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Effects of arginine-vasopressin on retention and forgetting in appetitive tasks
Behavioural Brain Research, 16 (1985) 185-237 Elsevier
185
EFFECTS OF ARGININE-VASOPRESSIN ON RETENTION AND FORGETTING IN APPETITIVE TASKS ALESClO, B., ROMAN, F. AND SOUMIREU-MOURAT, B. Neurobiologie des Comportements, Universit~ de Provence, Centre de St. J~r6me, 13397 M a r s e i l l e Cedex 13, France The present experiments examined the e f f e c t s of peripheral a d m i n i s t r a t i o n of arginine-vasopressin on learned behavior, in order to determine whether or not they concern memory processes, retent i o n and r e t r i e v a l . In a p r e l i m i n a r y experiment, we studied the rate of f o r g e t t i n g of a Go-NoGo a p p e t i t i v e d i s c r i m i nation task. BALB/c male mice underwent during 3 days a d a i l y session of l e a r n i n g , in order to d i s cr im in a t e between two p a r a l l e l runways (one white, one dark); every day, 12 randomized t r i a l s were run (6 S+, 6 S-); h a l f of the animals were reinforced on the white side, the other h a l f on the dark side. A 4th session was run according to the groups between one day and 30 days a f t e r the 3rd l e a r n ing session. Retention performance on t h i s test session was continuously decreasing when the delay increased, and a f o r g e t t i n g curve was observed. For the f o l l o w i n g experiments, we chose to t e s t the animals 24 days a f t e r the 3rd learning session, since f o r t h i s time i n t e r v a l , performance is c l e a r l y reduced, but the subjects d o n ' t f o r g e t completely the d i s c r i m i n a t i o n : so a treatment would be able to produce e i t h e r an improvement or a disturbance. The treatment consisted of a subcutaneous i n j e c t i o n of arginine-vasopressin (AVP) at one of two doses: I u g or 0 . 5 ~ g in 0.5 ml of s a l i n e . In the f i r s t
experiment, AVP was injected j u s t a f t e r the
end of the I s t learning session. Control subjects were injected with s a l i n e in the same c o n d i t i o n s . Compared to c o n t r o l s , r e t e n t i o n of AVP subjects was improved on the 2nd l e a r n i n g session, and the e f f e c t was c l e a r e r with the I ~g than with the 0 . 5 ~ g dose. All the subjects were tested 24 days a f t e r the 3rd learning session, without a d d i t i o n a l treatment: performance of the treated mice was still
b e t t e r than the c o n t r o l s ' one,even though we observed a p a r t i a l f o r g e t t i n g f o r a l l subjects. In another experiment, AVP was injected - j u s t f o r the I s t time - 30 minutes before the test
session (24th day a f t e r the 3rd learning session). With the 1~g dose, AVP c l e a r l y improved performance, i . e . kept about the same l e v e l of performance as on the 3rd day of l e a r n i n g ; in the same time, c o n t r o l s presented a marked rate of f o r g e t t i n g . The 0 . 5 ~ g dose of AVP did not produce any e f f e c t . These re s u l t s seem to i n d i c a t e that vasopressin was d i r e c t l y a c t i v e on memory processes, as we observed an improvement of r e t e n t i o n and a reduction of f o r g e t t i n g in an a p p e t i t i v e d i s c r i m i n a t i v e task. However, other experiments have to be run, using other doses and other behavioral tasks in order to test the g e n e r a l i t y of our r e s u l t s ; indeed, there is a l o t of controversy concerning the nature of e f f e c t s of AVP on learned behaviors.
185
EFFECTS OF ARGININE-VASOPRESSIN ON RETENTION AND FORGETTING IN APPETITIVE TASKS ALESClO, B., ROMAN, F. AND SOUMIREU-MOURAT, B. Neurobiologie des Comportements, Universit~ de Provence, Centre de St. J~r6me, 13397 M a r s e i l l e Cedex 13, France The present experiments examined the e f f e c t s of peripheral a d m i n i s t r a t i o n of arginine-vasopressin on learned behavior, in order to determine whether or not they concern memory processes, retent i o n and r e t r i e v a l . In a p r e l i m i n a r y experiment, we studied the rate of f o r g e t t i n g of a Go-NoGo a p p e t i t i v e d i s c r i m i nation task. BALB/c male mice underwent during 3 days a d a i l y session of l e a r n i n g , in order to d i s cr im in a t e between two p a r a l l e l runways (one white, one dark); every day, 12 randomized t r i a l s were run (6 S+, 6 S-); h a l f of the animals were reinforced on the white side, the other h a l f on the dark side. A 4th session was run according to the groups between one day and 30 days a f t e r the 3rd l e a r n ing session. Retention performance on t h i s test session was continuously decreasing when the delay increased, and a f o r g e t t i n g curve was observed. For the f o l l o w i n g experiments, we chose to t e s t the animals 24 days a f t e r the 3rd learning session, since f o r t h i s time i n t e r v a l , performance is c l e a r l y reduced, but the subjects d o n ' t f o r g e t completely the d i s c r i m i n a t i o n : so a treatment would be able to produce e i t h e r an improvement or a disturbance. The treatment consisted of a subcutaneous i n j e c t i o n of arginine-vasopressin (AVP) at one of two doses: I u g or 0 . 5 ~ g in 0.5 ml of s a l i n e . In the f i r s t
experiment, AVP was injected j u s t a f t e r the
end of the I s t learning session. Control subjects were injected with s a l i n e in the same c o n d i t i o n s . Compared to c o n t r o l s , r e t e n t i o n of AVP subjects was improved on the 2nd l e a r n i n g session, and the e f f e c t was c l e a r e r with the I ~g than with the 0 . 5 ~ g dose. All the subjects were tested 24 days a f t e r the 3rd learning session, without a d d i t i o n a l treatment: performance of the treated mice was still
b e t t e r than the c o n t r o l s ' one,even though we observed a p a r t i a l f o r g e t t i n g f o r a l l subjects. In another experiment, AVP was injected - j u s t f o r the I s t time - 30 minutes before the test
session (24th day a f t e r the 3rd learning session). With the 1~g dose, AVP c l e a r l y improved performance, i . e . kept about the same l e v e l of performance as on the 3rd day of l e a r n i n g ; in the same time, c o n t r o l s presented a marked rate of f o r g e t t i n g . The 0 . 5 ~ g dose of AVP did not produce any e f f e c t . These re s u l t s seem to i n d i c a t e that vasopressin was d i r e c t l y a c t i v e on memory processes, as we observed an improvement of r e t e n t i o n and a reduction of f o r g e t t i n g in an a p p e t i t i v e d i s c r i m i n a t i v e task. However, other experiments have to be run, using other doses and other behavioral tasks in order to test the g e n e r a l i t y of our r e s u l t s ; indeed, there is a l o t of controversy concerning the nature of e f f e c t s of AVP on learned behaviors.