Bacopa monniera supports the functions of the central nervous system
Mode of action of the bacosides
Anxiolytic effects of Bacopa monniera
Anti-convulsive action
Beneficial effects in the management of animal models of Alzheimer's disease
   
 
       
     
 
 
 
 
 

Bacopa monniera has been studied in animals for its purported effects on the functions of the central nervous system in its various forms, crude form, standardized extract, and compounded formulation known as Brahmi Rasayan (Table 1).

 

 
Table 1: Constituents of Brahmi Rasayan
 

Herb

Plant part used

Ratio (w/w)

Bacopa monniera

Leaves

10

Eugenia caryophyllus (cloves)

Flower

2

Piper longum (long pepper)

Stalks

1
Elettaria cardamomum (cardamom)

Seed

1

Sucrose

40
   
Beneficial effects on learning and memory:
 

Preliminary studies established the role of Brahmi in improving learning and memory capabilities. Treatment with the plant produced improvement in maze learning in albino rats.

In a detailed study, the effects of an alcoholic extract of Bacopa plant fed to rats was evaluated on the learning ability of the animals. The rats were faced with three different situations which required learning new skills and memorizing the newly learned skills. One groups of rats received Bacopa extract at a dose of 40 mg/kg/day, while the other group served as the control (untreated) group. After three consecutive days of feeding with Bacopa extract, it was observed that the treated rats significantly improved in the acquisition of new skills compared to the control group. They were also able to retain the skills acquired for the entire duration of the three-day treatment. However, the animals forgot these skills once treatment with Bacopa extract was discontinued. In order to sustain these beneficial effects, the animals had to be fed a maintenance dose of the extract for a number of days. The authors of this report suggest that Bacopa extract might facilitate learning ability in rats due to qualitative improvements in the neurons and their message-carrying connections. Based on these experiments, Bacopa was proven to exert significant but short-lived effects on memory in rats (Fig. 4.2 (a), (b)). The ease of acquisition of new skills indicated by the decrease in time taken to learn was enhanced by about 50% on treatment with Bacopa . In addition, the Bacopa treatment enhanced the retention of learning indicated by ease of "relearning" after a specific time interval by about 200%.

   
 
(a) Learning skills: ease of acquisition
 
(b)Relearning Index

Figure 4.2 The effect of Bacopa administered orally to rats on acquisition, retention and extinction of the newly learned skills
   
 

In a follow-up experiment, the same group of researchers evaluated the potential of the active saponin fractions of Bacopa monniera , Bacosides A and B, to enhance learning abilities in rats. The bacosides were fed to rats at a single dose of 10 mg/kg 90 minutes prior to teaching the animals a new skill. The treated animals were able to learn within a shorter time compared to the control group. In addition, their relearning ability was enhanced significantly even after the treatment was withdrawn. This implies that administration of bacosides improved learning abilities in the long run.

In another test, rats were taught to avoid drinking water containing lithium chloride, a chemical that causes unpleasant gastrointestinal symptoms. Rats treated with bacoside A and bacosides A & B at doses of 2.5 - 7.5 mg/kg showed a significant decrease in lithium chloride intake compared to the control group.

The results of the experiment revealed that the group of animals receiving bacoside A (I to V, fig 4.3) and bacosides A & B (VI to X, fig. 4.3) learned to avoid lithium chloride faster and in a dose dependent manner. The authors of this report commented that the positive effects of bacoside A and bacosides A & B is manifested in learning enhancement with negative reinforcement (punishment) of the newly learned skill as well as with positive reinforcement (reward) of the new skills. This is a significant finding suggesting that bacosides are effective in enhancing learning ability under two different imposed conditions, viz., punishment and reward.

Summary of dosage regimen

     
 

Group treatment

Dose of bacosides (mg/kg oral)

Bacoside A

 

I Saline

Saline 0.5 ml

II Bacoside

2.5

III Bacoside

5.0

IV Bacoside

7.5

V Bacoside

5.0 (no LiCl incubation on day 1)
 

Bacosides A and B

VI Saline

Saline 0.5 ml

VII Bacoside

2.5

VIII Bacoside

5.0

IX Bacoside

7.5

X Bacoside

5.0 (no LiCl incubation on day 1)
 
     
 

 
 

a : p <0.01; b : p < 0.05

Figure 4.3 The dose dependent effect of bacosides administered orally to rats on learning to choose sucrose drink (outer columns) rather than lithium chloride drink (inner columns)

 
     
     
 

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