Involvement Of Nitric Oxide System Research Articles

Calcitonin Gene Related Peptide, Adrenomedullin, and Adrenomedullin 2 Function in Uterine Artery During Human Pregnancy.

Calcitonin gene-related peptide (CGRP) and its family members adrenomedullin (ADM) and adrenomedullin 2 (ADM2; also known as intermedin) support vascular adaptions in rat pregnancy. This study aimed to assess the relaxation response of uterine artery (UA) for CGRP, ADM, and ADM2 in nonpregnant and pregnant women and identify the involved mechanisms. (1) Segments of UA from nonpregnant women that were precontracted with U46619 (1μM) in vitro are insensitive to the hypotensive effects of CGRP, ADM, and ADM2; (2) CGRP, ADM, and ADM2 (0.1-100nM) dose dependently relax UA segments from pregnant women with efficacy for CGRP > ADM = ADM2; (3) the relaxation responses to CGRP, ADM, and ADM2 are differentially affected by the inhibitors of nitric oxide (NO) synthase (L-NAME), adenylyl cyclase (SQ22536), apamin, and charybdotoxin; (4) UA smooth muscle cells (UASMC) express mRNA for calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein (RAMP)1 and RAMP2 but not RAMP3; (5) receptor heterodimer comprising CRLR/RAMP1 and CRLR/RAMP2 but not CRLR/RAMP3 is present in UA; (6) soluble fms-like tyrosine kinase (sFLT-1) and TNF-α treatment decrease the expression of RAMP1 mRNA (P < 0.05) in UASMC; and (7) sFLT-1 treatment impairs the association of CRLR with all 3 peptides while TNF-α inhibits the interaction of CGRP but not ADM or ADM2 with CRLR in UASMC (P < 0.05). Relaxation sensitivity of UA for CGRP, ADM, and ADM2 is increased during pregnancy via peptide-specific involvement of NO system and endothelium-derived hyperpolarizing factors; vascular disruptors such as sFLT-1 and TNFα adversely impact their receptor system in UASMC.

Effect of acute lithium administration on penile erection: involvement of nitric oxide system

Lithium has been the treatment of choice for bipolar disorder (BD) for many years. Although erectile dysfunction is a known adverse effect of this drug, the mechanism of action by which lithium affects erectile function is still unknown. The aim was to investigate the possible involvement of nitric oxide (NO) in modulatory effect of lithium on penile erection (PE). We further evaluated the possible role of Sildenafil in treatment of lithium-induced erectile dysfunction. Erectile function was determined using rat model of apomorphine-induced erections. For evaluating the effect of lithium on penile erection, rats received intraperitoneal injection of graded doses of lithium chloride 30 mins before subcutaneous injection of apomorphine. To determine the possible role of NO pathway, sub-effective dose of N (G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, was administered 15 min before administration of sub-effective dose of lithium chloride. In other separate experimental groups, sub- effective dose of the nitric oxide precursor, L-arginine, or Sildenafil was injected into the animals 15 min before administration of a potent dose of lithium. 30 min after administration of lithium chloride, animals were assessed in apomorphine test. Serum lithium levels were measured 30 min after administration of effective dose of lithium. Lithium at 50 and 100 mg/kg significantly decreased number of PE (p<0.001), whereas at lower doses (5, 10 and 30 mg/kg) had no effect on apomorphine induced PE. The serum Li+ level of rats receiving 50 mg/kg lithium was 1±0.15 mmol/L which is in therapeutic range of lithium. The inhibitory effect of Lithium was blocked by administration of sub-effective dose of nitric oxide precursor L-arginine (100 mg/kg) (p<0.001) and sildenafil (3.5 mg/kg) (p<0.001) whereas pretreatment with a low and sub-effective dose of L-NAME (10mg/kg) potentiated sub-effective dose of lithium, (p<0.001). These results suggest acute treatments with lithium cause erectile dysfunction in an in-vivo rat model. Furthermore it seems that the NO pathway might play role in erectile dysfunction associated with lithium treatment. Findings also suggest that Sildenafil may be effective in treatment of lithium-associated erectile dysfunction.

Nitric oxide in central amygdala potentiates expression of conditioned withdrawal induced by morphine

Objective:The aim of this study was to evaluate if nitric oxide (NO) in the central amygdala (CeA) is involved in the expression of withdrawal aspects induced by morphine.Materials and Methods:Male Wistar rats (weighing 200-250 g) were bilaterally cannulated in the CeA and conditioned to morphine using an unbiased paradigm. Morphine (2.5-10 mg/kg) was subcutaneously injected once a day throughout the conditioning phase of the procedure. This phase also included 3-saline paired sessions. Naloxone (0.1-0.4 mg/kg, intraperitoneally [i.p.]), an antagonist of opioid receptors, was administered i.p. 10 min prior to testing of morphine-induced withdrawal features. The NO precursor, L-arginine (0.3-3 μg/rat) was intra-CeA injected prior to testing of naloxone response. To evaluate the involvement of NO system an inhibitor of NO synthase (NOS), NG-nitro-L-arginine methyl ester (L-NAME) (0.3-3 μg/rat), was injected ahead of L-arginine. Control group received saline solely instead of drug. As a complementary study, the activation of NOS was studied by nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d).Results:Morphine induced a significant increase in wet dog shaking and grooming behaviors compared with controls. Injection of naloxone pre-testing of morphine response significantly reversed the response to morphine. However, pre-microinjection of L-arginine intra-CeA recovered the response to morphine. Injection of L-NAME intra-CeA ahead of L-arginine though had no effect behaviorally, but, inhibited the NOS which has been evidenced by NADPH-d.Conclusion:The present study shows that NO in the CeA potentiates the expression of conditioned withdrawal induced by morphine paired with naloxone.

