Neuronal Function in Male Sprague Dawley Rats During Normal Ageing.

During normal ageing, there are physiological changes especially in high energy demanding tissues including the brain and skeletal muscles. Ageing may disrupt homeostasis and allow tissue vulnerability to disease. To establish an appropriate animal model which is readily available and will be useful to test therapeutic strategies during normal ageing, we applied behavioral approaches to study age-related changes in memory and motor function as a basis for neuronal function in ageing in male Sprague Dawley rats. 3 months, n=5; 6 months, n=5 and 18 months, n=5 male Sprague Dawley Rats were tested using the Novel Object Recognition Task (NORT) and the Elevated plus Maze (EPM) Test. Data was analyzed by ANOVA and the Newman-Keuls post hoc test. The results showed an age-related gradual decline in exploratory behavior and locomotor activity with increasing age in 3 months, 6 months and 18 months old rats, although the values were not statistically significant, but grooming activity significantly increased with increasing age. Importantly, we established a novel finding that the minimum distance from the novel object was statistically significant between 3 months and 18 months old rats and this may be an index for age-related memory impairment in the NORT. Altogether, we conclude that the male Sprague Dawley rat show age-related changes in neuronal function and may be a useful model for carrying out investigations into the mechanisms involved in normal ageing.

Biochemical changes elicited by isosaline leaf and stem-bark extracts of Harungana madagascariensis in the rat.

Isosaline leaf and stem-bark extracts of Harungana madagascariensis (L) administered intraperitoneally into healthy albino rats of the Sprague-Dawley strain at a dose of 400 mg/kg body weight resulted in a significant elevation of liver, kidney and serum alanine and aspartate aminotransferase activities. Serum urea, total proteins, total triglyceride, cholesterol, pyruvate and lactate were also significantly elevated in the treated rats. While the stem-bark extract significantly increased the blood glucose level, the leaf extract significantly lowered it. However, both extracts significantly reduced supernatant protein concentrations of the liver and kidney. The significant increase in aminotransferase activities and the concomitant reduction in protein concentrations of the liver and kidney suggests increased catabolism of proteins in these organs, while the catabolites produced are probably channelled to other metabolic pathways resulting in the observed hyperpyruvicaemia, hypertriglyceridaemia and lactic acidaemia in the treated animals. The increased serum cholesterol also suggests a probable degenerative change that these extracts may have on membranes. The results obtained clearly indicate that these extracts alter metabolic activities in both the liver and kidney of treated rats and hence, should be employed in herbal preparations with caution.

Status of phosphatase activities in the liver and kidney of rats treated with isosaline leaf and stem-bark extracts of Harungana madagascariensis (L).

The activities of phosphatases and other biochemical parameters were examined in rats treated with isosaline leaf and stem-bark extracts of Harungana madagascariensis (L). Results show that both the leaf and stem-bark extracts significantly increased the activities of serum and liver alkaline phosphatase, liver acid phosphatase, liver and kidney glucose-6-phosphatase, fructose-1,6-diphosphatase and glycogen in the treated rats. While the stem-bark extract significantly elevated the activities of fructose-1,6-diphosphatase and glycogen in the kidney, these biochemical parameters were not affected by treatment with the leaf extract. The activity of serum acid phosphatase was unaffected by the two extracts. The results obtained clearly show that these extracts caused a marked increase in gluconeogenesis in the liver and kidney of the treated rats. While the stem-bark extract increased gluconeogenesis in both liver and kidney, the leaf extract caused an increase in gluconeogenesis only in the liver. The increased serum alkaline phosphatase activity caused by these extracts may, aside from having other tissues contributing to it, be due to damage caused by these extracts to the hepatocytes. The extent of pathological changes as well as the implications of these findings to folklore medicine requires further investigation.

Effects of isosaline extracts of tetrapleura tetrapetra and olax subscorpioides on certain biochemical parameters of albino rats.

The effects of isosaline extracts of Tetrapleura tetrapetra and Olax subscorpioides were investigated in albino rats. The treatment of rats with these extracts resulted in an increase in the activities of serum alanine aminotransferase, liver aspartate aminotransferase, alanine aminotransferase, acid phosphatase and alkaline phosphatase. The extract of Tetrapleura tetrapetra caused a significant increase in blood glucose and liver glycogen levels while the extract of Olax subscorpioides caused a slight reduction but not statistically significant in the levels of blood glucose and liver glycogen. Both extracts exhibited a significant reduction of protein in the livers of treated rats.

An investigation into the biochemical basis of the observed hyperglycaemia in rats treated with ethanol root extract of plumbago zeylanica.

The effects of the ethanol extract of the root of Plumbago zeylanica on key enzymes of glycolysis and other biochemical parameters were studied in the rat. The results show that thigh muscle hexokinase, phosphofructokinase, pyruvate kinase and lactate dehydrogenase activities were significantly reduced (p < 0.05) by 12.07%, 51.02%, 24.32% and 25.16% respectively in rats treated with the ethanol extract of Plumbago zeylanica when compared with the controls. Serum pyruvate and lactate were significantly lowered in the experimental rats by 23.64% and 46.29%, respectively. The difference between the supernatant protein means was not statistically different (p > 0.05) suggesting the preservation of protein synthesis in the muscle of the extract-treated rats. The reduction in the activities of the key enzymes of glycolysis and its end-products suggests a reduction in flux across the glycolytic pathway in the extract-treated rats. This may be a result of impaired delivery to, and utilization of, glucose by the peripheral tissue, thus substantiating the reported hyperglycaemia in the extract-treated rats.