RADA, N. M. AVENA AND B. G. HOEBEL, DAILY BINGEING ON SUGAR REPEATEDLY RELEASES DOPAMINE IN THE ACCUMBENS SHELL, Neuroscience
From juicing to going “Gluten Free,” many try to control the foods they ingest in order to remain healthy. Currently, methods of monitoring sugar intake remain popular trends in the health and diet world. However, one may not hold as much control over their diet as believed. In 2005, research at Princeton University and UCLA suggested intermittent consumption of palatable foods cause an increase in extracellular dopamine analogous to increases observed after administration of drugs and illegal substances. Subsequently, repeated consumption of palatable foods cause delays in the release of neurotransmitters involved with satiation.
In this 21-day study, rats in control groups were compared to rats intermittently allowed sugar every other twelve hours (creating a sucrose dependence). Three groups of control rats with different sucrose conditions were monitored: rats given a daily intermittent chow schedule, rats given sugar access for one hour on days 2 and 21 (yet sucrose deprived), or rats given daily access to sucrose. Rats in all control groups indicated a dampening of dopamine response during their second encounter with the sucrose solution. Dopamine dampening in 2-day and daily sucrose access groups reveal a blunting effect where if natural reward is given repeatedly, subsequent dopamine response decreases, indicating factors concerning physiological state; in comparison to experimental groups, sucrose is not held in high preference. Dopamine dampening in daily intermittent chow and sugar twice rats demonstrate not only physiological state or intermittency having legitimate influence on dopamine response – but salience as well. Sucrose depravation in both 2-day and intermittent chow groups did not suffice in preventing the blunting effect. Thus, scientists suggest a combination of intermittent feeding schedules and highly desirable or pleasant tastes contribute to consistent and increasing dopamine release in the nucleus accumbens.
Mice not given sucrose for 12 hours showed significant amounts of dopamine release (130% of baseline) within the first of 12 feeding hours. Dopamine release occurred in the rat nucleus accumbens – part of the brain central to effects of drugs and natural rewards. In addition to notably high amounts of dopamine released with sucrose access, sucrose intake also demonstrated a significant gradual increase over the three week period (from 37ml to112ml of sucrose solution per day) – both these effects of sucrose dependency are characteristics of early drug dependence. Furthermore, Acetylcholine is a neurotransmitter involved with satiation after meals, and reveals a delayed response in the nucleus accumbens of intermittent-sucrose rats – delayed acetylcholine response provides time to binge on sugar and prolongs acetylcholine increase.
Unfortunately, countless combinations of intermittent diets and various palatable foods exist and are present every day. As a result, persons may be more susceptible to sugar intake increase and subsequent sugar induced dopamine dependence than they believe. More alarming are the neurochemical and behavioral similarities between drugs of abuse and an intermittent sucrose diet. Quick neurochemical changes associated with manipulations of sucrose intake should direct awareness towards jeopardizing implications of long-term exposure to such an abundance of palatable foods, such as America’s perception of and comfort with obesity.
Rada, P., Avena, N. M., & Hoebel, B. G. (2005). Daily bingeing on sugar repeatedly releases dopamine in the accumbens shell. Neuroscience,134(3), 737-744. doi:10.1016/j.neuroscience.2005.04.043