Role of medullary GABA signal transduction on parasympathetic reflex vasodilatation in the lower lip

The Inhibition of γ-Aminobutyric Acid B1 Receptor Regulates Angiogenesis via the Hippo/YAP Signaling Pathway

Promoting the establishment of collateral circulation is essential for chronic lower extremity ischemia. However, no effective therapeutic drugs have yet been developed. Recent studies discovered that in the peripheral arteries, there are γ-aminobutyric acid B1 (GABAB1) receptors expressed in endothelial cells and smooth muscle cells, these receptors may have some effects in regulating vascular functions, but the precise mechanism is not yet clear. This study explores the effect of GABAB1 receptor inhibition on angiogenesis and its regulatory mechanism. The expression of GABAB1 in human umbilical vein endothelial cells (HUVECs) was knocked down using shRNA transfection, and effects on HUVECs' proliferation, migration, and tube formation ability were detected. Western blot and RT-PCR were used to verify the signal pathway. The murine hind limb ischemia model was used to verify the effect of CGP35348, an antagonist of GABAB1R, on the recovery of blood flow perfusion and angiogenesis in ischemic tissues. Cell proliferation, migration, and tube formation ability were improved after GABAB1 receptor knockdown in HUVECs. The phosphorylation of the HIPPO/Yes-associated protein (YAP) pathway decreased, while the effect of promoting angiogenesis increased. After treating the ischemic hindlimbs of mice with GABAB1 receptor antagonists, the blood flow perfusion recovered and the angiogenesis increased. These findings demonstrate the effect of GABAB1 receptor inhibition on the HIPPO/YAP pathway in regulating angiogenesis, suggesting that inhibiting GABAB1 receptor levels might be a novel approach for chronic lower extremity ischemia diseases.

Neurobehavioral Disorders: The Corticolimbic System in Health and Disease

The corticolimbic system (prefrontal cortices, amygdala, and hippocampus) integrates emotion with cognition and produces a behavioral output that is flexible based on the environmental circumstances. It also modulates pain, being implicated in pathophysiology of maladaptive pain. Because of the anatomic and function overlap between corticolimbic circuitry for pain and emotion, the pathophysiology for maladaptive pain conditions is extremely complex. Addressing environmental needs and underlying triggers is more important than pharmacotherapy when dealing with feline orofacial pain syndrome or feline hyperesthesia syndrome. By contrast, autoimmune limbic encephalitis requires prompt diagnosis and management with immunosuppression and seizure control.

Parasympathetic reflex vasodilation in the cerebral hemodynamics of rats

We investigated the role of parasympathetic reflex vasodilation in the regulation of the cerebral hemodynamics, and whether GABAA receptors modulate the response. We examined the effects of activation of the parasympathetic fibers through trigeminal afferent inputs on blood flow in the internal carotid artery (ICABF) and the cerebral blood vessels (rCBF) in parietal cortex in urethane-anesthetized rats. Electrical stimulation of the central cut end of the lingual nerve (LN) elicited intensity- and frequency-dependent increases in ICABF that were independent of changes in external carotid artery blood flow. Increases in ICABF were elicited by LN stimulation regardless of the presence or absence of sympathetic innervation. The ICABF increases evoked by LN stimulation were almost abolished by the intravenous administration of hexamethonium (10 mg kg(-1)) and were reduced significantly by atropine administration (0.1 mg kg(-1)). Although the LN stimulation alone had no significant effect on rCBF, LN stimulation in combination with a blocker of the GABAA receptor pentylenetetrazole increased the rCBF markedly. This increase in rCBF was reduced significantly by the administration of hexamethonium and atropine. These observations indicate that the increases in both ICABF and rCBF are evoked by parasympathetic activation via the trigeminal-mediated reflex. The rCBF increase evoked by LN stimulation is thought to be limited by the GABAA receptors in the central nervous system. These results suggest that the parasympathetic reflex vasodilation and its modulation mediated by GABA receptors within synaptic transmission in the brainstem are involved in the regulation of the cerebral hemodynamics during trigeminal afferent inputs.