Central release of nitric oxide mediates antinociception induced by aerobic exercise

Nitric oxide (NO) is a soluble gas that participates in important functions of the central nervous system, such as cognitive function, maintenance of synaptic plasticity for the control of sleep, appetite, body temperature, neurosecretion, and antinociception. Furthermore, during exercise large amounts of NO are released that contribute to maintaining body homeostasis. Besides NO production, physical exercise has been shown to induce antinociception. Thus, the present study aimed to investigate the central involvement of NO in exercise-induced antinociception. In both mechanical and thermal nociceptive tests, central [intrathecal (it) and intracerebroventricular (icv)] pretreatment with inhibitors of the NO/cGMP/KATP pathway (L-NOArg, ODQ, and glybenclamide) prevented the antinociceptive effect induced by aerobic exercise (AE). Furthermore, pretreatment (it, icv) with specific NO synthase inhibitors (L-NIO, aminoguanidine, and L-NPA) also prevented this effect. Supporting the hypothesis of the central involvement of NO in exercise-induced antinociception, nitrite levels in the cerebrospinal fluid increased immediately after AE. Therefore, the present study suggests that, during exercise, the NO released centrally induced antinociception.

Effect of cervical sympathetic block on cerebral vasospasm after subarachnoid hemorrhage in rabbits

PURPOSE: Cerebral vasospasm (CVS) is a major complication after subarachnoid hemorrhage (SAH) induced by the rupture of intracranial aneurysms. The aim of the present study was to investigate the effect and mechanism of cervical sympathetic block on cerebral vasospasm of the rabbits after SAH. METHODS: After successful modeling of cervical sympathetic block, 18 healthy male white rabbits were randomly divided into three groups (n=6), ie, sham operation group (Group A), SAH group (Group B) and SAH with cervical sympathetic block group (Group C). Models of delayed CVS were established by puncturing cisterna magna twice with an injection of autologous arterial blood in Groups B and C. A sham injection of blood through cisterna magna was made in Group A. 0.5 ml saline was injected each time through a catheter for cervical sympathetic block after the first injection of blood three times a day for 3 d in Group B (bilateral alternating). 0.5 ml of 0.25% bupivacaine was injected each time through a catheter for cervical sympathetic block after the first injection of blood three times a day for 7 d in Group B. 2 ml venous blood and cerebrospinal fluid were obtained before (T1), 30 min (T2) and 7 d (T3) after the first injection of blood, respectively, and conserved in a low temperature refrigerator. Basilar artery value at T1, T2 and T3 was measured via cerebral angiography. The degree of damage to nervous system at T1 and T3 was recorded. RESULTS: There was no significant difference in diameter of basilar artery at T1 among three groups. The diameters of basilar artery at T2 and T3 of Groups B and C were all smaller than that in Group A, which was smaller than Group C, with a significant difference. There was no significant difference in NO and NOS in plasma and cerebrospinal fluid among three groups. The NO and NOS contents at T2 and T3 of Groups B and C were all lower than Group A; Group C was higher than Group B, with a significant difference. The nerve function at T3 of Groups B and C were all lower than Group A and that of Group C higher than Group B, with a significant difference. CONCLUSION: Cervical sympathetic block can relieve cerebral vasospasm after subarachnoid hemorrhage and increase NO content and NOS activity in plasma and cerebrospinal fluid to promote neural functional recovery.

Recent advances in the pathophysiology of meningitis in children

Over the past decade, much has changed on the landscape of meningitis. The purpose of this study was to investigate the involvement of nitric oxide [NO] and tumor necrosis factor alpha [TNF-alpha] in the pathogenesis of childhood meningitis. We measured the concentration of NO[-][2] [a stable metabolite of NO] and TNF-alpha in serial samples of cerebrospinal fluid [CSF] from 21 children with septic and 18 with aseptic meningitis and 20 control patients without meningitis. Significantly higher CSF NO[2] concentrations were detected in those with bacterial meningitis than those with aseptic meningitis [27.6 +/- 26.8 versus 12.2 +/- 12.3 micro mol/L; P<0.001] or among non-meningitis subjects [13.2 +/- 24.2 micro mol/L; P<0.0001]. Clinical and laboratory improvement following administration of antibiotics and dexamethasone was associated with a fall in CSF [NO[-][2] to normal levels in these patients. The mean [ +/- SD] of concentration in septic meningitis was 148.74 +/- 338.77 pg/ml. There was significantly more TNF-alpha than aseptic meningitis [6.85 +/- 17.93 pg/ml; [P<0.,001] or non-meningitis [7.67 +/- 16.07 pg/ml; P<0.001]. We did not find a correlation between CSF nitrate/nitrite levels and TNF-alpha [r = 0.046]. Our findings indicate that NO and TNF- alpha [r = 0.046]. Our findings indicate that NO and TNF- alpha [r = 0.046]. Our findings indicate that NO and TNF- alpha production are enhanced in the CSF compartment of children with septic meningitis and support the hypothesis that both markers are involved in the pathophysiology of septic meningitis

CSF cytokines, nitric oxide and prostaglandins in diagnosis and pathophysiology of childhood CNS leukemia and lymphoma

To clarify the role of cytokines, nitric oxide [NO] and prostaglandin- E2 [PG-E2] in diagnosis and pathogenesis of infiltration of central nervous system [CNS] in cases with leukemia and lymphoma, the levels of these indices in the cerebrospinal fluid [CSF] of those children were determined. Their levels were correlated with other laboratory studies of CSF and clinical criteria. This study included twenty- seven children with acute leukemia [twenty with acute lymphoblastic leukemia [ALL] and seven with acute myeloid leukemia [AML]] and fifteen with non- Hodgkin's lymphoma [NHL]. Clinical evidence of CNS involvement was present in seventeen patients with acute leukemia and seven cases with NHL. The study revealed significantly elevated levels of two types of cytokines [TNF-alpha, IL-6] NO and PG-E2 in CSF of children with acute leukemias and lymphoma compared with control group [children with tension headache or meningism]