Effects of combinations of arecoline and atropine on mouse motor activity

EXPERIMENTAL STUDIES

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Pmg. Neum-Psychophomwcol. & EM. Psychiot. 1990, Vol. 14, pp. 83-90 Printed in Great Britain. All xi&s reserved

EFFECTS OF COMBINATIONS OF ARECOLINE AND ATROPINE ON MOUSE MOTOR ACTIVITY MARIA C. CASSONE,LUIGI MOLINENGO and MARCO ORSETTI Institute Of Pharmacology and Pharmacognosy, School of Pharmacy, University of Turin, Turin, Italy. (Final form, May 1989)

Abstract Cassone,Maria C.,Luigi Molinengo and Marco 0rsetti:Effectsof Combinations of Arecoline and Atropine on Mouse Motor Activity. Progr. Neuro-Psychopharmacol.& Biol. Psychiat. 1990,%:83-90 1. 2. 3. 4.

Effects on motor activity were studied after acute administration of arecoline,atropine alone and in combination in the mouse. Atropine from 15 to 45 mg/kg increased motor activity. A reduction in activity was observed at doses of arecoline above 0.2 mg/kg. An antagonism between arecoline and atropine was observed only at low doses of areco line, while higher doses of arecoline in association with atropine increased activity

Keywords:arecoline,atropine,atropine-arecolinecombination,mousemotility. Abbreviations: Acetylcholine (ACh), central nervous system (CNS).

Introduction There is ample evidence (Olds and Domino,1969; Pradham and Dutta,1970; Meltzer and Rosecrans,l982) that the cholinergic agent arecoline may antagonize some behavioral action of antimuscarinicagents atropine or scopolamine. However, in a fixed ratio schedule of reinforcement, Pradham and Dutta (1970) observed that arecoline did not antagonize the action of scopolamine and preliminary observations seem to suggest that the arecoline-atropine antagonism is manifested on the spontaneous motor activity of the mouse only

at

certain dose combination of the two drugs. The authors will now report data on the effects on motor activity in the mouse by various dose combinations of the two alkaloids.

83

M. C.Cassone et al.

a4

Materials

and Methods

Animals Albino

"Swiss Nos" mice

(Nossan S.r.1.) weighing

ZO-25g were used. The animals were

kept in cages with food and water available. Drugs

Atropine

sulfate

and arecoline

These were dissolved animals whereas Apparatus

in saline

control

saline

was divided

into 25 squares

form illumination

its cleaning.

in the subsequent

A lamp(80 watt) at a distance

activity, 3 minute

period,

crossed

four paws. All the experiments

were performed

and 30 minutes time schedule

dose or combination number

saline

Statistical To verify

the square with all

after the subcutaneous

of mouse activity

of arecoline and atropine

admini

administration

was made 15 minutes

and atropine,respectively.

were given in combination.

The same Each drug

of the same

and were tested immediately

treated with arecoline

after

or atropine.

Analysis the significance

of rather

analysis

of variance

was firstly

controls

considering

cause of variation

The results

crossed was deter-

after the subcutaneous

(0.9%) subcutaneously

the groups of animals

or eli-

of the box for

of doses was tested on at least ten mice. control groups

of mice received

or before

box 5 minutes

In this way, the evaluation

after the administration

To reduce

in the morning.

and 20 minutes

was used when arecoline

of squares

only when the animal entered

The animals were put into the experimental hydrobromide

the number

pla-

of 150 cm gave uni-

the mouse was put in the centre

mined. A square was considered

sulfate.

wall 25 cm high)

(side 7 cm). The floor was covered with a transparent

exploratory

of arecoline

to the test

was used to evaluate

of the box floor. The mice were tested individually.

the initial

Company.

(0.9%) subcutaneously.

The floor of a square box (side 35 cm,peripheral

stic sheet to facilitate

of atropine

subcutaneously

of the "open field" for rats (Brimblecombe,l963)

activity.

stration

from Sigma Chemical

Procedure

spontaneous

ten minutes;

were obtained

(0.9%). Drugs were administered

groups received

and Experimental

A modification

minate

hydrobromide

indicate

large variation

applied

between

to all the experimental the differences

that these differences

between

are not significant

the experimental data obtained the 18 control

groups, from the groups.

