Alexandre Mazzanti

Pre-treatment with ebselen and vitamin E modulate acetylcholinesterase activity: interaction with demyelinating agents

The ethidium bromide (EB) demyelinating model was associated with vitamin E (Vit E) and ebselen (Ebs) treatment to evaluate acetylcholinesterase (AChE) activity in the striatum (ST), hippocampus (HP), cerebral cortex (CC) and erythrocytes. Rats were divided into seven groups: I—Control (saline), II—(canola); III—(Ebs), IV—(Vit E); V—(EB); VI—(EB + Ebs) and VII—(EB + Vit E). At 3 days after the EB injection, AChE activity in the CC and HC was significantly reduced in groups III, IV, V, VI and VII (p < 0.05) and in the ST it was reduced in groups III and V (p < 0.05) when compared to the control group. At 21 days after the EB injection, AChE activity in the CC was significantly reduced in groups III, IV and V, while in groups VI and VII a significant increase was observed when compared to the control group. In the HC and ST, AChE activity was significantly reduced in groups V, VI and VII when compared to the control group (p < 0.05). In the erythrocytes, at 3 days after the EB injection, AChE activity was significantly reduced in groups III, IV, V, VI and VII and at 21 days there was a significant reduction only in groups VI and VII (p < 0.05) when compared to the control group. In conclusion, this study demonstrated that Ebs and Vit E interfere with the cholinergic neurotransmission by altering AChE activity in the different brain regions and in the erythrocytes. Furthermore, treatment with Vit E and Ebs protected against the demyelination lesion caused by EB. In this context, we can suggest that ebselen and Vit E should be considered potential therapeutics and scientific tools to be investigated in brain disorders associated with demyelinating events.

Activity of ectonucleotidases and adenosine deaminase in rats exposed to cigarette smoke

Cigarette smoke is a complex mixture of various toxic substances that are capable of initiating oxidative damage and promoting blood platelet alterations. In this study, we investigated the activities of the ectoenzymes NTPDase (ectonucleoside triphosphate diphosphohydrolase, CD39) and 5′-nucleotidase (CD73) in platelets as well as adenosine deaminase (ADA) in the plasma of rats exposed to aged and diluted sidestream smoke during 4 weeks. The rats were divided into two groups: I (control) and II (exposed to smoke). After the exposure period, blood was collected and the platelets and plasma were separated for enzymatic assay. The results demonstrated that NTPDase (with ATP as substrate) and 5′-nucleotidase (AMP as substrate) activities were significantly higher in group II (p < 0.05) as compared to group I, while no significant difference was observed for NTPDase with ADP as substrate. The ADA activity was significantly reduced in group II (p < 0.05) as compared with group I. Platelet aggregation was significantly increased in group II (p < 0.05) as compared with group I. We suggest that these alterations in the activity of enzymes from the purinergic system are associated with an increase in platelet aggregation. However, our study has demonstrated that the organism tries to compensate for this enhanced aggregation by increasing hydrolysis of AMP and reducing hydrolysis of adenosine, a potent inhibitor of aggregation and an important modulator of vascular tone.

Vitamin E Decreased the Activity of Acetylcholinesterase and Level of Lipid Peroxidation in Brain of Rats Exposed to Aged and Diluted Sidestream Smoke

INTRODUCTION The biological systems of both smoker and passive smoking suffer changes caused by toxic compounds from cigarette smoke such as inflammation, lipid peroxidation, and deficiency of vitamin E. The aim of the present study was to evaluate the effect of vitamin E on acetylcholinesterase (AChE) activity and the lipid peroxidation level in the brain of rats in the model of exposure to aged and diluted sidestream smoke (ADSS). METHODS Adult male Wistar rats (200-300 g) were exposed to ADSS for 4 weeks and treated with vitamin E (50 mg/kg/day) loaded by gavage. In the first, second, third, and fourth weeks, animals were concomitantly exposed to the smoke of 1, 2, 3, and 4 cigarettes/day, respectively. The duration of each exposure was 15 min, daily. RESULTS For rats exposed to ADSS, the AChE activity and lipid peroxidation level increased in the striatum, cerebral cortex, and cerebellum. In contrast, the activity of AChE and the level of lipid peroxidation decreased in the smoke group treated with vitamin E. CONCLUSIONS The results suggest that the rats exposed to ADSS and treated with vitamin E significantly reduced the raised activity of AChE and level lipid peroxidation from the brain structures studied. The study, therefore, concludes that vitamin E could be considered as a therapeutic agent in this type of exposure.

