Photocell measurements of rat motor activity

Photocell Measurements A Contribution Observations

of Rat Motor Activity

to Sensitivity

and Variation

in Behavioral

EVALENAERICSON, JONNY SAMUELSSON,AND SVEN AHLENIUS

A new, photocell-equipped, served

in a large square,

vations

of rats or other

recorded

at two

activity meter is described. The motor activity is ob-

“open

field,”

similarly

levels

arena

(-0.5

sized animals.

(8 x 8 photocells

m2) suited

Horizontal

at each

level).

for activity

and vertical Information

obser-

activity from

is

each

individually fed into a microcomputer, was used to measure total motor in the periphery of the arena, forward locomotion, rearing (total and peripheral), and speed of movement. The equipment has been evaluated by photocell, activity,

activity

studying phine,

the

effects

of six psychoactive

phencyclidine,

ino) tetralin.

raclopride,

In addition,

successive

photocell

habituation

in normal

Key Words:

a graph

beam

Motor

activity;

d-amphetamine,

apomor-

and 8-hydroxy-2-(di-n-propylam-

on the distribution

interruptions,

animals

compounds,

haloperidol,

of time

and the within-

intervals

and

between

between-session

is provided. Photocells;

Open

field;

Rat

INTRODUCTION Measurement of spontaneous motor activity is perhaps the most common procedure in the evaluation of drug effects in the central nervous system of rodents (Rushton

and Steinberg,

Because the validity important

aspect.

have been

1978).

and,

and Spencer,

photocell behavior

be noted,

probably

(Dourish,

reliability

becomes

based on different

1987). Because

the most principles,

of its technical

that the environment

to this, a high degree

presented

to the animal

of intercorrelation

between

behavioral items is to be expected (Sdhle and Wold, 1986). In a recent paper, Schaefer et al. (1986) used the time between

successive

tobeam

previous

interruptions

and

equipment has gained predominance, and allows in considerable detail (Ljungberg and Ungerstedt,

however,

related

1965; KrSiak and Jankb, 1971).

is unclear,

types of equipment,

for this purpose

simplicity, of rodent

It should

is poor

Many different

described

conceptual registration

1964; Marriott

of such measurements

to calculate

speed

of movement.

Because

phodevel-

opments in this field have been concerned to a large extent with spatial and topographical aspects of the behavior, this represents an approach of great potential

From the Department and Kungsbacka Address Centre

reprint

of Neuropharmacology

MBt- and Reglerteknik requests

to:

AB, S-151 85 SbdertBlje,

Received

June 1, 1990, revised

Dr.

(E.E., S.A.), Astra Research Centre AB, S-151 85 S6dert2lje

AB (J.S.) BjdrkvPgen

Sven Ahlenius,

3, S-430 33, Fjgris,

Department

Sweden.

of Neuropharmacology,

Astra

Research

Sweden. and accepted August

1, 1990.

111 journal of Pharmacological

Methods

0 1991 Elsevier Science Publishing

25. 111-122 (1991) Co., Inc., 655 Avenue of the Americas, New York, NY 10010

112

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nm FIGURE 1. Schematic picture of the equipment of photocells (bottom).

$o,,l

(top) with an outline of the relative position

Photocell Measurements value.

Here

we describe

a new activity

meter

of Rat Motor Activities

based on photocells

where

we also

include the temporal aspect of behavioral change. The present equipment was evaluated in rats maintained under a reversed daylight cycle and measurements were made by means of infrared light sensitive photocells in the dark six small psychoactive compounds, haloperidol, lected resents

drugs

peridol

block

cordings

stimulant

Anden,

central

and B-OH-DPAT The

compounds.

with

1970;

phencyclidine

effects Vickroy

dopamine

is a centrally

results

indicate

tetralin

d-Amphetamine,

1970;

on

receptors

brain (8gren

active 5-HT receptor

dopaminergic 1982).

stimulating and

left a distinct

raclopride, were

se-

and PCP, all repneurotransmission

Raclopride

et al., 1986; Anden

of sensitivity

test compounds

(PCP),

(B-OH-DPAT)

apomorphine,

and Johnson,

a high degree

and all the different

MATERIALS

apomorphine,

B-hydroxy-2-(di-n-propylamino)

as reference

(Carlsson,

1982).

d-amphetamine,

and

agent

and

halo-

et al., 1970) (Hjorth

resolution

et al.,

in the

re-

fingerprint.

