Stephen A. Adefegha

Berberine protects against memory impairment and anxiogenic-like behavior in rats submitted to sporadic Alzheimer’s-like dementia: Involvement of acetylcholinesterase and cell death

The present study aimed to investigate the effects of berberine (BRB) on spatial and learning memory, anxiety, acetylcholinesterase activity and cell death in an experimental model of intracerebroventricular streptozotocin (ICV-STZ) induced sporadic Alzheimers-like dementia. Sixty male Wistar rats were randomly divided into six groups: control (CTR), BRB 50mg/kg (BRB 50), BRB 100mg/kg (BRB 100), streptozotocin (STZ), streptozotocin plus BRB 50mg/kg (STZ+BRB 50), and streptozotocin plus BRB 100mg/kg (STZ+BRB 100). Rats were injected with ICV-STZ (3mg/kg) or saline, and daily oral BRB treatment began on day 4 for a period of 21days. Behavioral tests were carried out on day 17, and rats were euthanized on day 24. Cell death analysis and determination of acetylcholinesterase activity was performed on the cerebral cortex and hippocampus of the brain. Administration of BRB prevented the memory loss, anxiogenic behavior, increased acetylcholinesterase activity and cell death induced by ICV-STZ. This may be explained, in part, by a protective effect of BRB on ameliorating the progression of neurodegenerative diseases, including Alzheimers disease, and the results of this study provide a better understanding of the effect of BRB on the brain. Thus, BRB may act as a potential neuroprotective agent.

Effects of chlorogenic acid on adenine nucleotides hydrolyzing enzyme activities and expression in platelets of rats experimentally demyelinated with ethidium bromide

BACKGROUNDnThe effects of chlorogenic acid (one of the major phenolic acid found in human diets) were investigated on the adenine nucleotides hydrolyzing enzymes; ecto-nucleotide pyrophosphatase/phophodiesterase (E-NPP), ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase), E-5- nucleotidase and ecto-adenosine deaminase (E-ADA) activities and expression in platelets of rats experimentally demyelinated with ethidium bromide.nnnMETHODSnRats were divided into four groups of eight animals each. Group I rats were control rats; injected with saline (CT), group II rats were injected with saline and treated with chlorogenic acid (AC), group III rats were injected with 0.1% ethidium bromide (EB) and group IV rats were injected with 0.1% EB and treated with chlorogenic acid (EB+AC). The activities of the enzymes were analyzed using colorimetric methods, and the gene expression of NTPDase 1, 2 and 3 were analyzed using the polymerase chain reaction (PCR).nnnRESULTSnThe results revealed that there was a significant (P<0.01) reduction in E-NPP activity in EB group (1.63±0.10nmol p-nitrophenol released/min/mg protein) when compared to CT group (2.33±0.14nmol p-nitrophenol released/min/mg protein). However, treatment with chlorogenic acid significantly (P<0.05) increased E-NPP activity in EB group. Furthermore, no significant (P>0.05) change was observed in the E-NPP activity of EB+AC group (2.19±0.08nmol p-nitrophenol released/min/mg protein) when compared to CT group (2.33±0.14nmol p-nitrophenol released/min/mg protein). In addition, there was a significant (P<0.05) increase in AMP hydrolysis in EB rat group when compared to CT group. No significant (P>0.05) difference was observed in AMP hydrolysis between AC, AC+EB and CT groups. Conversely, there were no significant (P>0.05) differences in ATP and ADP hydrolyses between all the groups (AC, EB, AC+EB and CT groups). Likewise, there were no significant (P>0.05) changes in E-ADA activity and percentage platelet aggregation among all groups studied. Similarly, no significant (P>0.05) change was observed in the expression of E-NTPDase 1, 2 and 3 in all the groups tested.nnnCONCLUSIONSnOur study revealed that chlorogenic acid may modulate the hydrolysis of adenine nucleotides in platelets of rats demyelinated and treated with chlorogenic acid via alteration of E-NPP and ecto-5-nucleotidase activities.

Characterization of E‐NTPDase (EC 3.6.1.5) activity in hepatic lymphocytes: A different activity profile from peripheral lymphocytes

The activity of ectonucleoside triphosphate diphosphohydrolase (E‐NTPDase; EC 3.6.1.5) was characterized in hepatic lymphocytes (HL) of rats. For this purpose, a specific method for the isolation of lymphocytes from hepatic tissue was developed. Subsequently, E‐NTPDase activity of rat HL was compared with that of rat peripheral lymphocytes. The HL showed high cell count and viability. Also, the characterization test revealed that the optimal E‐NTPDase activities were attained at 37°C and pH 8.0 in the presence of Ca2+. In addition, in the presence of specific E‐NTPDase inhibitors (20mM sodium azide and 0.3mM suramin), there were significant inhibitions in nucleotide hydrolysis. However, there was no significant change in adenosine triphosphate (ATP) or adenosine diphosphate (ADP) hydrolysis in the presence of inhibitors of other E‐ATPase (0.1mM Ouabain, 0.5mM orthovanadate, and 1mM, 5mM, and 10mM sodium azide). Furthermore, the kinetic behavior of the enzyme in HL showed apparent Km of 134.90 ± 0.03μM and 214.40 ± 0.06μM as well as Vmax of 345.0 ± 28.32 and 242.0 ± 27.55 ƞmol Pi/min/mg of protein for ATP and ADP, respectively. The Chevillard plot revealed that ATP and ADP were hydrolyzed at the same active site of the enzyme. Our results suggest that the degradation of extracellular nucleotides in HL may have been primarily accomplished by E‐NTPDase. The higher E‐NTPDase activity observed in HL may be attributed to the important physiological functions of ATP and ADP in HL.

