Fig. 8.

Scheme of neural purinergic and glutamatergic pathways involved in the vasodilation of the hindlimb in alerting defense reactions. Summary of descending projections from the hypothalamic defense area (HDA) to the brainstem and neuromodulators involved in the control of cardiovascular responses. Alerting-defense reactions increase the ATP release in the NTS that activates parallel pathways, relayed in the RVLM, involved in the withdrawal of sympathetic tone to blood vessels and epinephrine release by the adrenal gland