
Clark and von Euler ( 13) described the relationship between lung volume and breath timing in anesthetized cats. Thus it is of critical importance to maintain ventilation in the face of a variety of stimuli by adjusting the breathing pattern. The respiratory system is continually active, and any prolonged interruption is a threat to an animal's survival. The results support the hypothesis that the thalamus is a component in the respiratory mechanosensory neural pathway. These results demonstrate an immediate change in gene expression in thalamic arousal, fear, anxiety motivation-related serotonin and dopamine receptors in response to airway obstruction. Downregulation of MAPK1 may be related to the significant upregulation of HTR2A and downregulation of DRD1, suggesting an interaction in the medial thalamus serotonin-dopamine pathway elicited by airway obstruction. MAPK1 is an inhibitory regulator of HTR2A and facilitatory regulator for DRD1. The mitogen-activated protein kinase 1 (MAPK1) gene was significantly downregulated. A pathway analysis was performed that targeted serotonin and dopamine receptor pathways. A significant upregulation of the serotonin HTR2A receptor and significant downregulation of the dopamine DRD1 receptor genes were found. Following the occlusion protocol, 588 genes were found to be altered ( P < 0.05 log 2 fold change ≥ 0.4), with 327 genes downregulated and 261 genes upregulated.

Obstructions were repeated for 10 min followed by immediate dissection of the medial thalamus. The cuff was inflated to obstruct 2–4 breaths, then deflated for a minimum of 15 breaths.


Anesthetized rats were instrumented with an inflatable cuff sutured around the trachea. It was reasoned that if the thalamus is the neural gate, then tracheal obstructions will modulate the gene expression profile of the thalamus. The thalamus could be responsible for the gating of respiratory sensory information to the cortex.

Conscious awareness of breathing requires the activation of higher brain centers and is believed to be a neural gated process.