(F(17,190)=1.4675

P>5%).

hecoline

Then analysis ministration

of variance

was applied atropine

of arecoline,

To evaluate

in more detail

85

and atropine on mouse motor activity

to all the experimental

data obtained

and their combination.

the modifications

to estimate

the means obtained

from the drug treated mice and the corresponding

of a casual result

the statistical

caused by drug administration

t test was applied

bilities

after the ad

significance

the Student's

of the differences

between

controls.The

proba-

are given in Table 1 and Table 2.

Results The number of squares

crossed by mice in the 3 minutes

and after the administration tion are given

in Tables

of various

of experiment

doses of atropine,

arecoline

in the controls

and their combina-

1 and 2.

Table 1 Effect

Atropine

of Atropine

XiS.E.

and Arecoline

P

n

Arecoline

mg&

31.3359.69

12

Control

14.8325.2

12

30

62.50'15.54

12

9.25z3.98

12

26.91i5.89

12

9.66z1.56

12

45 Control

The means(X)

and their standard

periments(n)

and the probability

controls

and treated groups

The results

indicate

pharmacological that the various according

X+S.E.

n

P

mg/Xg

15

Control

on Mouse Motility

lo-20%

l-0.1%

3 1%

10

Control

9.7021.54

10

2

0.90+_0.52

10

errors(S.E.) of a casual

are highly

5-10%

cD.l%

10

0

10

10.50+_2.50

10

CO.l%

are given together with the number result(P)

for the differences

of ex-

between

t test).

between

significant

treatment

to the drugs or combination

10.00+2.20

10 Control

(Student's

pharmacological

5.5ot1.47

Control

that the differences

treatment

0.2

the groups which received

(F(17,190)=8.68,

caused behavioral

of drugs administered.

the various

P
modifications

which differed

11

10

10

13

12

9.025.3

12.20*3.9

74.70220.8

11.7oi4.1

Control

2

Control

5

Control

2-l%

60-70%

90%

lo-20%

P

Control

5

Control

2.50

Control

1.25

Control

19.9+ 4.5

88.8*15.1

23.1* 5.6

98.2t13.15

23.4* 8.0

71.4220.7

22.4Z6.5

17

17

12

12

12

12

10

10

(0.1%

LO.19

5-2%

70-80%

Control

12

Control

8

Control

5

Control

1

25.9i8.5

Arecoline

0.6

P mg/kg

n

on Mouse Motility

mg/kg

X+S.E.

30 mg/kg

and Atropine

Atroplne

of Arecoline

Arecoline

of Association

18.3i1.4

44.4f10.7

19.4*4.8

75.6t8.8

13.6* 3.6

56.5i13.8

12.023.9

7.5i3.8

X2S.E.

Atropine

12

12

11

11

12

12

10

10

n

P

5-2%


1%

40%

45 mg/kg

The means (X) and their standard errors (S.E.) are given together with the number of experiments (n) and the probability of a casual result (P) for the differences between controls and treated groups (Student's t test).

11

0.6

12

19.40*4.2

11.2Ot2.6

Control

12

n

15 mg/kg

18.9028.8

20.40*5.0

X2S.E.

Atropine

0.3

mglkg

Arecollne

Effects

Table 2

r,

i=

8

87

Arecoiineand atropine on mousemotoractivity

To take into account the differences between the control groups, the data of Tables 1 and 2 were transformed in percentages of the values of the corresponding control group. These percentages, given in Fig.1, indicate that 30 and 45 m&kg of atropine increased mouse motility and arecoline 2 and 10 mg/kg depressed mouse behavior.

96 Of THE

CONTROLS

c \ 360

8

+

# *

f

1

2 I+ 106 ARECOLIN iE mg/Kg

Fig 1. Effect of various doses of atropine sulfate and arecoline hydrobromide on motility House motility given in percentages of the corresponding controls. The asterisks{*) indi cate that the probabilities of a casual result for the differences to the controls (Student's t test) are less than 5%.