Chronic epigallocatechin-3-gallate ameliorates learning and memory deficits in diabetic rats via modulation of nitric oxide and oxidative stress

Due to anti-diabetic and antioxidant activity of green tea epigallocatechin gallate (EGCG) and the existence of evidence for its beneficial effect on cognition and memory, this research study was conducted to evaluate, for the first time, the efficacy of chronic EGCG on alleviation of learning and memory deficits in streptozotocin (STZ)-diabetic rats. Male Wistar rats were divided into control, diabetic, EGCG-treated-control and -diabetic groups. EGCG was administered at a dose of 20 and 40 mg/kg/day for 7 weeks. Learning and memory was evaluated using Y maze, passive avoidance, and radial 8-arm maze (RAM) tests. Oxidative stress markers and involvement of nitric oxide system were also evaluated. Alternation score of the diabetic rats in Y maze was lower than that of control and a significant impairment was observed in retention and recall in passive avoidance test ( p < 0.01) and EGCG treatment (40 mg/kg) of diabetic rats significantly improved these parameters ( p < 0.05). Also, diabetic animals exhibited fewer correct choices ( p < 0.01) and more errors ( p < 0.005) in the RAM task and EGCG (40 mg/kg) significantly ameliorated these changes ( p < 0.05). Further, pretreatment with l-arginine as a substrate for nitric oxide synthase (NOS) and/or 7-nitroindazole as a neuronal NOS inhibitor attenuated and potentiated the beneficial effect of EGCG regarding learning and memory respectively. Meanwhile, increased levels of malondialdehyde (MDA) and nitrite in diabetic rats significantly reduced due to EGCG treatment ( p < 0.05). In summary, chronic green tea EGCG dose-dependently could ameliorate learning and memory deficits in STZ-diabetic rats through attenuation of oxidative stress and modulation of NO.

Nitric oxide in the ventral tegmental area is involved in retrieval of inhibitory avoidance memory by nicotine

In the present study, the possible involvement of nitric oxide systems in the ventral tegmental area (VTA) in nicotine's effect on morphine-induced amnesia and morphine state-dependent memory in adult male Wistar rats was investigated. Step-through type inhibitory avoidance task was used to test memory retrieval. Post-training administration of morphine (5 and 7.5 mg/kg) induced amnesia. The response induced by post-training morphine was significantly reversed by pre-test administration of the drug. Pre-test injection of nicotine (0.4 and 0.8 mg/kg s.c.) alone and nicotine (0.1, 0.4 and 0.8 mg/kg s.c.) plus an ineffective dose of morphine also significantly reversed the amnesia induced by morphine. Morphine amnesia was also prevented by pre-test administration of l-arginine (1 and 3 μg/rat, intra-VTA), a nitric oxide (NO) precursor. Interestingly, an ineffective dose of nicotine (0.1 mg/kg s.c.) in combination with low dose of l-arginine (0.3 μg/rat, intra-VTA) synergistically improved memory performance impaired by morphine given after training. In contrast, pre-test administration of NG nitro-l-arginine methyl ester hydrochloride (l-NAME), a nitric oxide synthase (NOS) inhibitor (2 μg/rat, intra-VTA) prevented the nicotine reversal of morphine effect on memory. The results suggest a possible role for nitric oxide of ventral tegmental area in the improving effect of nicotine on the morphine-induced amnesia.

Nitric oxide system alteration at spinal cord as a result of perinatal asphyxia is involved in behavioral disabilities: Hypothermia as preventive treatment

Perinatal asphyxia (PA) is able to induce sequelae such as spinal spasticity. Previously, we demonstrated hypothermia as a neuroprotective treatment against cell degeneration triggered by increased nitric oxide (NO) release. Because spinal motoneurons are implicated in spasticity, our aim was to analyze the involvement of NO system at cervical and lumbar motoneurons after PA as well as the application of hypothermia as treatment. PA was performed by immersion of both uterine horns containing full-term fetuses in a water bath at 37 degrees C for 19 or 20 min (PA19 or PA20) or at 15 degrees C for 20 min (hypothermia during PA-HYP). Some randomly chosen PA20 rats were immediately exposed for 5 min over grain ice (hypothermia after PA-HPA). Full-term vaginally delivered rats were used as control (CTL). We analyzed NO synthase (NOS) activity, expression and localization by nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) reactivity, inducible and neuronal NOS (iNOS and nNOS) by immunohistochemistry, and protein nitrotyrosilation state. We observed an increased NOS activity at cervical spinal cord of 60-day-old PA20 rats, with increased NADPH-d, iNOS, and nitrotyrosine expression in cervical motoneurons and increased NADPH-d in neurons of layer X. Lumbar neurons were not altered. Hypothermia was able to maintain CTL values. Also, we observed decreased forelimb motor potency in the PA20 group, which could be attributed to changes at cervical motoneurons. This study shows that PA can induce spasticity produced by alterations in the NO system of the cervical spinal cord. Moreover, this situation can be prevented by perinatal hypothermia.

