Involvement of adenosine triphosphate-sensitive potassium channels in the neuroprotective activity of hydrogen sulfide in the 6-hydroxydopamine-induced animal model of Parkinson's disease.

Studies have shown that hydrogen sulfide (H2S) exerts a neuroprotective effect and may have a therapeutic value for treating neurodegenerative diseases including Parkinson's disease. However, little is known about the mechanisms underlying the neuroprotective activity of H2S in vivo. Here, we evaluated the effect of glibenclamide, an ATP-sensitive potassium channel blocker, on the neuroprotective activity of H2S in the 6-hydroxydopamine (6-OHDA) animal model of Parkinson's disease. 6-OHDA was administered by stereotaxic surgery into the medial forebrain bundle. Sodium hydrosulfate (NaHS, 3 and 5.6 mg/kg), as a donor of H2S, alone or in combination with glibenclamide (5 mg/kg), was daily injected for 7 days starting 1-2 h before the stereotaxic surgery. After an apomorphine-induced rotational test, the number of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta was determined by immunofluorescence. The striatal dopamine level and oxidative stress markers were also measured in brain homogenates. Pretreatment with NaHS significantly attenuated 6-OHDA-induced motor asymmetry in the rotational test. Histological and biochemical evaluations demonstrated that NaHS, especially at high dose, increased the survival of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta and reduced the decreasing effect of 6-OHDA on striatal dopamine levels. However, co-administration of glibenclamide reversed the antiparkinsonian and neuroprotective effects of NaHS. However, glibenclamide did not change the reducing effect of NaHS on 6-OHDA-induced overproduction of malondialdehyde. Our data show that ATP-sensitive potassium channels are involved in the antiparkinsonian and neuroprotective effects of H2S in the 6-OHDA animal model of Parkinson's disease.

Dopaminergic Neuronal Death in Substantia Nigra Associates with Serum Levels of Total Bilirubin, Selenium, and Zinc: Evidences from 6-Hydroxydopamine Animal Model of Parkinson's Disease.

Mild to moderate dopaminergic (DA) neuronal death in substantia nigra pars compacta (SNc) as the main pathological hallmark of Parkinson's disease (PD) is usually silent and does not produce marked clinical symptoms. In this study, we investigated the association between SNc DA neuronal loss and serum levels of total bilirubin (TB), selenium (Se), and zinc (Zn) in 6-hydroxydopamine (6-OHDA) animal model of PD. The neurotoxin of 6-OHDA was injected into the medial forebrain bundle of right hemisphere by stereotaxic surgery. Two conventional behavioral tests were carried out in several steps after the toxin to confirm the model reproduction and quantify severity and progress of 6-OHDA-induced PD. Blood samples were collected within 1 week before the toxin and in the second, fifth, and eighth weeks thereafter. Immunohistochemistry (IHC) assessments were performed on the rat's brain to determine the severity of DA neuronal loss in SNc. The severity of behavioral symptoms and TB levels were progressively increased in 6-OHDA-treated rats. On the other hand, Se and Zn levels in them were lower than control. These changes were observed in rats with severe or mild behavioral symptoms. Also, IHC revealed that changes in TB, Se, and Zn associate with SNc DA neuronal loss but do not correlate with its severity. Significant changes in serum levels of TB, Se, and Zn in the mild SNc DA neuronal loss suggest them as valuable parameters for establishment of a serum profile for early detection of PD.

Evaluation of the Association Between Serum Levels of Testosterone and Prolactin With 6- Hydroxydopamine-Induced Parkinsonism in Male Rats.

INTRODUCTION: Parkinson's Disease (PD) associates with changes in sex hormones; however, it remains unknown whether this is either a cause for or a result of the disease. To further evaluate it, we investigated if the development of 6-Hydroxydopamine (6-OHDA)-induced Parkinsonism changes the serum levels of testosterone and prolactin or not. METHODS: 6-OHDA was injected into the medial forebrain bundle using stereotaxic surgery. The development of Parkinsonism was evaluated by apomorphine-induced rotational test and the immunofluorescence labeling of Dopaminergic (DA) neurons in substantia nigra. The necessary blood samples were collected before the toxin and in the third and sixth weeks afterward. The hormones levels were determined using Enzyme-Linked Immunosorbent Assay (ELISA) kits. RESULTS: The severity of rotations was different among 6-OHDA-treated rats; accordingly, they were divided into two subgroups of severe and mild parkinsonian rats. The degeneration of DA neurons was observed in both subgroups; however, it was significantly less in the mild group. In the sixth week after the toxin, testosterone level increased but only in the severe subgroup. Prolactin increased in both subgroups in the third week after the toxin but returned to normal in the sixth week. There was no association between the pre-toxin levels of these hormones and the intensity of Parkinsonism. CONCLUSION: Our findings indicated that the development of 6-OHDA-induced Parkinsonism increases the serum levels of testosterone and prolactin. Increased prolactin occurred earlier and was observed in rats with less DA neuronal loss. Therefore, prolactin levels can predict the death of DA neurons before the clinical signs of PD were revealed.

