Sl. Satel et al., TRYPTOPHAN DEPLETION AND ATTENUATION OF CUE-INDUCED CRAVING FOR COCAINE, The American journal of psychiatry, 152(5), 1995, pp. 778-783
Objective: Although cocaine is a potent serotonin (5-HT) reuptake bloc
ker, the role of 5-HT systems in cocaine craving and relapse in humans
has been unclear. The authors evaluated whether acute reductions in c
entral 5-HT synthesis modulated craving for cocaine in cocaine-depende
nt patients. Method: Twenty-five cocaine-dependent male inpatients wer
e exposed to cocaine-craving cues while their 5-HT levels were lowered
and during a placebo condition in a counterbalanced, double-blind des
ign. 5-HT levels were reduced by rapidly lowering plasma levels of its
precursor, tryptophan; tryptophan levels were reduced by stimulating
protein synthesis with a large drink of amino acids devoid of tryptoph
an. During the placebo condition the patients drank an identical amino
acid drink containing tryptophan. Craving was induced by exposing pat
ients to cocaine paraphernalia and a videotape depicting drug use. Cra
ving was assessed 7 hours after ingestion of the drink. Visual analog
ratings of craving for cocaine were administered before and after cue
exposure at each test session. Results: Patients reported less desire
for cocaine stimulated by cue exposure after drinking amino acids with
out tryptophan than they did after drinking placebo. The order that tr
yptophan depletion and placebo tests were performed influenced the imp
act of tryptophan depletion on cue-induced craving. Conclusions: Serot
onergic systems modulate cue-induced craving for cocaine, a factor imp
licated in relapse to cocaine use.