Pharmacology Biochemistry & Behavior, Vol. 6, pp. 157-161. Copyright © 1977 by ANKHO International Inc. All rights of reproduction in any form reserved. Printed in the U.S.A.

Effects of Diazepam on Behaviour Suppressed by Extinction in Pigs' ROBERT DANTZER

LN.R.A., Laboratoire de Pharmacologie, 180 chemin de Tournefeuille 31300 Toulouse France ( R e c e i v e d 29 A u g u s t 1 9 7 6 ) DANTZER, R. Effects of diazepam on behaviour suppressed by extinction in pigs. PHARMAC. BIOCHEM. BEHAV. 6(2) 157 161, 1977. - - Diazepam injected to pigs previously trained to perform an operant response for food according to a continuous reinforcement schedule significantly increased resistance to extinction compared to control pigs. In pigs submitted to a time-out procedure diazepam increased the number of nonreinforced responses at the beginning of the acquisition but was unable to disinhibit suppressed behaviour in the later stages of acquisition when the extinguished behaviour was well acquired. The results are discussed with respect to antiaversive or disinhibitory effects of benzodiazepines and an alternative interpretation, the strengthening of the prevailing behavioural tendency in the animal's repertoire at the time of test, is put forward. Benzodiazepines Diazepam Pigs Extinction Disinhibition theory Performance facilitation

Nonreward

S E V E R A L i n t e r p r e t a t i o n s have b e e n p u t f o r w a r d to a c c o u n t for t h e strong d i s i n h i b i t o r y effects of b e n z o diazepines o n p u n i s h e d r e s p o n d i n g ranging f r o m motivational i n t e r f e r e n c e ( a n x i o l y t i c activity [28] or increase in f o o d m o t i v a t i o n [ 2 6 ] ) to a t e n d e n c y to increase low levels of r e s p o n d i n g (rate d e p e n d e n c y p r i n c i p l e [ 2 3 , 2 7 ] ) or a general d i s i n h i b i t o r y a c t i o n [19] ). T o decide b e t w e e n all these t h e o r i e s the effects of b e n z o d i a z e p i n e s o n b e h a v i o u r suppressed b y o t h e r m e a n s t h a n p u n i s h m e n t are of interest. This is especially t h e case w i t h n o n r e i n f o r c e m e n t suppressed b e h a v i o u r as it can be regarded e i t h e r as a c o n s e q u e n c e of f r u s t r a t i o n [1] or as an e x a m p l e of n o n p u n i s h e d low rate b e h a v i o u r . However a survey of the l i t e r a t u r e o n the effects of b e n z o d i a z e p i n e s o n n o n r e i n f o r c e d b e h a v i o u r reveals some i n c o n s i s t e n c i e s : while o x a z e p a m p r o d u c e d a large increase in t h e rate of n o n r e i n f o r c e d r e s p o n d i n g o f rats t r a i n e d to press a lever for s w e e t e n e d milk [ 19] and c h l o r d i a z e p o x i d e r e s t o r e d beh a v i o u r a t t e n u a t e d by n o n r e i n f o r c e m e n t in a w i t h d r a w a l p r o c e d u r e [16] or in a m o r e c o n v e n t i o n a l t i m e - o u t p r o c e d u r e [ 2 5 ] , in a n o t h e r series of e x p e r i m e n t s chlord i a z e p o x i d e was u n a b l e to affect suppressed b a r pressing in a t i m e - o u t p r o c e d u r e [20] or e x t i n g u i s h e d w a t e r i n t a k e [211. T h e p r e s e n t e x p e r i m e n t s were designed to investigate f u r t h e r the effect of a n o t h e r b e n z o d i a z e p i n e , d i a z e p a m , o n o p e r a n t b e h a v i o u r of pigs s u b m i t t e d to an e x t i n c t i o n or a time-out procedure.

Time-out

Frustration theory

EXPERIMENT 1 E x t i n c t i o n can be m e a s u r e d e i t h e r acutely b y n o m o r e r e w a r d i n g a previously learned response, or r e p e a t e d l y b y the use of a t i m e - o u t p r o c e d u r e in w h i c h o p e r a n t b e h a v i o u r is n o t r e w a r d e d d u r i n g a fixed p e r i o d of t i m e e v e n t u a l l y signalled b y an a p p r o p r i a t e e x t e r o c e p t i v e stimulus. In the first e x p e r i m e n t we e x a m i n e d the effects of a dose of d i a z e p a m k n o w n t o release b e h a v i o u r suppressed b y punishm e n t [7,9] on resistance to e x t i n c t i o n of pigs previously trained to get a food reward b y pressing a p a n e l w i t h t h e i r snout. METHOD T h i r t e e n cross-bred pigs, c a s t r a t e d male or female, were used. T h e y were 8 weeks old at the b e g i n n i n g of the e x p e r i m e n t and weighed 1 6 - 2 0 kg. The a p p a r a t u s and t h e general e x p e r i m e n t a l c o n d i t i o n s have already b e e n fully described [ 7 , 9 ] . Pigs were trained to press a panel w i t h t h e i r s n o u t to get a f o o d r e w a r d (5 g of a c o m m e r c i a l g r a n u l a r f o o d ) a c c o r d i n g to a c o n t i n u o u s r e i n f o r c e m e n t schedule, i.e. o n e r e i n f o r c e m e n t for each response. R e s p o n d i n g was c o n s i d e r e d to b e stabilized w h e n 80 r e i n f o r c e m e n t s were o b t a i n e d w i t h i n less t h a n 30 m i n in at least t h r e e successive daily sessions. O n the s u b s e q u e n t day, a single session of e x t i n c t i o n was given: the pigs were allowed to press t h e p a n e l b u t n o f o o d was available; the session e n d e d a f t e r 5 m i n w i t h o u t r e s p o n d i n g .

Many thanks are due to the skillful technical assistance of Mrs. R. M. Bluth6 and Mr. M. Caussette. 157

158

DANTZER TABLE 1

EFFECTS OF DIAZEPAM ON MEAN RESPONDING (M + SM) DURING THE EXTINCTION SESSION diaze~m~.tammted ~

s~dineo~

(n=T)

Number

of rempormel

~r~tio~

of the ~ (IN~=)

(:If e ~ o h ~ rmmond~g

2~5 1994

Of

+ 70 4 " " +. 3 g ~

79

Pm-t=ar~ o f I I R T ~ I O O s

oon~parimon

(n=6)

2.1BES +. 0 . I I 5

o f II=IT ( 10m

~

rapid d e c r e m e n t in r e s p o n d i n g as e x t i n c t i o n progressed, the d i a z e p a m g r o u p was m o r e resistant to e x t i n c t i o n and e x h i b i t e d a triphasic curve w i t h an increase in r e s p o n d i n g b e t w e e n 1 and 7 min, an i n t e r m e d i a r y rate with some o u t b u r s t s of r e s p o n d i n g from 8 24 m i n and a slow rate thereafter.

11~

DISCUSSION

26

+ I(3.4 "

F1 11

408

. L:31;2 +

F=1 11

1 ~

+ 0 19

:

g'S~

= 11.1500

4~0 = 4.840

66

I=1 11

= 5" 3190

3"1

1 Fli

= 5.3B ~

*p~

Effects of diazepam on behaviour suppressed by extinction in pigs.

Pharmacology Biochemistry & Behavior, Vol. 6, pp. 157-161. Copyright © 1977 by ANKHO International Inc. All rights of reproduction in any form reserve...
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