What is meant by interactions among hormones (synergistic, antagonistic, permissive, etc.).  

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jgeertz eNotes educator| Certified Educator

Interactions among hormones can be characterized as having synergistic, permissive, or antagonistic effects.

Hormones that work in conjunction with one another are described as synergistic.

epinephrine and norepinephrine interact to increase heart rate

estrogen, prolactin, oxytocin, and cortisol all work together in  lactation  

Permissive effects occur when one hormone causes an increased sensitivity or greater activity in another hormone.

glucocorticoids increase activity of cathecholamines

uterine estrogen increases sensitivity to progesterone

Antagonistic effects are when hormones work against each other.

high levels of estrogen during pregnancy curb prolactin

insulin and glucagon inhibit each other