Craig Heal
Wed, Jun-26-02, 20:56
http://www.obesityresearch.org/cgi/content/abstract/10/6/478
* Department of Psychology, Princeton University, Princeton,
New Jersey; and the Department of Physiology, University of
Los Andes, Merida, Venezuela.
Correspondence: Address correspondence to Dr. Bartley G.
Hoebel, Department of Psychology, Green Hall, Princeton
University, Princeton NJ 08544. E-mail: hoebel@princeton.edu
Objective: The goal was to determine whether withdrawal from
sugar can cause signs of opioid dependence. Because palatable
food stimulates neural systems that are implicated in drug
addiction, it was hypothesized that intermittent, excessive
sugar intake might create dependency, as indicated by
withdrawal signs.
Research Methods and Procedures: Male rats were food-deprived
for 12 hours daily, including 4 hours in the early dark, and
then offered highly palatable 25% glucose in addition to chow
for the next 12 hours. Withdrawal was induced by naloxone or
food deprivation. Withdrawal signs were measured by
observation, ultrasonic recordings, elevated plus maze tests,
and in vivo microdialysis.
Results: Naloxone (20 mg/kg intraperitoneally) caused somatic
signs, such as teeth chattering, forepaw tremor, and head
shakes. Food deprivation for 24 hours caused spontaneous
withdrawal signs, such as teeth chattering. Naloxone (3 mg/kg
subcutaneously) caused reduced time on the exposed arm of an
elevated plus maze, where again significant teeth chattering
was recorded. The plus maze anxiety effect was replicated with
four control groups for comparison. Accumbens microdialysis
revealed that naloxone (10 and 20 mg/kg intraperitoneally)
decreased extracellular dopamine (DA), while dose-dependently
increasing acetylcholine (ACh). The naloxone-induced DA/ACh
imbalance was replicated with 10% sucrose and 3 mg/kg naloxone
subcutaneously.
Discussion: Repeated, excessive intake of sugar created a
state in which an opioid antagonist caused behavioral and
neurochemical signs of opioid withdrawal. The indices of
anxiety and DA/ACh imbalance were qualitatively similar to
withdrawal from morphine or nicotine, suggesting that the rats
had become sugar-dependent.
* Department of Psychology, Princeton University, Princeton,
New Jersey; and the Department of Physiology, University of
Los Andes, Merida, Venezuela.
Correspondence: Address correspondence to Dr. Bartley G.
Hoebel, Department of Psychology, Green Hall, Princeton
University, Princeton NJ 08544. E-mail: hoebel@princeton.edu
Objective: The goal was to determine whether withdrawal from
sugar can cause signs of opioid dependence. Because palatable
food stimulates neural systems that are implicated in drug
addiction, it was hypothesized that intermittent, excessive
sugar intake might create dependency, as indicated by
withdrawal signs.
Research Methods and Procedures: Male rats were food-deprived
for 12 hours daily, including 4 hours in the early dark, and
then offered highly palatable 25% glucose in addition to chow
for the next 12 hours. Withdrawal was induced by naloxone or
food deprivation. Withdrawal signs were measured by
observation, ultrasonic recordings, elevated plus maze tests,
and in vivo microdialysis.
Results: Naloxone (20 mg/kg intraperitoneally) caused somatic
signs, such as teeth chattering, forepaw tremor, and head
shakes. Food deprivation for 24 hours caused spontaneous
withdrawal signs, such as teeth chattering. Naloxone (3 mg/kg
subcutaneously) caused reduced time on the exposed arm of an
elevated plus maze, where again significant teeth chattering
was recorded. The plus maze anxiety effect was replicated with
four control groups for comparison. Accumbens microdialysis
revealed that naloxone (10 and 20 mg/kg intraperitoneally)
decreased extracellular dopamine (DA), while dose-dependently
increasing acetylcholine (ACh). The naloxone-induced DA/ACh
imbalance was replicated with 10% sucrose and 3 mg/kg naloxone
subcutaneously.
Discussion: Repeated, excessive intake of sugar created a
state in which an opioid antagonist caused behavioral and
neurochemical signs of opioid withdrawal. The indices of
anxiety and DA/ACh imbalance were qualitatively similar to
withdrawal from morphine or nicotine, suggesting that the rats
had become sugar-dependent.