GABA is the prominent inhibitory neurotransmitter in the brain and defects in the GABA system are attributable to several genetic diseases including Rett Syndrome (RTT). People with RTT show characteristic breathing disorders, suggesting a link with defects in the GABA system. Noradrenergic neurons in the locus coeruleus (LC) are CO₂ chemosensitive and play a role in breathing regulation. We conducted experiments to find out if activation of a novel group of dorsomedial LC GABAergic neurons causes instantaneous firing rate changes in LC neurons. Spike train recordings with cross-correlation analysis suggests that the dmLC neurons made monosynaptic and oligosynaptic connections with the LC neurons. The GABAergic inhibition appeared to have major effects on medullary respiratory neurons, as our results showed that THIP, the extrasynaptic GABA receptor agonist, suppressed excitations in these cells. The results from these experiments provide new evidence for the GABAergic inhibition of brainstem neurons involved in breathing control.