The Placebo Effect at the Single Cell Level.
Oppenheimer, Joshua.
2016
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Abstract: Current
drug trials and medical therapies would benefit greatly from being able to exclude
individuals who have strong responses to placebos ahead of treatment, however not enough
information about the mechanisms of the placebo effect is known at this time to be able
to distinguish between subjects easily. One possible method could be genetic screening
if a link can be established ... read morebetween a certain genotype and reaction towards the placebo
effect. However, since the placebo effect is also a learned effect, it is imperative to
identify biological markers that could distinguish strong responders from routine
responders. A way to control for the influence of learned expectations by higher thought
processing involved in the placebo effect is to eliminate that cognitive impact and
adopt a more deterministic approach. We chose to test single cells using a modification
of classical conditioning to examine whether they can respond to the placebo effect. If
a difference is found on a single cell level, it will reveal more about how much of the
placebo effect is learned and how much is influenced by changes at the cellular and
molecular level. Previous neuroimaging experiments have shown that placebo-related
expectations induce similar responses in dopaminergic release in the midbrain comparable
to dopamine response to reward processing. Two inbred strains of rats, obesity prone
(OP) and obesity resistant (OR), with differing basal and elicited levels of central
dopamine, were found to have significantly different sensitivity to the placebo effect.
Using these rats' neuroendocrine cells, we aimed to first establish a novel method of
testing whether or not a placebo effect can exist on the cellular level alone, without
the moderation of higher brain functioning. We also examined whether a difference in
basal dopamine levels influences the strength of this effect on a cellular level as it
did while part of the whole reward pathway. We report significant differences in
dopamine release of cells induced by the placebo effect in both OP (t = 2.632, p = .013)
and OR rats (t = 4.359, p < .001), with a much greater significance in the OR group.
This corroborates previous studies linking higher basal dopamine levels to the strength
of the placebo response, as well as implies that individual cells have the capacity to
alter behavior based on expectancy.
Thesis (M.S.)--Tufts University, 2016.
Submitted to the Dept. of Pharmacology & Experimental Therapeutics.
Advisor: Emmanuel Pothos.
Keywords: Pharmacology, Neurosciences, and Cellular biology.read less - ID:
- z603r904j
- Component ID:
- tufts:20482
- To Cite:
- TARC Citation Guide EndNote
