Increased motivation to eat in opiate-withdrawn mice.

1. Psychopharmacology (Berl). 2012 Jun;221(4):675-84. doi:
10.1007/s00213-011-2612-x. Epub 2011 Dec 30.

Increased motivation to eat in opiate-withdrawn mice.

Rouibi K(1), Contarino A.

Author information:
(1)Addicteam, Université de Bordeaux, CNRS UMR 5287, 146 rue Léo Saignat, 33076,
Bordeaux, France.

RATIONALE: In drug-dependent individuals, the primary excessive motivation is for
drugs. Studies also indicate altered interest for « natural » rewarding activities
associated with motivational disorders that may be relevant to drug dependence.
However, to date, the impact of drug dependence and withdrawal upon motivation
for « natural » rewards remains unclear.
METHODS AND OBJECTIVES: In the present study, we use a food-driven operant
behavior paradigm to assess the impact of opiate intake and withdrawal upon the
motivational properties of highly palatable food (HPF) in mice.
RESULTS: Our findings indicate that early (8-h) opiate withdrawal does not affect
either the motivational or the discriminative properties of HPF intake. However,
starting 32 h after the last morphine injection, opiate withdrawal increases
operant behavior aimed at obtaining HPF. The increased HPF-driven behavior lasts
at least 12 days following opiate withdrawal, indicating long-lasting effects
upon motivation. Using a paradigm of reward contingency reversal, we also address
the impact of opiate withdrawal upon cognitive functions. Our results indicate
that opiate withdrawal does not affect the ability to learn a new operant rule to
obtain HPF. Indeed, opiate withdrawal ameliorates the acquisition of the new
HPF-driven operant task, most probably due to the persistent and long-lasting
increased motivation. Finally, analysis of ambulatory activity and body weight
(BW) changes reveal that motivational and cognitive effects are totally
independent of caloric and/or motor effects of opiate dosing and withdrawal.
CONCLUSIONS: These results clearly demonstrate that excessive opiate intake and
withdrawal produces dramatic and long-lasting motivational disorders relevant to
drug dependence.

DOI: 10.1007/s00213-011-2612-x
PMID: 22207240 [Indexed for MEDLINE]

Auteurs Bordeaux Neurocampus