AND METHODS

Animals Adult male Sprague-Dawley rats, 280-320 g, (ALAB Laboratorietjanst, Sollentuna, Sweden) were used. The animals arrived in the laboratory at least 1 week before

-

lOOO-

3

s g500-

2

O-

0’ /

7

0 J

9

,c

$

time interval (s) FIGURE 2. Frequency distribution of time intervals between successive interruptions of photocell beams. The frequency distribution is based on the locomotor activity of 20 rats observed for 15 min. For further details see Methods.

113

114

Evalena Ericson, jenny Samuelsson, and Sven Ahlenius being used in experiments and were housed, tions of temperature (21”(I), relative humidity

5 per cage, under controlled condi(55%-65%) and 12:12 lightdark cycle

(lights off: 06.00h).

Food (R3, EWOS, Sodertalje,

Sweden)

sulphate

S.A.),

and tap waterwere

available

ad libitum.

Drugs d-Amphetamine Astra),

and phencyclidine HCI (Sigma, peridol

(Calaire

Chimie

8-hydroxy-2-(di-n-propylamino) HCI

tetralin

(PCP) (Astra) were

St Louis, MO)

was dissolved

(Janssen Pharmaceutics,

Beerse,

dissolved

subcutaneously

Belgium)

to the forms

o-3

NaCI.

NaCI.

in a minimal

with 5.5% glucose.

F7, MA),

Apomorphine

acid in 0.9%

was dissolved

of 2 ml/kg.

(Batch

(RBI, Natick,

Haloquan-

The drugs were

The doses of the drugs

refer

given above.

Motor

o.oL

in a volume

tartrate

in 0.9%

in 0.1% ascorbic

tity of glacial acetic acid and made up to volume administered

raclopride

HBr (8-OH-DPAT)

activity

I

I

3-6

6-9

Rearing

I

9-12

I

12-15

time

1

O-3

I

3-6

I

6-9

I

9-12

I

12-15

(min)

FIGURE 3. Within- and between-session habituation of motor activity in rats. The figure shows the habituation of motor activity during 15 min of observation. Indicated are the means based on repeated observations of 20 animals at 3-5-day intervals. Statistical evaluation by means of a two-way ANOVA for repeated measurements (A x B x S design) (Keppel, 1982). Motor activity: &, = 3.86, p < 0.05 (between sessions); F4,76 = 298.64, p < 0.001 (within sessions); F12,228= 2.41, p < 0.01 (between x within sessions). Rearing: F3,57 = 7.16, p < 0.01 (between sessions); f4,,G = 76.03, p < 0.001 (within sessions); F12,228= 1.01, (not sig nificant) (between x within sessions). The standard deviations were from kO.9 to +I.9 (motor activity) and from kO.3 to +I.0 (rearing).

Photocell Measurements

of Rat Motor Activities

115

Apparatus and Procedures The animals were observed in a square open field arena (680 x 680 x 450 mm) equipped with two rows of 8 photocells, sensitive to infrared light, placed 40 and 125 mm above the floor, the last photocell

respectively.

The photocells

in a row was spaced

25 mm from

were spaced 90 mm apart and the wall (Figure

1). The open

field was enclosed in a ventilated, sound-attenuating box with a perspex top. Measurements were made in the dark and performed between 09.00-16.00 hr. Interruptions of photocell beams were collected and allowed recording of the following variables.

Motor amphetamine

,o.o

5.0

*.

1

by means

of a microcomputer

activity apomorphine

raclopride

n.s. *

w x

i

1

0

8-OH-DPAT

I

o.tx3

I

I

0.12 0.5

PCP

I

2.0

I

0.0

T

‘i--u’“y ns.

*

t

ns.

o.oL

0-8

0-8 dose

(mg.kg-‘)

FIGURE 4. Effects of psychoactive compounds on motor activity in rats. The different compounds were administered S.C. at the following time intervals before observation: d-amphetamine (20 min), apomorphine (10 min), raclopride (20 min), haloperidol(40 min), 8-OHDPAT (10 min), and PCP (20 min). The observations lasted for 15 min. The results are presented as means + SD, based on observations of four to eight animals per group. Statistical evaluation by means of a one-way ANOVA, followed by the Dunnett’s t-test for comparisons with vehicle-treated confrols, as indicated in the figure (Winer 1971). NB: The locomotor activity of the vehicle-treated controls in the different experiments did not differ statistically and were, therefore, pooled in the statistical evaluation. The grand means + SD for the various groups were as follows: 9.8 + 0.4 (motor activity); 2.8 f 0.8 (rearing); 59 + 7 (peripheral motor activity); 58 f 13 (peripheral rearing); 36 2 2 (locomotion); and 21.2 f 0.8 (speed). n.s. p > 0.05, *p < 0.05, and **p < 0.01.