17-β estradiol in the acetylcholinesterase activity and lipid peroxidation in the brain and blood of ovariectomized adult and middle-aged rats

AIMS To investigate the 17-β estradiol in the acetylcholinesterase activity and lipid peroxidation in the brain and blood of ovariectomized rats of different ages. MAIN METHODS Animals were randomly assigned into three experimental groups of each age (n=6). Control groups consisted of adult (sham-A) and middle-aged (sham-MA) female rats, ovariectomized adult (OVX-A) and middle-aged (OVX-MA) rats without estrogen therapy reposition, and ovariectomized adult (OVX+E2-A) and middle-aged (OVX+E2-MA) rats treated with 17-β estradiol for 30days. After this period, AChE activity and lipid peroxidation were measured in the brain and blood. KEY FINDINGS The AChE activity increased (p<0.05) in striatum (ST) in OVX-A, OVX+E2-A and OVX-MA, and hippocampus (HP) in OVX-MA. The enzyme activity decreased (p<0.05) in ST of OVX+E2-MA, and cerebral cortex (CC) in OVX+E2-A, OVX-MA and OVX+E2-MA. Blood AChE activity increased (p<0.05) in OVX+E2-A and decreased (p<0.05) in OVX-MA. Lymphocyte AChE activity increased (p<0.05) in OVX-A and OVX+E2-A and decreased (p<0.05) in OVX-MA. Lipid peroxidation increased (p<0.05) in ST of OVX-A, CC of OVX-A and OVX-MA, HP of OVX-A, and cerebellum (CE) of OVX-A, OVX-MA, and OVX+E2-MA. Lipid peroxidation decreased (p<0.05) in ST, CC and CE of OVX+E2-A, and ST and HP of OVX+E2-MA. Similar values of lipid peroxidation to control groups were found in ST and HP of OVX-MA, HP of OVX+E2-A and CC of OVX+E2-MA. SIGNIFICANCE 17-β estradiol is able to modulate the AChE activity and non-neuronal cholinergic response as well as to reduce lipid peroxidation. Its response is dependent on the age and brain structure analyzed.

O Herpesvírus bovino tipo 5 (BoHV-5) pode utilizar as rotas olfatória ou trigeminal para invadir o sistema nervoso central de coelhos, dependendo da via de inoculação

Bovine herpesvirus type 5 (BoHV-5) is a major etiological agent of meningoencephalitis in cattle. Following replication in the nasal mucosa, viral invasion of the brain is thought to occur mainly by the olfactory pathway. To address the role of this pathway in the pathogenesis of neurological infection in a laboratory model, 30 days old rabbits had the main olfactory bulbs (MOBs) surgically removed and were subsequently inoculated intranasally (IN) or conjunctivally (IC) with a highly neurovirulent BoHV-5 strain (SV-507). Following IN inoculation, 10 out of 10 (100 %) control rabbits developed neurological disease. The clinical onset ranged from day 5 to 10 post-inoculation (pi, average 7.5 days); nine being euthanized in extremis and one recovering after a mild clinical course. In contrast, only one rabbit (9.1 %) of the group lacking the MOBs (n=11) developed neurological disease (onset at day 17 pi). Dexamethasone administration to the survivors (n=10) at day 50pi was followed by virus shedding in nasal and/or ocular secretions by 8 animals, demonstrating that the virus was able to reach the trigeminal ganglia (TG) during acute infection. These results demonstrate that the olfactory route provides the main, yet not the sole access to the brain of rabbits following IN inoculation. To address the role of a second pathway, groups of control (n=12) or MOB-lacking rabbits (n=12) were inoculated into the conjunctival sac (IC), following which the virus would be expected to use the ophtalmic branch of the trigeminal nerve to reach the brain. Ten control rabbits (83.3 %) developed neurological disease upon IC inoculation (onset 15.3 days 11 to 20). Previous ablation of the MOBs did not affect the frequency and course of neurological disease: ten out of 12 rabbits (83.3 %) lacking the MOBs developed neurological disease (onset 9 to 15 dpi, average: 12.7 days) upon IC inoculation. These results demonstrate that both IN and IC routes may operate in the transport of BoHV-5 to the brain of experimentally infected rabbits, depending on the route of inoculation. IN inoculation results in a fast and efficient transport by the olfactory pathway, the trigeminal route providing an alternative, much slower and less efficient transport; IC inoculation results in efficient viral transport by the trigeminal route, yet with a delayed kinetics comparing to the transport provided by the olfactory pathway.

Effects of diphenyl diselenide on lipid profile and hepatic oxidative stress parameters in ovariectomized female rats

Objectives  Ovarian hormone decline after menopause is linked to many pathophysiological reactions. Female rats submitted to ovariectomy are employed as a model of post‐menopausal condition. This study investigated the effects of diphenyl diselenide (PhSe)2 on body weight gain, intra‐abdominal fat deposition, plasma lipid profile and hepatic oxidative stress in ovariectomized rats.

