Figure 1.

Schematic depicting afferent and efferent communication of the LC with brain regions involved in the regulation of the cardiovascular system.

Opposing CRF excitatory afferents from the CNA and ENK inhibitory afferents from the PGi regulate the function of the LC. In addition, LC efferents inhibit parasympathetic/cardioinhibitory centers (DMV and Amb) and excite the sympathoexcitatory preganglionic sympathetic neurons (PSN) and CNA. Recent findings indicate that during social defeat stress, adopting an active coping strategy (resulting in a long latency to defeat, LL) biases the LC towards PGi-ENK inhibitory afferents and a decrease in CRF afferent activation of the LC from the CNA. On the other hand, when a passive coping response (short latency to be defeated, SL) is adopted this afferent regulation of the LC is shifted towards the CNA-CRF excitatory influence and reduced PGi-ENK afferents. These data lead us to hypothesize that a bias towards either an excitatory or inhibitory input to the LC may in part underlie the basis for the individual differences in cardiovascular susceptibility seen during social defeat stress. Excitatory and inhibitory projections are denoted by a (+) or a solid line perpendicular to the projection (−).