Role of estrogen receptor-α on food demand elasticity.
Estrogen receptor-alpha makes food reinforcers harder to lose value when prices rise.
01Research in Context
What this study did
The team used special mice that lack the estrogen receptor-alpha gene.
They let the mice press a lever for food pellets under different prices.
Each session raised the price: more lever presses needed for one pellet.
Wild-type mice kept pressing even when prices jumped.
Knockout mice quickly quit when costs went up.
What they found
Mice without estrogen receptor-alpha gave up faster when food got expensive.
Their demand curve dropped steeply, showing high elasticity.
Normal mice showed flatter curves, meaning estrogen kept demand stiff.
The hormone acts like a price buffer through this one receptor.
How this fits with other research
Dugan et al. (1995) also changed the cost of food, but used time instead of lever presses.
Both studies prove that any added cost—time or effort—shrinks demand, and biology can soften the blow.
Coburn et al. (1976) showed that rats raised in bare cages will work harder for food.
Minervini et al. (2015) adds genes to the story: hormones, not just past experience, set how hard an animal will work.
Together, these papers tell us that elasticity comes from three places: price rules, learning history, and body chemistry.
Why it matters
If you run demand-curve assessments with clients, remember that hormones sway the curve.
A teen in puberty, a woman in menopause, or anyone on hormone meds might show steeper or flatter demand than expected.
Track cycles or meds and adjust your price steps or reinforcer choices to match the real elasticity you see.
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02At a glance
03Original abstract
Estrogens have been shown to have an inhibitory effect on food intake under free-feeding conditions, yet the effects of estrogens on food-maintained operant responding have been studied to a much lesser extent and, thus, are not well understood. Therefore, the purpose of the present experiment was to use a behavioral economics paradigm to assess differences in demand elasticity between mice with knockout of the estrogen receptor subtype α, knockout of subtype β, and their wild type controls. The mice responded in a closed economy, and the price of food was increased by increasing the fixed-ratio response requirement every four sessions. Overall, we found that mice with the knockout of receptor subtype α had the most elastic demand functions. Therefore, under these conditions, estrogens increased food seeking via activation of the receptor subtype α. The results were inconsistent with those reported by previous studies that employed free-feeding conditions.
Journal of the experimental analysis of behavior, 2015 · doi:10.1017/S0033291714001834