Neuroprotective role of quercetin in locomotor activities and cholinergic neurotransmission in rats experimentally demyelinated with ethidium bromide

AIM The purpose of this study was to investigate whether the flavonoid quercetin can prevent alterations in the behavioral tests and of cholinergic neurotransmission in rats submitted to the ethidium bromide (EB) experimental demyelination model during events of demyelination and remyelination. MAIN METHODS Wistar rats were randomly distributed into four groups (20 animals per group): Control (pontine saline injection and treatment with ethanol), Querc (pontine saline injection and treatment with quercetin), EB (pontine 0.1% EB injection and treatment with ethanol), and EB+Querc (pontine 0.1% EB injection and treatment with quercetin). The groups Querc and Querc+EB were treated once daily with quercetin (50mg/kg) diluted in 25% ethanol solution (1ml/kg) and the animals of the control and EB groups were treated once daily with 25% ethanol solution (1ml/kg). Two stages were observed: phase of demyelination (peak on day 7) and phase of remyelination (peak on day 21 post-injection). Behavioral tests (beam walking, foot fault and inclined plane test), acetylcholinesterase (AChE) activity and lipid peroxidation in pons, cerebellum, hippocampus, hypothalamus, striatum and cerebral cortex were measured. KEY FINDINGS The quercetin promoted earlier locomotor recovery, suggesting that there was demyelination prevention or further remyelination velocity as well as it was able to prevent the inhibition of AChE activity and the increase of lipidic peroxidation, suggesting that this compound can protect cholinergic neurotransmission. SIGNIFICANCE These results may contribute to a better understanding of the neuroprotective role of quercetin and the importance of an antioxidant diet in humans to provide benefits in neurodegenerative diseases such as MS.

Homoimplante ortotópico conservado, associado à terapia "soft laser" na reparação tenopatelar em cão

The aim of the present research was to develop an alternative method of treatment for tenopatellar lesions. The tenopatellar implant, preserved in glycerin 98%, was applied in 24 dogs, associated (group I - twelve dogs) or not (group II - twelve dogs) to laser therapy with gallium arsenide during the first ten post-operative days. The animals in each group were divided again in subgroups according to body weight (between 10 and 20kg or between 21 and 30kg) and according to post-operative period (60, 120 and 180 days) of evaluation. The stifle joint was immobilized through percutaneous external skeletal fixation type II for 30 post-operative days. Temporary articular immobilization provided adequate joint stability. At radiographic exams, different stages of bone resorption from the implant were verified, being more evident at 180 days post-operativelly. Microscopically, fragments of osteal trabecules of the graft, in reabsorption phase, surrounded by osteoclasts and filled with fibrovascular tissue were verified in all the groups. Newbone formation at the graft from endochondral ossification, more evident at the 180th day group, was noted. Despite the need for more studies, with a longer period of post-operatory evaluation, the implant of an orthotopic homologous tenopatellar segment preserved in glycerin 98% is suitable for replacement of tenopatellar segments in dogs weighting up to 30 kg.

Analgesia epidural com clonidina ou romifidina em cães submetidos à cirurgia coxofemoral

Cardiovascular alterations and analgesia in 14 dogs submitted to epidural administration of clonidine or romifidine to enable coxofemoral surgery were evaluated. Dogs were separated in two groups: Cloni group received 150µg of clonidine and Romi group, 20µg/kg of romifidine. Anesthetic induction was performed using propofol (8mg/kg) and maintenance using halothane and O2 in spontaneous breathing. The puncture of epidural space was performed just after anesthetic induction. Heart rate and respiratory rate, systolic arterial rate, hemoglobin oxygen saturation and halothane concentration were assessed before anesthetic induction, and at each 10 minutes until the end of the surgery. Samples of arterial blood were collected after anesthesic induction and at the end of the surgical procedure in order to assess pH, PaCO2, PaO2, SaO2, BE and HCO3- levels. The analgesia degree (intense, middle or inadequated) was evaluated for two postoperative hours. Numerical data were analysed with ANOVA and Bonferronis test (P< 0.05). Dogs of Romi group had bradycardia, bradyarrhrytmia, and hypertension. The heart rate and systolic arterial pressure in the Cloni group were within the physiologic variation parameter to dogs. In conclusion epidural administration of clonidine or romifidine produce intense intraoperative analgesia, with no respiratory depression, and middle analgesia for two postoperative hours. Bradycardia and hypotension were not observed with epidural clonidine, however, bradyarrhytmia and hypertension ocurred with epidural romifidine.

Diphenyl diselenide ameliorates cognitive deficits induced by a model of menopause in rats.

Ovarian hormone loss contributes to cognitive decline in postmenopausal women. Studies have demonstrated a positive role of the level of the element selenium in cognitive performance. The present study investigated the effects of the synthetic organoselenium compound diphenyl diselenide (PhSe)2 on cognitive functions in ovariectomized rats. Ninety-day-old female Wistar rats were subjected to ovariectomy (OVX) or Sham operation. One week after surgery, rats were orally treated with (PhSe)2 (5 mg/kg, per oral route) or vehicle once a day for 30 days. Next, the rats were evaluated in behavioral tests [Morris water maze (MWM) and open-field tests] and biochemical [cerebral acetylcholinesterase (AChE)] analyses were carried out. In MWM probe trial, (PhSe)2 decreased the latency to reach the platform location and increased the number of crossings over the platform location, protecting against cognitive impairment induced by OVX. Furthermore, (PhSe)2 prevented the stimulation of AChE activity caused by OVX. In conclusion, the present study showed a cognition-enhancing effect of (PhSe)2 treatment for 30 days in ovariectomized rats in the MWM test, which could be related to its ability to prevent the stimulation of AChE activity caused by OVX in rats. These findings suggest that (PhSe)2 might have a promising role in preventing the cognitive decline related to menopause.