When baboons are given thyroid hormone, their bodies develop many more of a certain type of receptor that helps respond to stress and energy signals—especially the beta-2 kind—making them much more sensitive to these signals.

We analyzed the available evidence on whether thyroid hormone increases beta-adrenergic receptor density in baboons, and what we’ve found so far leans toward yes. One assertion, supported by 13.0 studies or observations, indicates that when baboons are given thyroid hormone, their bodies develop more of a specific type of receptor—particularly the beta-2 kind—that helps cells respond to stress and energy signals. These receptors act like locks that certain hormones turn to trigger responses like increased heart rate or fat breakdown. More receptors mean the body becomes more sensitive to those signals, even if hormone levels stay the same. We did not find any studies or observations that contradicted this finding. The evidence we’ve reviewed suggests a consistent pattern: thyroid hormone appears to be linked with an increase in these receptors in baboons. However, we only reviewed one assertion, and while it is supported by a high number of observations, we cannot say whether this happens in all baboons, under all conditions, or how long the effect lasts. The number of studies cited—13.0—does not tell us if they were controlled experiments, how long they ran, or whether other factors were involved. We also don’t know if this effect is the same in humans or other animals. What this means for now is that, based on the limited evidence we’ve seen, thyroid hormone may help increase the number of these receptors in baboons, potentially making their bodies more responsive to stress and energy demands. But more research would be needed to understand how, why, and when this happens.