RESUMO
Trypanosoma brucei brucei causes animal trypanosomiasis in several vertebrates and human African trypanosomiasis. Previous studies have only explored the incidence, clinical symptoms, haematology and biochemical changes associated with the disease. The behavioral manipulation hypothesis posits that parasites alter the behavior of host to increase the reproductive abilities of such parasites. Hence, the present study was carried out to investigate changes in behavior and cognition following experimental infection of T. brucei brucei in rat model. This study involved two groups of animals (uninfected control and T. brucei infected) with 8 rats per group. After confirmation of parasitaemia in the infected rats both groups were assessed to investigate if infection led to behavioral alterations and neuropathological changes using the open field, social interaction and forelimb suspension tests. Immunohistochemistry was performed on brain tissues using glial fibrillary acidic protein and anticalbindin-D28k, antibodies. We demonstrated that T. brucei infection triggered a significant decrease in exploratory activity, anxiety-like behavior, altered recognition of social novelty and reduced hanging latency in the hanging wire test. Immunohistochemistry revealed significant astrocytosis, loss of dendritic spines and reduction of Purkinje cell layer of the cerebellum. These results demonstrate that T. brucei infection induce signs of anxiety, impaired motor co-ordination with degeneration and loss of Purkinje cells.
RESUMO
BACKGROUND: Acalypha wilkesiana (Euphorbiaceae) is highly accepted for traditional treatment of human plasmodiasis in Africa. METHODS: The toxicological effects of the aqueous leaf extract of A. wilkesiana were studied in 45 male and female Wistar albino rats. An acute toxicity testing was done using 21 rats divided into seven groups and LD50 determined. In the sub-chronic toxicity study, the extract was administered orally over a period of 28 days to rats in three groups with doses of 400 mg kg-1, 800 mg kg-1 and 1,600 mg kg-1, respectively, and the fourth group administered with water served as control. Blood samples were collected for hematological and serum biochemical analysis; organs of the animals were harvested for histopathological examination. RESULTS: The acute toxicity testing showed that the extract was non-toxic at doses up to 3,000 mg kg-1 and the LD50 was calculated to be 2,828.34 mg kg-1. The study showed that at 1,600 mg kg-1 dose, the extract caused a decrease in the level of neutrophils (NEUT) while lymphocytes (LYMP) were statistically significantly increased. The administration of the extract also resulted in varying significant dose dependent increase in the levels of aspartate amino transferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP). There were also significant increases in the level of total protein (TP), urea (URN) and albumin (GLB) especially at 1,600 mg kg-1 dosage. Histopathology showed that the extract caused mild to severe significant lesions that are dose dependent in the liver and kidney when compared with the control group. CONCLUSIONS: Prolonged administration of high dose of A. wilkesiana extract has tendency to cause organ toxicity.