116

Evalena Ericson, Jenny Samuelsson, and Sven Ahlenius

1. Motor

activity:

2. Peripheral

All interruptions

motor

tobeams

activity:

of photobeams

Interruptions

in the lower

of photobeams,

spaced 25 mm from the wall in the lower

rows.

provided

that the pho-

activated. 3. Rearing: All interruptions of the photobeams in the upper rows. 4. Peripheral rearing: Interruptions of photobeams in the upper rows, provided that the photobeams

spaced

rows also were

25 mm from the wall in the upper

rows also were

activated. 5. Locomotion: animal

Successive

is moving

defined

by the photocell

the animal

interruptions

of photocells

in the same direction.

has moved

as long as the animal

being

initially,

interrupted,

and successive

rows when

are registered

indicates

The time

tion were

between

collected

successive

in O.lsec categories:

is

that

as locomotion,

The x-axis and the y-axes are registered

separately. The motor activity and rearing data were subjected to a square transformation, but quotients were calculated from the raw data. 6. Speed:

the

of the animal

the next interruption

interruptions

is moving forwards.

in the lower the location

photobeam O-0.1,

interruptions

0.2-0.3,

root

during

locomo-

. . . , 1 .I-1.2-set

(Figure

2). The median time interval was calculated from these recordings and considering the spacing of photocells, the median speed was estimated in m/min. Time and number details

of cycles recorded

are available

upon

were

request

preset

by the operator.

from the authors

Further

technical

(J.S.). For time of injections

Rearing amphetamine

apomorphine

raclopride

lO.Or

5.01

I _

n:s- n.s.

0-

E ii

haloperidol

8-OH-DPAT

0.03

.

0.0

PCP

310.0 0 E

dose FIGURE 5. Figure 4.

(mg-kg-‘)

Effects of psychoactive compounds on rearing in rats. For details see legend to

Photocell Measurements

of Rat Motor Activities

in relation to behavioral recordings see Figure legends. The total time of observations in all cases was 15 min. The statistical analysis was performed by means of appropriate one-way or two-way analysis of variance (ANOVA), as indicated in the legends to Figures 3 and 4. RESULTS

The equipment was evaluated by studying the effects of six psychoactive compounds, (d-amphetamine, apomorphine, raclopride, haloperidol, 8-OH-DPAT, and PCP) on motor activity, rearing, peripheral motor activity, peripheral rearing, locomotion and speed, as defined above. Motor

Activity

Within- and between-session habituation of motor activity is shown in Figure 3. The motor activity was suppressed in a dose-dependent manner by raclopride, haloperidol, and 8-OH-DPAT. Apomorphine and PCP produced a biphasic pattern and d-amphetamine was without statistically significant effects (Figure 4).

Peripheral

.

amphetamine

motor

activity-l

apomorphine

--Ye- .

0

L[ -fi& 0

-TW- .

0

(0100) raclopride

3.2

-

0

dose

.

2.0

.

“il:i

:-” 1.28

0-

0.8

-

0

.

18.0

(mg-kg-‘)

FIGURE 6. Effects of psychoactive compounds on peripheral motor activity in rats. The peripheral motor activity has been expressed as the percent of total motor activity. For further details see text and legend to Figure 4.

117

118

Evalena

Ericson,

Jenny Samuelsson, and Sven Ahlenius

Rearing Rearing pride,

was suppressed

haloperidol,

significant

reduction

habituation

fashion

by apomorphine,

and PCP. d-Amphetamine

produced

at the 1 mg/kg dose (Figure 5). (For within-

of rearing

Peripheral

in a dose-dependent

8-OH-DPAT,

raclo-

a statistically

and between-session

see Figure 3.)

Activity

The peripheral at the 4 mg/kg

activity was statistically dose,

whereas

the peripheral activity biphasic dose-response

PCP produced

increased

a statistically

by d-amphetamine

significant

at the 16 mg/kg dose. 8-OH-DPAT appeared curve with a statistically significant increase

eral activity

at the 0.2 mg/kg

not change

the peripheral

Peripheral

significantly

dose.

activity

Apomorphine,

raclopride,

decrease

in

to produce a of the periph-

and haloperidol

did

in the dose ranges used in this study (Figure

6).

Rearing

d-Amphetamine, apomorphine, rearing. in the peripheral

crease

raclopride, This increase

- total

Peripheral amphetamine

and

8-OH-DPAT

produced

was statistically

significant

an inat the 4

(-100)

rearing-’

raclopride

apomorphine

100

50

0i

c c

v

0

.

