Last August, I wrote a throwaway post describing an experiment in which rats presented with both sugar and cocaine demonstrated a preference for the former. This entry remained unaccountably popular for months, being hungrily linked to by all sorts of small and middling sites bearing no apparent relationship to science–in other words, kindred spirits.
So it’s time to return to the topic of how a simple compound comprising a formidable fraction of the Western world’s diet can affect behavior in lab rats, this time courtesy of a longtime Princeton psychology professor backed by a phalanx of neuroscientists. Or at least a sweet few.
Evidence of sugar’s powerfully addictive properties comes courtesy of Bart Hoebel, who has been on the Princeton faculty for an astonishing 46 years. Hoebel and his team presented their findings in Nashville, Tenn. yesterday at the American College of Neuropsychopharmacology’s annual meeting, and since I wasn;t there, I am relying on press releases and the like when I note that–at least in rats–sugar:
- is something rats, having gotten their first taste, quickly learn to “binge” on after a period of deprivation
- involves withdrawal and craving cycles that complement binges
- leads to increased alcohol consumption when its availability to binge on is terminated
- leads to lowered tolerance of amphetamines when removed from the diet
- may result in alcohol cravings when consumed binge-style
- ultimately leads to chattering teeth (seen in rats in withdrawal)
- helps beshit the Florida Everglades via the introduction of high levels of phosphate
Uppers and sugar and booze, oh my! These rats wre forced to live like Elton John did for years, but he eventually cleaned up pretty well, so I can extend them only so much pity and concern.
The researchers did not merely observe what the rats did, but studied neurochemical changes in their brains (probably a prerequisite for showing up at a neuropsychopharmacology shindig) as they cycled through sugar binges and “dry spells.” The more the rats craved sugar, the harder they hit it when given the chance and the stronger the response at the level of the nucleus accumbens, a small bundle of GABA-ergic neurons in the forebrain that are associated with reward, addiction, laughter, and fear and thus serves as the main driving force behind visits to the Chimpanzee Refuge. The NA released dopamine (a neurotransmitter associated with pleasure) in response to the rats’ guzzling of sugar water, and the more extravagant the binge, the more dopamine was released. This led to down-regulation of dopamine receptors after several weeks, so that when sugar was cut off for real and dopamine levels dropped, there were that many fewer receptors for what little dopamine remained to activate. This left the rats in a special world of bummed out.
So the overall picture may be this: Sugar consumption may not be so bad if it’s taken in frequently and at low doses. But if you’re hooked on it, then try to give it up outright, expect a ferocious rebound once you do cave in–one that may have you running for the bottle and other drugs, too. This is not at all unlike the patterns seen in human beings with bulimia nervosa, which is why Hoebel and his colleagues are excited about the potential of their work to address eating disorders at the neurochemical level.