Altered E-NTPDase/E-ADA activities and CD39 expression in platelets of sickle cell anemia patients

Sickle cell anemia (SCA) is a hemoglobinopathy characterized by hemolysis and vaso-occlusions caused by rigidly distorted red blood cells. Sickle cell crisis is associated with extracellular release of nucleotides and platelets, which are critical mediators of hemostasis participating actively in purinergic thromboregulatory enzymes system.This study aimed to investigate the activities of purinergic system ecto-enzymes present on the platelet surface as well as CD39 and CD73 expressions on platelets of SCA treated patients. Fifteen SCA treated patients and 30 health subjects (control group) were selected. Ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase), ecto-5-nucleotidase (E-5-NT) and ecto-adenosine deaminase (E-ADA) activities were measured in platelets isolated from these individuals. Results demonstrated an increase of 41 % in the E-NTPDase for ATP hydrolysis, 52% for ADP hydrolysis and 60 % in the E-ADA activity in SCA patients (P<0.05); however, a two folds decrease in the CD39 expression in platelets was observed in the same group (P<0.01). The increased E-NTPDase activity could be a compensatory mechanism associated with the low expression of CD39 in platelets. Besides, alteration of these enzymes activities suggests that the purinergic system could be involved in the thromboregulatory process in SCA patients.

Peripheral blood mononuclear cells from rat model of pleurisy: The effects of hesperidin on ectoenzymes activity, apoptosis, cell cycle and reactive oxygen species production

The present study investigates the effect of hesperidin; a flavonone commonly found in citrus fruits, on the ectoenzymes (ectonucleotidase and ecto-adenosine deaminase) activity, cell viability, apoptosis, cell cycle arrest and reactive oxygen species production in peripheral blood mononuclear cells (PBMCs) from rat model of pleurisy. Wistar rats were pretreated with either saline or hesperidin (80mg/kg) by oral gavage for 21days and injected intrapleurally with 2% carrageenan or saline on the 22nd day. PBMCs were subsequently prepared after 4h of carrageenan induction. The results revealed that hesperidin may exhibit its anti-inflammatory effects through possible modulation of ectonucleotidase (E-NTPDase) and ecto-adenosine deaminase (E-ADA) activities, reduction of intracellular reactive oxygen species, prevention of DNA damage and modulation of apoptosis as well as activation of cell cycle arrest. This study suggests some possible underlying anti-inflammatory mechanisms of hesperidin on PBMCs in acute inflammatory condition. Furthermore, hesperidin may minimize oxidative injury mediated pleurisy in rat.

Neuroprotective effects of pretreatment with quercetin as assessed by acetylcholinesterase assay and behavioral testing in poloxamer-407 induced hyperlipidemic rats

Hyperlipidemia is a group of disorders characterized by excessive lipids in the bloodstream. It is associated with the incidence of cardiovascular diseases and recognized as the most important factor underlying the occurrence of atherosclerosis. This study was conducted to investigate whether pretreatment with quercetin can protect against possible memory impairment and deterioration of the cholinergic system in hyperlipidemic rats. Animals were divided into ten groups (n=7): saline/control, saline/quercetin 5mg/kg, saline/quercetin 25mg/kg, saline/quercetin 50mg/kg, saline/simvastatin (0.04mg/kg), hyperlipidemia, hyperlipidemia/quercetin 5mg/kg, hyperlipidemia/quercetin 25mg/kg, hyperlipidemia/quercetin 50mg/kg and hyperlipidemia/simvastatin. The animals were pretreated with quercetin by oral gavage for a period of 30days and hyperlipidemia was subsequently induced by intraperitoneal administration of a single dose of 500mg/kg of poloxamer-407. Simvastatin was administered after the induction of hyperlipidemia. The results demonstrated that hyperlipidemic rats had memory impairment compared with the saline control group (P<0.001). However, pretreatment with quercetin and simvastatin treatment attenuated the damage caused by hyperlipidemia compared with the hyperlipidemic group (P<0.05). Acetylcholinesterase (AChE) activity in the cerebral hippocampus was significantly (P<0.001) reduced in the hyperlipidemic group compared with the control saline group. Pretreatment with quercetin and simvastatin treatment in the hyperlipidemic groups significantly (P<0.05) increased AChE activity compared with the hyperlipidemic group. Our results thus suggest that quercetin may prevent memory impairment, alter lipid metabolism, and modulate AChE activity in an experimental model of hyperlipidemia.

