Palatable food stimulates neural systems implicated in drug dependence; thus sugar might have effects like a drug of abuse. Rats were given 25% glucose solution with chow for 12 h followed by 12 h of food deprivation each day. They doubled their glucose intake in 10 days and developed a pattern of excessive intake in the first hour of daily access. After 30 days, receptor binding was compared to chow-fed controls. Dopamine D-I receptor binding increased significantly in the accumbens core and shell. In contrast, D-2 binding decreased in the dorsal striatum. Binding to dopamine transporter increased in the midbrain. Opioid mu-I receptor binding increased significantly in the cingulate cortex, hippocampus, locus coeruleus and accumbens shell. Thus, intermittent, excessive sugar intake sensitized D-I and mu-I receptors much like some drugs of abuse.
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