Evaluation of relationship between the Centella asiatica (Linn) fresh leaf extract induced spatial learning and memory enhancement and increased body weight gain in neonatal and adult rats
K Rao, S Rao, S Rao
adult rats, body weight gain, memory retention, neonatal rats, spatial learning
K Rao, S Rao, S Rao. Evaluation of relationship between the Centella asiatica (Linn) fresh leaf extract induced spatial learning and memory enhancement and increased body weight gain in neonatal and adult rats. The Internet Journal of Alternative Medicine. 2007 Volume 5 Number 2.
Ayurveda, an alternative system of medicine practiced widely in India, uses a number of plants for treatment of variety of diseases.
Thus, this study was designed to find the effect of different doses of CeA fresh leaf extract for different durations on the body weight in neonatal and adult rats. And correlate the body weight with the enhanced spatial learning and memory retention power reported earlier in these rats. In the present study, we have aimed to conduct the experiment in the same way as explained in the classic texts of Ayurveda (5), i.e. without going for extraction, but using the fresh leaf extract.
The experiment was conducted in two major groups. In the first group, neonatal rat pups (7 days old) of both sexes and in the second group, adult rats (2.5 month old) of both sexes were used. Rats of both the groups were bred and maintained in our central research animal facility. They were fed with food and water adlibitum and maintained in 12:12 hours dark and light cycle. The room temperature was kept constant at 25oC throughout the experimental period. All the experiments were carried out with prior approval from the institutional animal ethical committee and only minimum required number of rats were used and handled in humane way.
Rats of each major group were assigned into three minor groups of two, four and six week treatment. Rats in each of these groups were divided into 2ml/kg (CeA 2ml), 4ml/kg (CeA 4ml) and 6ml/kg (CeA 6ml) body weight dose groups (n=8 for each dose). Each rat in the given dosage group was fed through gastric intubation with given amount of fresh leaf extract of
Extraction and administration of Centella asiatica fresh leaf extract
Since standard extraction procedures, which involve boiling in water, ethyl alcohol or other organic solvents, may alter the structure of bioactive principles, we have avoided standard extraction protocols. Though there may be a minor variation in daily preparations, it will be minimal as leaves of equal maturation are collected from the same place on all days. This minor daily variation will be compensated by long period (2, 4 and 6 weeks) of treatment. It has been shown in a recent literature that Centella
Recording the body weight
The initial body weight of the rats of all the groups was recorded before the beginning of the treatment with CeA fresh leaf extract. There after the body weight of the rats of all the groups was recorded at the end of every week. The net body weight gain was calculated for each rat at the end of 2 weeks, 4 weeks and 6 weeks after the beginning of administration of CeA fresh leaf extract using the following formula.
Net body weight gain = Weight of the animal at the end of treatment period (2, 4 and 6 weeks) - Initial weight
Further, the weight gained by the rats treated with different doses (2, 4 and 6ml) of fresh leaf extract of CeA for different durations (2, 4 and 6 weeks) was compared with the dose and duration matched normal and saline control rats. Results of the body weight gain are then compared with the results of the behavioral experiments of the different groups reported earlier (13, 14).
Data was analyzed using analysis of variance (ANOVA) followed by Bonferroni's post test using Graph Pad in Stat (GPIS) software, version 1.13.
The rats treated with
Body weight gain in neonatal group of rats
Results of 6 weeks treatment group (Figure 2)
The rats belonging to all the three (2, 4 and 6ml) dose groups showed a significant increase in the body weight gain. [66.57 ± 5.72 g. in normal control vs 86.0 ± 6.4 g. in CeA 2ml group (29.17% increase), P< 0.05; 90.12 ± 13.89 g. in CeA 4ml group (35.37 % increase), P< 0.01 and 97.25 ± 8.48 g. in CeA 6ml (46.08% increase), P< 0.001].
