Roles of Adenosine Receptor (subtypes A1 and A2A) in Cuprizone-Induced Hippocampal Demyelination.

Hippocampal demyelination in multiple sclerosis (MS) has been linked with cognitive deficits, however, patients could benefit from treatment that induces oligodendroglial cell function and promotes remyelination. We investigated the role of A1 and A2A adenosine receptors (AR) in regulating oligodendrocyte precursor cells (OPCs) and myelinating oligodendrocyte (OL) in the demyelinated hippocampus using the cuprizone model of MS. Spatial learning and memory were assessed in wild type C57BL/6 mice (WT) or C57BL/6 mice with global deletion of A1 (A1AR-/-) or A2A AR (A2AAR-/-) fed standard or cuprizone diet (CD) for four weeks. Histology, immunofluorescence, Western blot and TUNEL assays were performed to evaluate the extent of demyelination and apoptosis in the hippocampus. Deletion of A1 and A2A AR alters spatial learning and memory. In A1AR-/- mice, cuprizone feeding led to severe hippocampal demyelination, A2AAR-/- mice had a significant increase in myelin whereas WT mice had intermediate demyelination. The A1AR-/- CD-fed mice displayed significant astrocytosis and decreased expression of NeuN and MBP, whereas these proteins were increased in the A2AAR-/- CD mice. Furthermore, Olig2 was upregulated in A1AR-/- CD-fed mice compared to WT mice fed the standard diet. TUNEL staining of brain sections revealed a fivefold increase in the hippocampus of A1AR-/- CD-fed mice. Also, WT mice fed CD showed a significant decrease expression of A1 AR. A1 and A2A AR are involved in OPC/OL functions with opposing roles in myelin regulation in the hippocampus. Thus, the neuropathological findings seen in MS may be connected to the depletion of A1 AR.

High Environmental Temperature: Insights into Behavioural, Neurodevelopmental and Gut Microbiome Changes Following Gestational Exposure in Rats.

Adverse effects of changing climate have been associated with increase average global temperature resulting in environmental changes. We set out to investigate effects of environmental stress due to increased heat exposure on developmental milestones, behaviour, gut microbiota and neuroarchitecture in rat pups. Pregnant Wistar rats were held in standard temperature (ST) (26 ± 2 °C; control) or high temperature (HT) (40 ± 2 °C) housing. After parturition, a cohort of the HT group and their pups were moved to the control/ST housing (gestational-only-exposed pup [GE]) while the other subset remained in the HT housing (gestational and postnatal exposed pups [GE + PE]). At different time points, we examined neurodevelopmental milestones and behaviour in the pups. Following sacrifice changes in gut microbiota, neuroarchitecture, cytokine levels (TNF-α, IL-4, IL-10), SOD, MDA, expression of MBP, NeUN and GFAP were determined. We observed impaired positioning and placing of paws, prolonged righting reflex, delayed ear opening and significant decreased body weight gain in HT pups when compared with control. We identified Firmicutes and Proteobacteria and noted a significant difference in Firmicutes count between GE and GE + PE pups at P15. Furthermore, TNF-α, IL-4, IL-10 and MDA levels were increased in GE and GE + PE pups. There was also a reduction in MBP expression in the HT pups. Taken together, our results revealed a delay in neurodevelopmental milestones in pups exposed to high HT during gestation and post natal life. Pups whose dam were exposed to high HT during gestation also showed some set back but improved over the course of testing.

Haematological Studies and Micronucleus Assay of Straw-Coloured Fruit Bats (Eidolon helvum).

The straw-coloured fruit bats (Eidolon helvum) are the most widely distributed megachiropteran species in Africa. Studies have shown that they migrate, and are likely exposed to environmental pollutants across population. This study was designed to investigate genotoxicity via the bone marrow micronucleus assay and haematological alterations of Eidolon helvum in the tropics. Healthy straw-coloured fruit bats (Eidolon helvum; n=20) were captured from two geographical regions, Ogun and Gombe States in Nigeria and were grouped based on sex and age.  Blood samples were collected for haematology and osmotic fragility, and bone marrow samples for genotoxicity studies. Results showed no significant differences in erythrocytes and leucocytes values across age and sex. The erythrocytes osmotic fragility was higher in juvenile than in adults at 0 and 0.1%NaCl, while it was higher in adult males than in adult females at 0 and 0.3% NaCl. The erythrocytes and leucocytes parameters in straw colored fruit bats were within the reference values seen in literature except the higher monocyte counts suggesting chronic inflammation. There were increased levels of micronucleated polychromatic erythrocytes and normochromatic erythrocytes in the straw-coloured fruit bats indicating genotoxicity and cytotoxicity, respectively. The present study provided baseline research data on the haematology and micronucleus profile of the straw-coloured fruit bats in Nigeria. This is perhaps the first study on haematology and micronucleus assay of in straw-colored fruit bats in the tropics.