Escitalopram increases cortical nitric oxide synthase (NOS) in rat brain during ethanol withdrawal

The effect of escitalopram on ethanol withdrawal syndrome (EWS) and involvement of nitric oxide system in rats was investigated. Male Wistar rats divided into five experimental groups of eight animals each: (a) control group; (b) EWS (saline) group; (c) escitalopram 2.5 mg group; (d) escitalopram 5 mg group and (e) escitalopram 10 mg group. Ethanol dependence was induced in rats by ethanol-containing liquid diet and ethanol withdrawal was precipitated by replacing ethanol free diet. Ethanol receiving rats in individual groups were decapitated on 21st day of ethanol ingestion and at sixth hour of ethanol withdrawal. Brains were removed and dissected. Five regions of the brain were dissected: the frontal cortex, cerebellum, striatum, hippocampus and hypothalamus. Immunohistochemical NOS staining was performed. The NOS staining intensity in cortex and hypothalamus regions were significantly lower in EWS group than control group. During EWS period, in rats given 2.5 and 10 mg/kg escitalopram, the staining intensity in cortex, striatum and hippocampus were found to be 11.492, 8.519 and 11.234, respectively, and was statistically different than the control group. The hippocampal NOS staining intensity was found to be significantly decreased with 2.5 mg/kg escitalopram, whereas the cortex, striatum and hippocampal staining intensity were increased significantly with 5 mg/kg. In 10 mg/kg escitalopram group, staining properties were not different than those of the control group. Our results suggest that NOS decreases during ethanol withdrawal in cortex and hypothalamus of rat brain and treatment with escitalopram reverses the enzyme density in cortex but not hypothalamus.

Involvement of nitric oxide system in enhancement of morphine-induced conditioned place preference by agmatine in male mice

Agmatine recently has been suggested as a neurotransmitter, is able to interact with various effects of morphine like analgesia and dependence. In this study, the effects of agmatine on rewarding properties of morphine, and the possible involvement of nitric oxide (NO) system has been evaluated in an unbiased conditioned place preference (CPP) paradigm. Agmatine (1, 5 and 10 mg/kg, i.p.) alone induced neither CPP nor conditioned place aversion (CPA). Morphine (0.01, 0.05, 0.1 and 0.5 mg/kg, s.c.), while unable to show CPP or CPA, induced CPP in mice pretreated with agmatine. L-arginine (200 mg/kg, i.p.), a NO precursor, significantly enhanced the effect of agmatine (5 mg/kg) on morphine (0.5 mg/kg)-induced place preference. N G-nitro- l-arginine methyl ester ( l-NAME; 2.5 mg/kg, i.p.), a non specific nitric oxide synthase (NOS) inhibitor, and aminoguanidine (50 and 100 mg/kg, i.p.), a specific inducible NOS inhibitor, significantly reduced the effect of agmatine (5 mg/kg) on morphine (0.5 mg/kg)-induced place preference. These results suggest the possible involvement of inducible nitric oxide system in potentiating effects of agmatine on morphine-induced place preference.

Involvement of nitric oxide system in experimental muscle crush injury.

Muscle crush injury is often complicated by hemodynamic shock, electrolyte disorders, and myoglobinuric renal failure. In this study, we examined the involvement of the nitric oxide (NO) system in the development of muscle damage in an experimental model of crush injury induced by exertion of standardized mechanical pressure on tibialis muscle of rat. The intact limb served as a control. Four days after injury, the crushed muscle was characterized by extreme capillary vasodilatation as demonstrated by histological morphometric analysis. These changes were accompanied by muscle hyperperfusion as evaluated by measurements of femoral blood flow (ultrasonic flowmetry) and capillary blood flow (laser-doppler flowmetry). Treatment with Nomega-nitro-L-arginine methyl ester, a NO synthase (NOS) inhibitor, largely decreased the hyperperfusion. Furthermore, the expression of the different NOS isoforms, assessed by reverse transcription-PCR and immunoreactive levels, determined by Western blot, revealed a remarkable induction of the inducible NOS in the crushed limb. Similarly, endothelial NOS mRNA increased gradually after the induction of muscle damage. In contrast, the major muscular NOS, i.e., neuronal isoform remained unchanged. In line with the alterations in the mRNA levels, Western blot analysis revealed parallel changes in the immunoreactive levels of the various NOS. These findings indicate that muscle crush is associated with activation of the NO system mainly due to enhancement of iNOS. This may contribute to NO-dependent extreme vasodilatation in the injured muscle and aggravate the hypovolemic shock after crush injury.