4.0

I

-A&- .

3.2

0

0V

0.8

0V

0

I

0.03

I

I

0.5

I

I

0.0

: haloperidol

z QlOO

50

n.s.

0i 0-%&-

.

1.28

.

dose FIGURE

7.

rearing

has been

Effects of psychoactive

at the 0.8 mg/kg text and legend

expressed

dose of 8-OH-DPAT, to Figure

4.

16.0

(mgekg-‘)

compounds

as a percent

.

.

on peripheral

.

_

of total rearing.

no value

could

..__ rearing in rats. The peripheral

NB:

Because

be calculated.

no rearing

For further

occurred

details

see

Photocell Measurements mg/kg

dose of d-amphetamine,

mg/kg dose of raclopride, and PCP did not produce ing (Figure

the 0.2-3.2

mg/kg

of Rat Motor Activities

doses of apomorphine,

the 2.0

and the 0.01-0.2 mg/kg doses of 8-OH-DPAT. Haloperidol any statistically significant changes in the peripheral rear-

7).

Locomotion &Amphetamine motion

produced

a small

but statistically

at the 1.0 and 4.0 mg/kg doses.

Raclopride

significant

increase

and PCP produced

of locomotion at the 8.0 and 16.0 mg/kg doses, respectively, which significant. 8-OH-DPAT produced a biphastic effect on locomotion, cally significant Apomorphine

increase

at the 0.05 and 0.2 mg/kg

and haloperidol

produced

doses followed

no changes

in loco-

a supression

was statistically with a statistiby a decrease.

in locomotion

(Figure

8).

Speed Apomorphine, decreases

raclopride,

of the speed

8-OH-DPAT,

at the

Locomotion

higher

-

motor

and PCP produced doses

statistically

used in this study.

activity-’

also

(-100)

apomorphine

amDhetamine

significant

Haloperidol

raclopride

OL

c

L

v

:

0

G

.

4.0

0-

.

3.2

I

I

I

0---ii?-

.

0

0.03

I

0.5

I

I

8.0

haloperidol

a100

50 :

OL

-hi&+-.

0

1.28

dose

16.0

(mgekg-‘)

FIGURE 8. Effects of psychoactive compounds on locomotion in rats. Locomotion was defined as described in Methods and expressed as a percent of total motor activity. For further details see text and legend to Figure 4.

119

120

Evalena Ericson,

Jenny Samuelsson,

and Sven Ahlenius

Speed amphetamine

raclopride

apomorphine

+$--&

2

o.oL

-we--

0

3

c

._

.

4.0

0-

haloperidol

-%he-.

3.2

.

2.0

0

8-OH-DPAT

PCP

Ck&%+

o.oL

--Tiw-.

-hii?-.

1.28

0

0

dose FIGURE

9.

defined

as described

Effects

based on single

of psychoactive in Methods

observations.

appeared

to decrease

nificant.

d-Amphetamine

compounds and expressed

For further

speed

details

of movement,

-Ye-

0.8

0

16.0

.

(mg-kg-‘) on speed of movement as m/min.

NB:

Dotted

see text and legend

but the effect

did not affect the speed

in rats. lines

Speed was

connect

to Figure

was not statistically

of movement

(Figure

values

4.

sig-

9).

COMMENTS

Results from the present evaluation has been summerized in Figure 10. The compounds have been grouped by possible mechanism of action. Thus, although the effects

on total motor

activity

was affected

pounds within the major groups, considering additional information

in the same way for some of the com-

they could all be individually on the behavior in the open

differentiated by field, and by con-

sidering the speed of movement. In conclusion, the present equipment provides both sensitivity and high resolution in behavioral measurements. Needless to say, the advantages offered by the present equipment are primarily of a quantitative nature. To improve the qualitative aspects, we need both a different type of setting, more vivarium than a packing case, and additional details of the behavior, as, for example, provided by an image analysis.

Photocell Measurements

d-Amphetamine apomorphine PCP

t 0

0

t

f

+

of Rat Motor Activities

t t

0

raclopride haloperidol

0

4

0

0

t 0

8-OH-DPAT

t

t

t

FIGURE 10.

Schematic presentation of results presented in Figures 4-9.

For excellent work on the figures and photography we would like to thank Ms. Birgitta P&son-St&e and Ms. Mandis Thunman.

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D2

discriminates motor

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Sjo-

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havioural

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Ciba

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and Com-

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RP (1986) An au-

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tivariate

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/ Pharmacol

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BJ (1971) Statistical

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