Changes in inflammatory/cardiac markers of HIV positive patients

HIV replication promotes atherogenesis and participates in the immune response to the virus, thereby influencing the inflammatory profile. These changes may, in turn, contribute to the risk of cardiovascular diseases with involvement of platelets. However, adenine nucleotides and nucleosides involved in thromboregulation and modulation of immune response may therefore be affected by these alterations.nnnOBJECTIVESnThis study sought to evaluate the profile of pro and anti-inflammatory cytokines (IL-10, IL-6, IL-17, TNF, IL-4, IL-2 and IFN-gamma), cardiac markers (troponin, CK, CK MB, LDH, CRP) in HIV-positive patients and assess the in vitro effect of antiretroviral therapy on the activities of ectonucleotidases (E-NTPDase and E-5-nucleotidase) in human platelets.nnnDESIGN AND METHODSnBlood samples were obtained from ten HIV positive patients at the Infectious Disease Clinic of the University Hospital of Santa Maria, Brazil and ten HIV negative individuals (control group) for this study.nnnRESULTSnThe results revealed that there were significant (Pxa0<xa00.05) increases in serum levels of IL-6 and IFN-gamma with no significant (Pxa0>xa00.05) changes in the serum levels of the cardiac markers investigated (CK, CK-MB, troponin, LDH and CRP). In addition, the ectonucleotidases (E-NTPDase and E-5-nucleotidase) activities were not altered (Pxa0>xa00.05) in human platelets when incubated with different antiretroviral drugs in vitro.nnnCONCLUSIONSnThe results of this study suggest that, despite successful treatment, a proinflammatory state is not altered in HIV patients, and that antiretroviral therapy per se does not change the purinergic profile.

Safety evaluation of supratherapeutic dose of Maytenus ilicifolia Mart. ex Reissek extracts on fertility and neurobehavioral status of male and pregnant rats

ABSTRACT Maytenus ilicifolia Mart. ex Reissek is a plant commonly used in folklore medicine in the management of gastric diseases in South America. This study explores the effects of a supratherapeutic dose of aqueous and ethanol extracts of M. ilicifolia (1360 mg/kg) on fertility and neurobehavioral status in male and pregnant rats. A battery of sensory‐motor developmental endpoints was carried out to assess impairments on pups of dams orally treated with the aqueous extract of M. ilicifolia during the organogenesis period of pregnancy (GD 9 through GD 14). The neuromotor maturation reflexes and physical developments of the offspring were not significantly different between the groups (p < 0.05). Also, the hippocampal morphology revealed no indices of cell loss in the CA1, CA2, CA3 and CA4 areas. As second protocol, some fertility aspects were investigated in young post pubertal male Wistar rats treated with the ethanol extract for 30 days. The semen quality and testicular tissue morphology of male rats treated with the ethanol extract of M. ilicifolia remained unaffected upon treatment. Thus, the results indicate that the high‐dose of M. ilicifolia extracts have no neurotoxic potential on offspring and seem not to affect the sperm quality of male rats. HighlightsGradual acceptance has been given to the use of Maytenus ilicifolia medicinal herb for gastric diseases in South America.Fertility and neurobehavioral assessments of M. ilicifolia extractions on pregnant and male rats were investigated here.Aqueous extract exhibited no neurotoxic potential on offspring exposed gestationally during the organogenesis.Ethanol extract did not affect the sperm quality of male rats treated for 30 days.The reproductive endpoints were not modified by the supratherapeutic dose of M. ilicifolia extracts.

Sepsis induced by cecal ligation and perforation (CLP) alters nucleotidase activities in platelets of rats

Sepsis is a potentially lethal condition, and it is associated with plateletxa0alterations. The present study sought to investigate the activity of ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase), E-5-nucleotidase, and ecto-adenosine deaminase (E-ADA) in the platelets of rats that were induced with sepsis. Male Wistar rats were divided into three groups of ten animals each: a negative control group (normal; NC); a group that underwent surgical procedures (sham); and a group that underwent cecal ligation and perforation (CLP). The induction of sepsis was confirmed by bacteremia, and the causative pathogen identified was Escherichia coli. Hematological parameters showed leukocytosis and thrombocytopenia in animals in the septic group. The results also revealed that there were significant (pxa0<xa00.05) increases in adenosine triphosphate (ATP) and adenosine monophosphate (AMP) hydrolyses, and in the deamination of adenosine in the CLP group compared to the sham and control groups. Conversely, ADP hydrolysis was significantly decreased (pxa0<xa00.05) in the CLP group compared to the sham and control groups. Purine levels were analyzed by high-performance liquid chromatography (HPLC) in serum samples from control, sham, and CLP groups. Increased concentrations of ATP, adenosine, and inosine were found in the CLP group compared to the sham and control groups. Conversely, the concentrations of ADP and AMP in the CPL group were not significantly altered. We suggest that alterations in hematological parameters, nucleotide hydrolysis in platelets, and nucleotide concentrations in serum samples of rats with induced sepsis may be related to thromboembolic events.