Motivational effects of
- and -opioid agonists following acute

NANCY DEL ROSARIO CAPRILES 1, LILIANA MARINA CANCELA

BEHAVIOURAL BRAIN RESEARCH

ELSEVIER SCIENCE BV

Año: 2001 vol. 132 p. 159 - 169

0166-4328

The influence of both acute and chronic restraint stress on the rewarding properties of morphine (1, 2 or 3 mg/kg i.p.) and the aversive effects of naloxone (0.5 mg/kg i.p. ×3 or 1.0 mg/kg i.p.) or bremazocine (0.4 mg/kg i.p.) was investigated. An acute (2 h) but not chronic restraint (2 h daily for 7 days) enhanced the morphine place preference, and elicited a place aversion with a subthreshold dose of bremazocine. This enhancing effect on the reinforcing properties induced by the drugs was prevented by either R(+)-SCH-23390 hydrochloride (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H3-benzazepine, 30
g//kg i.p.) and the aversive effects of naloxone (0.5 mg/kg i.p. ×3 or 1.0 mg/kg i.p.) or bremazocine (0.4 mg/kg i.p.) was investigated. An acute (2 h) but not chronic restraint (2 h daily for 7 days) enhanced the morphine place preference, and elicited a place aversion with a subthreshold dose of bremazocine. This enhancing effect on the reinforcing properties induced by the drugs was prevented by either R(+)-SCH-23390 hydrochloride (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H3-benzazepine, 30
g//kg i.p. ×3 or 1.0 mg/kg i.p.) or bremazocine (0.4 mg/kg i.p.) was investigated. An acute (2 h) but not chronic restraint (2 h daily for 7 days) enhanced the morphine place preference, and elicited a place aversion with a subthreshold dose of bremazocine. This enhancing effect on the reinforcing properties induced by the drugs was prevented by either R(+)-SCH-23390 hydrochloride (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H3-benzazepine, 30
g/R(+)-SCH-23390 hydrochloride (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H3-benzazepine, 30
g/ kg i.p.) or (
)-sulpiride (60 mg/kg i.p.), 10–20 min prior to the stress session. Naltrexone pretreatment (1 mg/kg i.p.) abolished the stress effect on morphine place preference but not that on bremazocine aversion. Instead, nor-BNI (30
g/3
l i.c.v.) abolished the stress’s effects on bremazocine aversion, but did not modify those on morphine preference. These results show that: (1) acute stress enhanced the morphine and bremazocine conditioned reinforcing effects meanwhile chronic stress did not modify them; (2) the stimulation of D1 and D2 dopamine receptors is necessary for the development of restraint stress-induced sensitization to the conditioned reinforcing effects of drugs; and (3) the stimulation of
/- and -opioid receptors seems to be differentially involved. © 2002 Elsevier Science B.V. All rights reserved.
)-sulpiride (60 mg/kg i.p.), 10–20 min prior to the stress session. Naltrexone pretreatment (1 mg/kg i.p.) abolished the stress effect on morphine place preference but not that on bremazocine aversion. Instead, nor-BNI (30
g/3
l i.c.v.) abolished the stress’s effects on bremazocine aversion, but did not modify those on morphine preference. These results show that: (1) acute stress enhanced the morphine and bremazocine conditioned reinforcing effects meanwhile chronic stress did not modify them; (2) the stimulation of D1 and D2 dopamine receptors is necessary for the development of restraint stress-induced sensitization to the conditioned reinforcing effects of drugs; and (3) the stimulation of
/- and -opioid receptors seems to be differentially involved. © 2002 Elsevier Science B.V. All rights reserved.
g/3
l i.c.v.) abolished the stress’s effects on bremazocine aversion, but did not modify those on morphine preference. These results show that: (1) acute stress enhanced the morphine and bremazocine conditioned reinforcing effects meanwhile chronic stress did not modify them; (2) the stimulation of D1 and D2 dopamine receptors is necessary for the development of restraint stress-induced sensitization to the conditioned reinforcing effects of drugs; and (3) the stimulation of
/- and -opioid receptors seems to be differentially involved. © 2002 Elsevier Science B.V. All rights reserved.1 and D2 dopamine receptors is necessary for the development of restraint stress-induced sensitization to the conditioned reinforcing effects of drugs; and (3) the stimulation of
/- and -opioid receptors seems to be differentially involved. © 2002 Elsevier Science B.V. All rights reserved.
/- and -opioid receptors seems to be differentially involved. © 2002 Elsevier Science B.V. All rights reserved.