Center of Disease Control (CDC) for diagnosis of pneumonia. This may lead to over-diagnosis of pneumonia in these patients. OBJECTIVES: This study aimed to assess the frequency of CDC criteria for diagnosis of pneumonia in patients undergoing CABG. PATIENTS AND METHODS: This study was performed on CABG candidates admitted to post cardiac surgery Intensive Care Unit (ICU) in a six-month period. Patient's records, Chest-X-Ray, and Laboratory tests were assessed for PNU1-CDC criteria for HAP diagnosis. At the same time, a physician who was unaware of the study protocol assessed the clinical diagnosis. Then the results were compared with CDC criteria-based diagnosis. RESULTS: Of total 300 patients, 9 (3%) met CDC criteria for diagnosis of pneumonia while none of the cases were diagnosed as HAP according to the physicians' clinical diagnosis. All nine patients were discharged with proper general condition and no need of antibiotic therapy. This study showed that loss of consciousness, tachypnea, dyspnea, PaO2 < 60 mm Hg, PaO2/FiO2 < 240, and local infiltration in 24 hours of operation were misleading features of CDC criteria, which were not considered in physicians' clinical judgment to establish the diagnosis. CONCLUSIONS: Our findings suggest that in Post-CABG patients, physicians could judge the occurrence of HAP more accurately in comparison to making the diagnosis based on CDC criteria alone. Expert physician may intentionally do not take some of these criteria into account according the patients' course of disease. Therefore, it is suggested that the value of these criteria in special group of patients like those undergoing CABG should be re-evaluated.

Early outcome of off-pump versus on-pump coronary revascularization.

INTRODUCTION: The use of coronary artery bypass surgery (CABG) with cardiopulmonary bypass (CPB) or without CPB technique (off-pump) can be associated with different mortality and morbidity and their outcomes remain uncertain. The goal of this study was to evaluate the early outcome of on-pump versus off-pump CABG. METHODS: We conducted a retrospective database review of 13866 patients (13560 patients undergoing on-pump CABG and 306 patients undergoing off-pump CABG) at Tehran Heart Center between January 2002 and January 2007. We compared preoperative, operative, and postoperative characteristics between them. RESULTS: In-hospital mortality in the on-pump group was 0.8% compared to 0.7% in the off-pump group (P=0.999) and in-hospital morbidity was 11.7% and 6.5%, respectively (OR: 1.533, 95%CI: 0.902-2.605, P=0.114). Postoperative atrial fibrillation was more prevalent in on-pump versus off-pump surgery (6.0% vs 3.0%, P=0.028), however there were no statistical significant differences in other postoperative complications with regard to cardiac arrest (P=0.733), prolonged ventilation (P=0.363), brain stroke (P=0.999), renal failure (P=0.525), and postoperative bleeding (P=0.999). The mean length of stay in hospital (P=0.156) and in ICU (P=0.498) was also similar between the two groups. CONCLUSION: The results from an Iranian population-based study showed similar early mortality and morbidity of off-pump CABG in comparison to on-pump surgery.

Positive family history as the single traditional risk factor for developing extensive very premature coronary artery disease: a case report.

Although coronary artery disease (CAD) is not common among individuals younger than 40-45 years of age, a small percentage of this age group needs to undergo surgical revascularization because of CAD. Why some people are at higher risk of developing premature CAD is not clearly known. Increased number of traditional risk factors or genetic predisposition may play significant roles in this regard. A 22-year-old man with a negative history for all traditional risk factors except for a family history of premature CAD referred to our center due to an episode of myocardial infarction of one month's duration. He had no congenital heart disease and no hypercoagulable state, and there was a negative history of drug abuse. His coronary angiography showed extensive CAD. He underwent coronary artery bypass grafting and he left the hospital in good healthy condition. One year after surgery, his follow-up showed that he was symptom free and he still had no new traditional risk factor. It seems that a positive family history of premature CAD is an important and independent risk factor for developing premature CAD and individuals with this type of history should be treated more cautiously.

Ascending aorta aneurysm and blood group A among Iranian patients.

BACKGROUND: Ascending aortic aneurysm is a life threatening conditions leading to surgery in many cases. Demonstrating risk factors for this disease is essential for development of screening strategies for high-risk populations. Blood group although described as a potential risk factor for abdominal aortic aneurysm, has not been addressed in patients with aneurysm of the ascending aorta. OBJECTIVES: Our study aimed to demonstrate the prevalence of ABO blood groups among one of the largest Iranian population with diagnosed aneurysm of the ascending aorta. METHODS: A retrospective study was conducted in Tehran Heart Center in Tehran, Iran reviewing profile of 24,433 patients admitted to the cardiac surgery ward between January 2005 and February 2012 to extract data of 96 patients with confirmed diagnosis of ascending aortic aneurysm (AAA). Frequency of blood groups was determined and risk factors and AAA-related complications and mortality were compared between different blood groups. RESULTS: Of ninety six patients with AAA, 38 patients (39.58%) had blood group A, followed by 16 patients with blood group B (16.66%), 12 blood group AB (12.5%), and 30 patients (30.25%) with blood group O. Cerebrovascular accident (CVA), peripheral vascular disease (PVD), and AAA-related mortality were more frequent in patients with blood group A. However, it did not reveal statistically significant difference (p>0.05). CONCLUSION: Our study showed that risk factors for developing vascular disease are more prevalent in patients with blood group A and this blood group is associated with higher complication and mortality in AAA.

Impact of Angiotensin-converting enzyme inhibitors and Angiotensin receptor blockers on mortality of coronary artery bypass grafting.