Safety and efficacy of Favipiravir in moderate to severe SARS-CoV-2 pneumonia.

BACKGROUND: We examined the safety and efficacy of a treatment protocol containing Favipiravir for the treatment of SARS-CoV-2. METHODS: We did a multicenter randomized open-labeled clinical trial on moderate to severe cases infections of SARS-CoV-2. Patients with typical ground glass appearance on chest computerized tomography scan (CT scan) and oxygen saturation (SpO2) of less than 93% were enrolled. They were randomly allocated into Favipiravir (1.6 gr loading, 1.8 gr daily) and Lopinavir/Ritonavir (800/200 mg daily) treatment regimens in addition to standard care. In-hospital mortality, ICU admission, intubation, time to clinical recovery, changes in daily SpO2 after 5 min discontinuation of supplemental oxygen, and length of hospital stay were quantified and compared in the two groups. RESULTS: 380 patients were randomly allocated into Favipiravir (193) and Lopinavir/Ritonavir (187) groups in 13 centers. The number of deaths, intubations, and ICU admissions were not significantly different (26, 27, 31 and 21, 17, 25 respectively). Mean hospital stay was also not different (7.9 days [SD = 6] in the Favipiravir and 8.1 [SD = 6.5] days in Lopinavir/Ritonavir groups) (p = 0.61). Time to clinical recovery in the Favipiravir group was similar to Lopinavir/Ritonavir group (HR = 0.94, 95% CI 0.75 - 1.17) and likewise the changes in the daily SpO2 after discontinuation of supplemental oxygen (p = 0.46) CONCLUSION: Adding Favipiravir to the treatment protocol did not reduce the number of ICU admissions or intubations or In-hospital mortality compared to Lopinavir/Ritonavir regimen. It also did not shorten time to clinical recovery and length of hospital stay.

Evaluation of the antiparkinsonism and neuroprotective effects of hydrogen sulfide in acute 6-hydroxydopamine-induced animal model of Parkinson's disease: behavioral, histological and biochemical studies.

INTRODUCTION: Studies have shown that hydrogen sulfide (H2S), a gaseous neurotransmitter, has neuroprotective effect. Here, we evaluated the neuroprotective activity of H2S in acute 6-hydroxydopamine (6-OHDA) animal model of Parkinson's disease (PD). METHODS: 6-OHDA was injected through stereotaxic surgery into medial forebrain bundle (MFB) of the right hemisphere to induce severe and fast degeneration in dopaminergic neurons of substantia nigra (SN). NaHS, as donor of H2S, was daily injected at doses of 3 and 5.6 mg/kg for seven days starting a few hours before the surgery. A series of behavioral tests were carried out and then, remaining tyrosine hydroxylase (TH)-positive neurons in substantia nigra pars compacta (SNc) was determined using immunohistfluresance staining. Striatal dopamine level and oxidative stress markers were also measured in the brain homogenates using immunosorbent assay kits. RESULTS: NaHS attenuated apomorphine-induced rotational activity, decreased bias swings in elevated body swing test and increased falling time in rotarod test. Our histological and biochemical data demonstrated that NaHS treatment increases the survival of TH-positive neurons in SNc and also reduces the decreasing effect of 6-OHDA on striatal dopamine level. NaHS also reduced 6-OHDA-induced malondialdehyde overproduction but had no effect on the superoxide dismutase and glutathione peroxidase activity. CONCLUSION: Our results show that H2S produces significant antiparkinsonism and neuroprotective effects against 6-OHDA neurotoxicity. Since injection of 6-OHDA into MFB produces severe lesion in SN dopaminergic neurons similar to this lesion in the onset of PD in human being, our data recommend H2S as potential therapeutic target for treatment of this disease.