Octopamine is a naturally occurring monoamine that is structurally related to norepinephrine and functions as a neurotransmitter, neuromodulator, and hormone in many invertebrates. In mammals, including humans, octopamine is present but at much lower concentrations. Its primary sympathomimetic effects are mediated via stimulation of adrenergic receptors, particularly the beta-3 subtype, which can lead to mild increases in heart rate, blood pressure, and lipolysis. These effects are relevant to the sympathetic nervous system, which orchestrates the body's "fight or flight" response.

The scientific evidence supporting octopamine’s use to support the sympathetic nervous system is limited. Some animal studies and in vitro experiments suggest octopamine can elicit sympathetic-like responses, but the potency is significantly less than that of endogenous catecholamines like norepinephrine. In humans, octopamine has occasionally been used as a component in weight loss supplements, purportedly for its mild stimulatory effects. However, clinical studies in humans are sparse and the physiological impact appears to be modest at best. Regulatory agencies such as the FDA have also raised safety concerns about octopamine-containing supplements, particularly due to potential cardiovascular effects.

In summary, while there is some scientific rationale based on its pharmacology and limited animal/human studies, the quality and quantity of evidence supporting octopamine as a sympathetic nervous system supporter is low.