BACKGROUND: There is controversy over the potential benefits/harms of the usage of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) as regards the postoperative mortality of coronary artery bypass grafting (CABG). This study investigates the correlation between the in-hospital mortality of CABG and the preoperative administration of ACEI/ARB. METHODS: Out of 10055 consecutive patients with isolated CABG from 2006 to 2009, 4664 (46.38%) patients received preoperative ACEI/ARB. Data were gathered from the Cardiac Surgery Registry of Tehran Heart Center. In-hospital mortality was defined as death within the same admission for surgery. Adjusted for confounders, multivariable logistic regression models were used to evaluate the impact of preoperative ACEI/ARB therapy on in-hospital death. RESULTS: The mean age of the patients was 60.04 ± 9.51 years and 7364 (73.23%) were male. Eighty-seven (0.86%) patients expired within 30 days. Multivariate analysis revealed that the administration of ACEI/ARB significantly protected against in-hospital deaths inasmuch as there were 33 (0.70%) vs. 54 (1.0%) deaths in the ACEI/ARB positive and negative groups, respectively (OR: 0.628; p value = 0.09). Patients without ACEI/ARB were more likely to have a higher global ejection fraction. CONCLUSION: Preoperative ACEI usage in patients undergoing CABG can be associated with decreased in-hospital mortality. Large-scale randomized clinical trials are suggested.

A New Method for Extubation: Comparison between Conventional and New Methods.

BACKGROUND: Extubation is associated with the risk of complications such as accumulated secretion above the endotracheal tube cuff, eventual atelectasia following a reduction in pulmonary volumes because of a lack of physiological positive end expiratory pressure, and intra-tracheal suction. In order to reduce these complications, and, based on basic physiological principles, a new practical extubation method is presented in this article. METHODS: The study was designed as a six-month prospective cross-sectional clinical trial. Two hundred fifty-seven patients undergoing coronary artery bypass grafting (CABG) were divided into two groups based on their scheduled surgery time. The first group underwent the conventional extubation method, while the other group was extubated according to a new described method. Arterial blood gas (ABG) analysis results before and after extubation were compared between the two groups to find the effect of the extubation method on the ABG parameters and the oxygenation profile. RESULTS: In all time intervals, the partial pressure of oxygen in arterial blood / fraction of inspired oxygen (PaO(2)/FiO(2)) ratio in the new method group patients was improved compared to that in the conventional method; some differences, like PaO(2)/FiO(2) four hours after extubation, were statistically significant, however (p value=0.0063). CONCLUSION: The new extubation method improved some respiratory parameters and thus attenuated oxygenation complications and amplified oxygenation after extubation.

The effect of a high dose of atorvastatin on the occurrence of atrial fibrillation after coronary artery bypass grafting.

BACKGROUND: Recent studies have suggested that statins reduce the incidence of atrial fibrillation (AF) after cardiac operations. Statin therapy at intensive doses, however, has yet to be thoroughly investigated. METHODS: We retrospectively studied 1,839 consecutive patients (1,177 men [73.2%]) who underwent isolated coronary artery bypass grafting and had no history of previous AF, pacemaker implantation, or antiarrhythmic medication. Data recorded included the atorvastatin dose during hospitalization, demographic, echocardiographic, and angiographic data, medical history, drug treatment, and procedural characteristics. Continuous telemonitoring during the first 72 postoperative hours assessed for AF, which was defined as episodes lasting more than 5 minutes. The dose-related effect of atorvastatin on postoperative AF was investigated by logistic analysis in 1,607 patients: 75 (4.7%) did not receive atorvastatin vs 1,047 (65.1%) and 485 (30.2%) who received 40 mg/d or 80 mg/d, respectively, for at least 3 days before the operation. RESULTS: The study population was a mean age of 60.6 ± 9.5 years. Multivariate logistic regression demonstrated that a lack of atorvastatin pretreatment along with older age, enlarged left atrium, and male sex, and not taking ß-blockers, tended to be associated with an increased risk of postoperative AF. There was no significant difference between the effect of a higher (80 mg/d) and a lower dose (40 mg/d) in reducing postoperative AF. CONCLUSIONS: Atorvastatin pretreatment significantly reduced the occurrence of AF after bypass grafting; nonetheless, the difference between the beneficial effects of intensive and routine atorvastatin treatments on postoperative AF was not significant.

Anxiety-like behavior induced by histaminergic agents can be prevented by cannabinoidergic WIN55,212-2 injected into the dorsal hippocampus in mice.

In the present study, we investigate the effects of the histaminergic system and cannabinoid receptor agents on anxiety-related behaviors and their interactions using the hole-board test on mice. Bilateral intra-CA1 administration of the CB1/CB2 receptor agonist, WIN55, 212-2 (0.1-0.5microg/mouse) did not modify exploratory behaviors in mice. On the other hand, intra-CA1 administration of CB1 receptor antagonist, AM251 (25 and 50ng/mouse) or histamine, pyrilamine and ranitidine (5-10microg/mouse) decreased the amount of head-dipping and increased the first head-dip, suggesting an anxiogenic-like response. Furthermore, our present data indicated that the co-administration of WIN55, 212-2 (0.25microg/mouse) with histaminergic agents, decreased the anxiogenic-like response of an effective dose (5microg/mouse) of histamine and pyrilamine, but not that of ranitidine. In addition, the results demonstrated that co-administration of an ineffective dose of AM251 (15ng/mouse) with histaminergic drugs did not alter the response induced by an ineffective dose (3.75microg/mouse) of either histamine or pyrilamine and ranitidine. In all experiments and doses, locomotor activity and other exploratory behaviors were not significantly changed. In conclusion, our results showed that there is a chance of partial interaction between the cannabinoidergic and the histaminergic systems of the dorsal hippocampus on anxiogenic/anxiolytic-like behaviors in hole-board test.