Arecoline 0.3, 0.6 and 2 m&kg

in association with 15 m&kg

of atropine caused no modi

fication of behavior; 5 mg/kg of arecoline plus 15 mgikgof atropine increased mouse motility. Similarly, 0.6 mg/kg Of arecoline plus 30 mg/kg of atropine caused no modifica-

M. C.Cassoneetal.

tion of mouse behavior and at 1.25, 2.5 and 5 mg/kg of arecoline in association with 30 mg/kg of atropine an increase of mouse motility was observed. Finally atropine 45mg/kg in association with 1 mg/kg of arecoline was ineffective,whilethe same dose of atropine in association with 5. 8 and 12 mg/kg of arecoline caused an evident increase of mouse motility.

Discussion The results obtained indicate that atropine causes no effect at 15 mg/kg and an increase in motor activity at 30 mg/kg. An increase of motor activity was also observed at 45 mg/kg of atropine, although this dose is l/4 of the LD50 of atropine in the mouse( MO linengo,1979). Arecoline at 0.2 mg/kg had no effect on

mouse

motility. Arecoline 2 mg/kg reduced ~KUX

motility. Mouse motility was completely abolished at 10 mg/kg of arecoline: this dose is about l/7 of the LD50 of arecoline in mouse (Molinengo and Orsetti, 1986). These observa tions are in agreement with other reports (Pradham and Dutta, 1970; Yonkov, 1985). At certain combinations of atropine plus arecoline, the changes in activity caused by the two drugs given separately disappeared. For example, 15 mg/kg of atropine (Table 2 and Fig. 11, ineffective by itself, completely removed the depressive action of 2 mg/kg of arecoline. Similarly, the stimulation caused by 30 mg/kg of atropine was suppressed by 0.6 mg/kg of arecoline. These observations are in agreement with other reports(Meltzer and Rosecrans,l982;Pradham and Dutta,1970; Nieschultz,l967) and suggest that there is an antagonism between the effects of atropine and arecoline. A stimulating action was found when doses of arecoline between 1.25 and 5 mg/kg were administered with 30 mg/kg of atropine (Table 2 and Fig 1). Similarly, doses of arecoline between 5 and 12 mg/kg gi ven in combination with 45 mg/kg of atropine caused an increase in activity. It is interesting to note that Olds and Domino (1969) observed that scopolamine (0.5 mg/kg),given with arecoline (1.6 mg/kg) facilitated self-stimulationbehavior in the rat. The fact that low doses of arecoline are adequate to suppress completely the stimulating action of atropine, suggests that the increase in motility, which we observed at higher doses of arecoline plus atropine. cannot be attributed to the stimulating action of atropine. It may also be noted that 5 mg/kg of arecoline plus 15 mg/kg of atropine caused an increase of activity,althoughthis dose of atropine by itself did not cause a significant modification of behavior. Therefore, the increased motor activity, that we

89

Arecolineand atropineon mouse motor activity

observed

in these experimental

line may have dual actions: action which becomes tempting

combe

a depressant

evident when

to correlate

stimulation

situations,

by arecoline

and Sutton,1968;

one which normally

its depressive

this dual action

exhibited

is due to arecoline.

action

of arecoline

in the superior

Tripathi,l983);

at present

This suggests

prevails

and a stimulatory

is suppressed

by atropine.

with the muscarinic cervical

ganglion

these conjectures

that areco

It is

and nicotinic

of the cat (Brimble await further

iq_dry

and support. Finally observed modify

it may be noted

that in previous

that arecoline,

the reduction

of the acetylcholine

nation

observed

are independent

(Orsetti et a1.,1987)

in the same range of doses used in present

ne in the CNS of the mouse. mouse motility

researches

may suggest

researches

from variation

researches.

did not

levels caused by 15, 30 and 45 mg/kg of atropL

These observations

in present

it has been

that the modifications

after atropine,

arecoline

of

and their combi-

of ACh levels in the CNS.

Conclusions The increased ne,suggests

motor activity,that

that arecoline

vails and a stimulatory pressed

we observed

at higher

may have dual actions:

action which becomes

doses of arecoline

a depressant

plus atropi

one which normally

evident when its depressive

action

pre-

is sup-

by atropine.

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