Autonomic neuroscience : basic & clinical
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Studies have shown that the dorsomedial hypothalamus (DMH) is a key region in the descending pathways mediating the cardiovascular response to emotional stress. We have recently demonstrated that the lateral/dorsolateral periaqueductal gray (l/dlPAG) is an important synaptic relay in mediating the tachycardic effect produced by activation of DMH neurons. This synaptic relay is mediated via NMDA excitatory amino acid receptors. ⋯ The tachycardic and pressor responses evoked by air jet stress paradigm were also attenuated after treatment with 8-OH-DPAT in the l/dlPAG. The increases in heart rate and arterial pressure produced by microinjection of the excitatory amino acid receptor agonist, NMDA, into the l/dlPAG were largely reduced (by 94% and 73%, respectively) after treatment in the same region with 8-OH-DPAT. Taken together, our findings indicate that 5-HT(1A) receptors at the lateral dorsolateral PAG play a significant role in modulating the descending cardiovascular pathways from the dorsomedial hypothalamus and consequently the cardiovascular response to emotional stress.