Clofibrate, a PPAR-α agonist, abrogates sodium fluoride-induced neuroinflammation, oxidative stress, and motor incoordination via modulation of GFAP/Iba-1/anti-calbindin signaling pathways.

Fluoride is an environmental contaminant that is ubiquitously present in air, water, and soil. It is commonly added in minute quantity to drinking water, toothpaste, and mouth rinses to prevent tooth decay. Epidemiological findings have demonstrated that exposure to fluoride induced neurodevelopmental toxicity, developmental neurotoxicity, and motor disorders. The neuroprotective effect of clofibrate, a peroxisome proliferator-activated receptor alpha agonist, was investigated in the present study. Forty male Wistar rats were used for this study and randomly grouped into 10 rats per group as control, sodium fluoride (NaF) alone (300 ppm), NaF plus clofibrate (250 mg/kg), and NaF plus lisinopril (10 mg/kg), respectively, for 7 days. NaF was administered in drinking water while clofibrate and lisinopril were administered by oral gavage. Markers of neuronal inflammation and oxidative stress, acetylcholinesterase activity, and neurobehavioral (hanging wire and open field) tests were performed. Immunohistochemistry was performed on brain tissues, and they were probed with glial fibrillary acidic protein, ionized calcium-binding adaptor molecule 1, and cerebellar Ca2+ -binding protein calbindin-D28k. The results showed that NaF significantly increased of oxidative stress and neuroinflammation and inhibited AChE activity. Immunostaining showed reactive astrocytes, microgliosis, loss of dendritic spines, and arborization in Purkinje cells in rats administered only NaF. Neurobehavioral results showed that cotreatment of NaF with clofibrate improved muscular strength and locomotion, reduced anxiety, and significantly reduced astrocytic count. Overall, cotreatment of NaF with either clofibrate or lisinopril showed neuroprotective effects by mitigating neuronal inflammation and oxidative and motor incoordination. Hence, clofibrate could be seen as a novel drug candidate against neurodegeneration and motor disorders.

Behavioural studies on the ethanol leaf extract of Grewia carpinifolia in Wistar rats.

BACKGROUND: Grewia carpinifolia is a plant commonly used in the tropics to manage various central nervous system (CNS) disorders. However, despite its widespread use no scientific work has been reported to validate these claims. OBJECTIVES: To evaluate the activity of G. carpinifolia as it affects behaviour using animal model. METHODS: Twenty five adult Wistar rats were randomly divided into five groups (A-E). Group A served as control (given only distilled water), Groups B, C, D and E were administered with single oral dose of ethanol extract of G. carpinifolia leaf at 100, 200, 400 and 800 mg/kg body weight respectively for twenty eight days consecutively. Subsequently, open field test, negative geotaxis and hanging wire test were performed. Body and brain weights were measured and histological examination of the brain was also performed. RESULTS: At the tested doses, the extract significantly increased the time spent on the hanging wire and decreased locomotor activity at 800 mg/kg. No significant difference was observed in body and brain weights of extract treated groups when compared with the control. No visible histological lesion was also observed. CONCLUSION: The plant extract may improve muscular strength at tested doses and possess CNS depressant activity at 800 mg/kg.

Phytochemical and acute toxicity of ethanolic extract of Enantia chlorantha (oliv) stem bark in albino rats.

It is presumed that drugs sourced from herbs have lesser side effects than allopathic drugs. Enantia chlorantha is widely used in herbal medicine for the treatment of several ailments such as jaundice, malaria, fever, infective hepatitis, etc. However its toxicity profiles are not well documented. The effects of ethanolic extract of E. chlorantha stem bark on body weight changes, biochemical and haematological parameters as well as histology of vital organs (heart, kidneys and liver) were assessed. Also, the phytochemical constituent of the plant was analysed. Albino rats of both sexes were randomly divided into five groups (A-E) of five rats each and the ethanolic extract of E. chlorantha stem bark extract was administered by oral gavage in a single dose. Group A rats were administered 500 mg/kg of the extract, group B; 1000 mg/kg, group C; 2000 mg/kg, group D; 3000 mg/kg and group E rats received distilled water (10 ml/kg) and served as control. The extract caused significant (p<0.05) decreases in the levels of packed cell volume, haemoglobin concentration and red blood cell counts in a dose dependent manner. Further, significant alterations were not observed in the serum biochemical parameters analysed (AST, ALP, ALT, blood urea nitrogen, total protein, albumin, globulin and bilirubin). In addition, the extract at 1000, 2000 and 3000 mg/kg caused congestion in the heart and kidney of experimental rats. These results suggest that oral administration of E. chlorantha may produce severe toxic effects at relatively high doses, thus caution should be exercised in its use.