The graph shows that the administration of reserpine causes a large decrease in the mean number of revolutions performed by the mouse. The control mouse (A) performed an average of 45.20 revolutions, but the mouse that was tested 2 hours after reserpine administration (B) only performed an average of 19.20 revolutions, which is a marked reduction. The mean number of revolutions performed by the mouse tested 3 hours after administration (C) was 5.20, which is an even greater reduction in comparison to the control mouse (A). The mouse that received L-DOPA performed an average of 52.4 revolutions, which represents a small increase over the average performed by the control mouse (A). There was a somewhat large increase in locomotor activity by the mouse tested with L-DOPA following reserpine administration as it performed an average of 61.2 revolutions, which suggests the inhibitory effects of reserpine were reversed by L-DOPA.
To determine whether there is any statistical significance for any of the differences observed various 2 sampled unpaired t-tests using a 95% confidence level.
Statistical Analysis
- To determine whether there was a significant difference between the locomotor activity of the control mouse and the mouse treated with reserpine (2hrs), a 2 sample unpaired t-test was conducted with Mouse A and Mouse C.
H0: The mean number of revolutions for mouse A is equal to that of mouse B
H1: The mean number of revolutions for mouse A is not equal to that of mouse B
Mean for Mouse A = 45.20
Mean for Mouse B = 19.20
Standard deviation of Mouse A = 3.56
Standard deviation of Mouse B = 3.96
t = 10.9 Degrees of freedom = (5-1) + (5-1)
= 8
There is sufficient evidence to reject the null hypothesis and so the alternative hypothesis can be accepted, which equates to there being a significant difference between the control mouse and mouse treated with reserpine (2hrs).
- To determine whether there was a significant difference between the locomotor activity of the control mouse and the mouse treated with reserpine (3hrs), a 2 sample unpaired t-test was conducted with Mouse A and Mouse C.
H0: The mean number of revolutions for mouse A is equal to that of mouse C
H1: The mean number of revolutions for mouse A is not equal to that of mouse C
Mean for Mouse A = 45.20
Mean for Mouse C = 5.20
Standard deviation of Mouse A = 3.56
Standard deviation of Mouse C = 2.59
t = 20.3
Degrees of freedom = 8
From this test there is sufficient evidence to reject the null hypothesis which means there is a significant between the control mouse and the mouse treated with reserpine (3hrs). The alternate hypothesis can be accepted.
- From the previous t-test involving mouse A and C it can be said that the administration of reserpine had a significant effect on locomotor activity. To determine whether there was a significant difference between the locomotor activity of the control mouse and the mouse treated with L-DOPA, a 2 sample unpaired t-test was conducted with Mouse A and Mouse D.
H0: The mean number of revolutions for mouse A is equal to that of mouse D
H1: The mean number of revolutions for mouse A is not equal to that of mouse D
Mean for Mouse A = 45.20
Mean for Mouse D = 52.4
Standard deviation of Mouse A = 3.56
Standard deviation of Mouse D = 2.59
t = -1.74
Degrees of freedom = 8
In this case there is insufficient evidence to reject the null hypothesis and so the alternate hypothesis cannot be accepted. There is therefore no significant difference between the locomotor activities of the control mouse and the mouse treated with L-DOPA. L-DOPA did not have a significant effect.
- It has been shown that reserpine had a significant effect on locomotor activity whilst L-DOPA did not. To determine whether the administration of L-DOPA had a significant effect on the effects of reserpine, a 2 sample unpaired t-test was conduced with mouse C and mouse E.
H0: The mean number of revolutions for mouse C is equal to that of mouse E.
H1: The mean number of revolutions for mouse C is not equal to that of mouse E.
Mean for mouse C = 5.2
Mean for mouse E = 61.2
Standard deviation for mouse C = 2.59
Standard deviation for mouse E = 5.67
t = -11.8
Degrees of freedom = 8
There is sufficient evidence to reject the null hypothesis and so the alternate hypothesis can be accepted. There is a significant difference between the two mice. It can therefore be said that L-DOPA reversed the effects of reserpine.
Effect of drugs on rat behaviour
Table 1: showing the number of squares entered by each rat
Graph 2: showing the mean number of squares entered by each rat
The above graph shows that administration of amphetamine caused a significant increase in the activity of the rat, as the mean number of squares entered was considerably larger in comparison to the control. The average number of squares entered by the control mouse (A) was 25.2. The effect of amphetamine lessened as time passed, which can be seen by comparing rat B (75 mins) and rat C (100 mins), as the mean number of squares entered by rat B was 60 compared to 43 by rat C. It can also be seen that chloropromazine causes a marked decrease in rat behaviour. Rat D, which was given chlorpromazine following amphetamine administration, entered an average of 20.0 squares, which is slightly lower than the mean number of squares entered by the control. As it has been shown that amphetamine significantly increases rat behaviour, it is clear that chlorpromazine is reversing the effects of amphetamine administration. The inhibitory effect of chlorpromazine is confirmed with rat E, which was given only chlorpromazine and entered on average 3.6 squares. There was a marked decrease in rat activity and it appeared hesitant, which suggested catalepsy. This was confirmed with the catalepsy test in which rat E remained limply on the rod with no signs of movement, contrasting with the control rat, which moved off the rod rapidly.
Statistical Analysis
- To determine whether there was a significant difference between the control rat and the rat tested 100 minutes after D-amphetamine administration a 2 sample unpaired t-test was conducted between rat A and rat C.
H0: The mean number of squares entered by rat A is equal to the mean number of squares entered by rat C.
H1: The mean number of squares entered by rat A is not equal to the mean number of squares entered by rat C.
Mean for rat A = 25.2
Mean for rat C = 86.0
Standard deviation for rat A = 4.82
Standard deviation for rat C = 11.2
t = -11.1
Degrees of freedom = 8
There is sufficient evidence to reject the null hypothesis and so the alternate hypothesis can be accepted, which means there is a significant difference between rat A and rat C. Thus D-ampthetamine had a significant effect on locomotor activity.