Topical administration of a novel nitric oxide donor, linear polyethylenimine-nitric oxide/nucleophile adduct (DS1), selectively increases vaginal blood flow in anesthetized rats

The aim of the present study was to test the effects of a topical administration of a novel nitric oxide donor, linear polyethylenimine-nitric oxide/nucleophile adduct (DS1), on vaginal blood flow and hemodynamics in rats. Laser Doppler flowmetry was used to measure blood flow changes following topical application of DS1 (0.3 or 1.5 mg in 0.15 ml saline) into the vagina of anesthetized Wistar rats. In vivo hemodynamic parameters were measured with Millar-tip-catheter placed in the left ventricle. DS1 (1.5 mg) increased vaginal blood flow by 191+/-24, 226+/-22 and 166+/-23% of the baseline value (at 5, 15 and 30 min, respectively, after application) without affecting systemic blood pressure, heart rate and cardiac function. The increased vaginal blood flow following DS1 application returned to baseline between 45 and 60 min. Thus, topical application of nitric oxide donors such as DS1 may be useful for the treatment of female sexual dysfunction that develops due to an impairment of local blood flow supply to the vaginal tissue.

Anti-inflammatory effects of a novel, potent inhibitor of poly (ADP-ribose) polymerase

OBJECTIVE AND DESIGN

Oxygen- and nitrogen-derived free radicals and oxidants play an important role in the pathogenesis of various forms of inflammation. Recent work emphasizes the importance of oxidant-induced DNA strand breakage and activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) in the pathogenesis of various inflammatory diseases. We have recently demonstrated the efficacy of PJ34, a novel, potent phenanthridinone derivative PARP inhibitor, in rodent models of diabetic vascular dysfunction and stroke. Here we tested the efficacy of PARP inhibition in various models of local inflammation in rodents.

MATERIALS AND METHODS

PJ34 (at doses of 0.03-30 mg/kg) was tested in rats and mice subjected to standard models of inflammation, with relevant parameters of inflammation measured using standard methods.

RESULTS

PJ34 treatment (s.c, i.p. and i.v.) dose-dependently suppressed neutrophil infiltration and nitric oxide (but not KC and IL-1beta) production in peritonitis. In a model of systemic endotoxemia, PJ34 pretreatment significantly reduced plasma levels of TNF-alpha, IL-1beta and nitrite/nitrate (breakdown products of nitric oxide) production. PJ34 treatment (oral gavage) induced a significant suppression of the inflammatory response in dextran sulfate colitis, multiple low dose streptozotocin diabetes and cyclophosphamide-accelerated autoimmune diabetes in the non-obese diabetic mice, and reduced the degree of mononuclear cell infiltration into the iris in an endotoxin-induced uveitis model. Delaying the start of PJ34 administration in the colitis model conferred significant protective effects, while in the arthritis model the post-treatment paradigm lacked protective effects.

CONCLUSIONS

PJ34 provides significant, dose-dependent, anti-inflammatory effects in a variety of local inflammation models. Some of its actions are maintained in the post-treatment regimen and/or after discontinuation of treatment. We conclude that PARP inhibition offers a powerful means for reducing the severity of various forms of local inflammatory responses.

Protective effects of PJ34, a novel, potent inhibitor of poly(ADP-ribose) polymerase (PARP) in in vitro and in vivo models of stroke

Focal cerebral ischemia activates the nuclear protein poly(ADP-ribose) polymerase (PARP) by single DNA strand breaks which leads to energy depletion and cell necrosis. Deletion or inhibition of PARP protects against ischemic brain injury. Here we examined the neuroprotective effect of PJ34, a novel potent inhibitor of PARP in vitro and in vivo. Serum-free primary neuronal cultures derived from rat cortex (E15-17) and kept in culture for 10 days were exposed to oxygen glucose deprivation (OGD) in vitro. Neuronal injury was quantified by LDH release after 24 h. Pretreatment with 30-1000 nM PJ34 significantly protected from OGD-induced cell injury in a dose-dependent manner. For in vivo experiments SV/129 mice were treated with PJ34 (50 microg) by intraperitoneal injection 2 h before 1 h middle cerebral artery occlusion (MCAo) and again 6 h later. Twenty-three h after reperfusion ischemic injury was significantly decreased compared to vehicle-treated controls (infarct volume reduction of 40%, p<0.05). Similarly, in a rat model of MCAo (2 h occlusion followed by up to 22 h reperfusion), PJ34 administration (10 mg/kg i.v.) significantly reduced infarct size, and the effect of the drug was maintained even if it was given as late as 10 min prior to reperfusion time. PJ34 significantly protected in a 4 h, but not in a 24 h permanent occlusion model. In conclusion, PJ34, a novel, potent inhibitor of PARP exerts massive neuroprotective agents, with a significant therapeutic window of opportunity. The present work strengthens the concept that pharmacological PARP inhibition may be a suitable approach for the treatment of acute stroke in man.

Glutamine uptake at the blood-brain barrier is mediated by N-system transport

The mechanism of unidirectional transport of glutamine from blood to brain in pentobarbital-anesthetized rats was examined using in situ perfusion. Amino acid uptake into brain across the blood-brain barrier (BBB) is classically thought to be via the Na-independent large neutral (L-system), acidic and basic amino acid transporters. In the presence of physiological concentrations of amino acids in the perfusate, which should saturate the known amino acid transporters at the BBB, the cortical transfer constant (Ki) for L-[14C]glutamine was 11.6 +/- 1.1 microl/g/min. The addition of either 10 mM 2-amino-2-norbornanecarboxylic acid or 10 mM 2-amino-2-norbornanecarboxylic acid and 5 mM cysteine had no effect on the cortical Ki for L-[14C]glutamine, indicating that glutamine transport under these conditions does not occur by the L-, A-, or ASC-systems. Decreasing perfusate Na from 140 to 2.4 mM by Tris substitution reduced the cortical Ki for L-[14C]glutamine by 62% (p < or = 0.001). The Na-dependent uptake has the characteristics of N-system transport. It was inhibited by L-histidine and L-glutamine, both N-system substrates, and it was pH sensitive and moderately tolerant of Li substitution for Na. This putative N-system transporter at the luminal membrane of the BBB plays an important role in mediating brain glutamine uptake.