Renin Angiotensin System (RAS) is a hormonal system that regulates blood pressure and fluid balance through a coordinated action of renal, cardiovascular, and central nervous systems. In addition to its hemodynamic regulatory role, RAS involves in many brain activities, including memory acquisition and consolidation. This review has summarized the involvement of RAS in the pathology of Alzheimer’s disease (AD), and the outcomes of treatment with RAS inhibitors. We have discussed the effect of brain RAS in the amyloid plaque (Aβ) deposition, oxidative stress, neuroinflammation, and vascular pathology which are directly and indirectly associated with AD. Angiotensin II (AngII) via AT1 receptor is reported to increase brain Aβ level via different mechanisms including increasing amyloid precursor protein (APP) mRNA, β-secretase activity, and presenilin expression. Similarly, it was associated with tau phosphorylation, and reactive oxygen species generation. However, these effects are counterbalanced by Ang II mediated AT2 signaling. The protective effect observed with angiotensin receptor blockers (ARBs) and angiotensin converting enzyme inhibitors (ACEIs) could be as the result of inhibition of Ang II signaling. ARBs also offer additional benefit by shifting the effect of Ang II toward AT2 receptor. To conclude, targeting RAS in the brain may benefit patients with AD though it still requires further in depth understanding.

Alzheimer's disease is a neurodegenerative disease characterized by deposition of extracellular amyloid-β, intracellular neurofibrillary tangles, and loss of cortical neurons. However, the mechanism underlying neurodegeneration in Alzheimer's disease (AD) remains to be explored. Many of the researches on AD have been primarily focused on neuronal changes. Current research, however, broadens to give emphasis on the importance of nonneuronal cells, such as astrocytes. Astrocytes play fundamental roles in several cerebral functions and their dysfunctions promote neurodegeneration and, eventually, retraction of neuronal synapses, which leads to cognitive deficits found in AD. Astrocytes become reactive as a result of deposition of Aβ, which in turn have detrimental consequences, including decreased glutamate uptake due to reduced expression of uptake transporters, altered energy metabolism, altered ion homeostasis (K+ and Ca+), increased tonic inhibition, and increased release of cytokines and inflammatory mediators. In this review, recent insights on the involvement of, tonic inhibition, astrocytic glutamate transporters and aquaporin in the pathogenesis of Alzheimer's disease are provided. Compounds which increase expression of GLT1 have showed efficacy for AD in preclinical studies. Tonic inhibition mediated by GABA could also be a promising target and drugs that block the GABA synthesizing enzyme, MAO-B, have shown efficacy. However, there are contradictory evidences on the role of AQP4 in AD.

Background: Societies in developing countries use traditional medicine as alternatives for management of pain and inflammation. The plant Cucumis ficifolius has been used in Ethiopia to treat many ailments including inflammation and pain. The objective of this study was to evaluate the antinociceptive and anti-inflammatory activities of the crude root extract and solvent fractions of C. ficifolius . Methods: The analgesic activity of crude extract and solvent fractions of C. ficifolius was evaluated with acetic acid-induced writhing, hot plate, and formalin-induced paw licking tests. The anti-inflammatory effect of crude methanolic root extract and solvent fractions of C. ficifolius was evaluated using carrageenan-induced paw edema. The crude extract was given at 200, 400 and 800 mg/kg. Butanol and aqueous fractions were given at 100 and 200 mg/kg doses. The negative control groups were treated with distilled water (10 mL/kg). Standard drugs used were acetylsalicylic acid (ASA) in acetic acid, formalin tests and carrageenan-induced paw edema and morphine (20 mg/kg) in hot plate test. Results: The crude extract, at its maximum dose, produced comparable analgesic activity (72.5%) to ASA in acetic acid writhing test. In the hot plate test, both the crude extract and solvent fractions exhibited a significant prolongation of nociception reaction time. Formalin test result indicated a significant reduction of mean lick time with maximal protection of 64% (early phase) and 83% (late phase). Aqueous and butanol fractions showed good analgesic activity in the three models. Inflammation was decreased by 69% with butanol (200 mg/kg); 71% (800 mg/kg) of crude extract and by 41% and 56% with the use of aqueous fraction at 100 and 200 mg/kg, respectively ( p <0.001). Conclusion: The present study indicates that the crude methanolic root extract, as well as butanol and aqueous solvent fractions, showed anti-nociceptive and anti-inflammatory activities.

Galanin (GAL) is a 29-amino-acid neuropeptide that serves multiple physiological functions throughout the central and peripheral nervous system. Its role involves in a range of physiological and pathological functions including control of food intake, neuroprotection, neuronal regeneration, energy expenditure, reproduction, water balance, mood, nociception and various neuroendocrine functions. The use of currently available antidepressant drugs raises concerns regarding efficacy and onset of action; therefore, the need for antidepressants with novel mechanisms is increasing. Presently, various studies revealed the link between GAL and depression. Attenuation of depressive symptoms is achieved through inhibition of GalR1 and GalR3 and activation of GalR2. However, lack of receptor selectivity of ligands has limited the complete elucidation of effects of different receptors in depression-like behavior. Studies have suggested that GAL enhances the action of selective serotonin reuptake inhibitors (SSRIs) and promotes availability of transcription proteins. This review addresses the role of GAL, GAL receptors (GALRs) ligands including selective peptides, and the mechanism of ligand receptor interaction in attenuating depressive symptoms.

Background. Malaria remains a major worldwide public health problem leading to death of millions of people. Spread and emergence of antimalarial drug resistance are the major challenge in malaria control. Medicinal plants are the key source of new effective antimalarial agents. Cordia africana (Lam.) is widely used for traditional management of malaria by local people in different parts of Ethiopia. The present study aimed to evaluate in vivo antimalarial effects of leaf extracts and solvent fractions of Cordia africana on Plasmodium berghei-infected mice. Methods. The leaf extracts were prepared and tested for oral acute toxicity according to the OECD guideline. In vivo antimalarial effects of various doses of C. africana extracts and solvent fractions were determined using the four-day suppression test (both crude and fractions), as well as curative and chemoprophylactic tests (crude extracts). Results. The acute toxicity test of the plant extract revealed that the medium lethal dose is higher than 2000 mg/kg. The crude extract of the plant exhibited significant parasitemia suppression in the four-day suppression (51.19%), curative (57.14%), and prophylactic (46.48%) tests at 600 mg/kg. The n-butanol fraction exhibited the highest chemosuppression (55.62%) at 400 mg/kg, followed by the chloroform fraction (45.04%) at the same dose. Conclusion. Our findings indicated that both the crude leaf extracts and fractions of C. africana possess antimalarial effects, supporting the traditional claim of the plant.