Increased motivation to eat in opiate-withdrawn mice.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Increased motivation to eat in opiate-withdrawn mice.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]

Know more about