Results of 4 weeks treatment group (Figure 3)
The rats belonging to all the three (2, 4 and 6ml) dose groups showed a significant increase in the body weight gain. [55.25 ± 6.38 g. in normal control vs 66.55 ± 4.55 g. in CeA 2ml group (20.45% increase), P< 0.05; 72.58 ± 5.63 g. in CeA 4ml group (31.36 % increase), P< 0.001 and 85.57 ± 2.56 g. in CeA 6ml (54.87% increase), P< 0.001].
Results of 2 weeks treatment group (Figure 4)
There was no significant change in the body weight in the group treated with 2ml CeA fresh leaf extract. Only the rats belonging to 4 and 6ml dose groups showed a significant increase in the body weight gain. [13.34 ± 2.68 g. in normal control vs 33.21 ± 1.66 g. in CeA 4ml group (148.95% increase), P< 0.001 and 37.9 ± 1.96 g. in CeA 6ml (184.1% increase), P< 0.001].
Body weight gain in adult group of rats
Results of 6 weeks treatment group (Figure 5)
The rats belonging to only 6ml dose group showed a significant increase in the body weight gain [54.14 ± 20.51g. in normal control vs 78.66 ± 15.99 g. in CeA 6ml (45.28% increase), P< 0.01]. The lower dose groups (2 and 4ml) did not show any significance difference in the body weight gain compared to the normal control rats.
Results of 4 weeks treatment group
There was no significant change in the body weight gain in rats treated with CeA for 4 weeks in any of the dose (2, 4 and 6ml/kg) groups (data not illustrated).
Results of 2 weeks treatment group:
There was no significant change in the body weight gain in rats treated with CeA for 2 weeks in any of the dose (2, 4 and 6ml/kg) groups (data not illustrated).
In the neonatal group, treatment with higher dose (6ml/day/kg body weight) of
As reported earlier (13, 14),
Results of Spatial learning (T- maze) tests of neonatal group of rats
Results of Passive avoidance tests of neonatal group of rats
Results of Spatial learning T- maze and passive avoidance memory retention tests of adult 6 weeks group of rats.
Though the spatial learning and memory enhancing effect of CeA has been reported before (13, 14), there is no report on its effect directly on the body weight. The increase in the body weight gain may be because of the role of CeA in increasing physical strength and digestive power and its antiemaciatic effect (1,3,16). CeA enhances the digestive power, may be through its anti protozoal activity against entamoeba histolytica (17). In addition, there are reports of administration of aqueous extract CeA restoring the body weight loss, due to radio therapy (18). A number of modern scientists have proved that this plant is useful in a number of disorders including wound healing (19, 20). In addition, extract of CeA was shown to stimulate extra-cellular matrix accumulation around experimental wounds in rats (21). Healing of wounds, involves the activity of an intricate network of blood cells, tissue types, cytokines, and growth factors. This results in increased cellular activity, which causes an intensified metabolic demand for nutrients. Several nutritional factors and vitamins are required for wound repair. Adequate dietary protein is absolutely essential for proper wound healing, and tissue levels of the amino acids arginine and glutamine may influence wound repair and immune function (22). Such properties of Centella asiatica may also be responsible for the increased body weight. In addition to its positive effect on body weight, CeA has also shown its positive effect on increasing learning ability, memory retention power (13, 14), and dendritic arborization of hippocampal CA3 and amygdaloid neurons (23, 24, 25) of these rats. This relationship between the body weight gain and the improved behavior and structural changes in the hippocampal neurons of the rats supports the view that physical wellbeing and mental wellbeing are related to each other.
To conclude, we state that the oral administration of fresh leaf extract of
Dr. Mohandas Rao K. G., Assistant Professor of Anatomy Faculty of Medicine and Health Sciences, AIMST University DSemeling 08100, Bedong, Kedah Darul Aman, Malaysia Office: 06-04-4298000 Ext: 3003 Hand phone: +60164977261 E-mail: firstname.lastname@example.org