A study on toxic effects of sodium salicylate on rat cochlear spiral ganglion neurons: dopamine receptors mediate expressions of NMDA and GABAreceptors / 生理学报

The aim of the present study was to observe whether dopamine receptor (DR) was involved in the effects of sodium salicylate (SS) on the expressions of N-methyl-D-aspartic acid (NMDA) and γ-aminobutyric acid (GABA) receptors in rat cochlear spiral ganglion neurons (SGNs). Forty-eight hours after primary culture of rat SGNs, immunofluorescence technique was applied to detect expressions of DR1 and DR2, the two subtypes of dopamine receptors. Western blot was performed to assess NMDA receptor NR1 subunit and GABAreceptor subunit α2 (GABRα2) protein expressions in the SGNs after the treatments of SS alone or in combination with DR antagonists. The results demonstrated that: (1) The DR1 and DR2 were expressed in the bodies and axons of the SGN; (2) After the treatment with SS, the surface protein expressions of GABRα2 and NR1 were decreased by 44.69% and 21.57%, respectively, while the total protein expressions showed no significant changes; (3) Neither SS + SCH23390 (DR1 antagonist) group nor SS + Eticlopride (DR2 antagonist) group showed significant differences in GABRα2 and NR1 surface protein expressions compared with the control group. These results suggest that SS regulates the surface GABAand NMDA receptors trafficking on SGN, and the mechanism may involve DR mediation.

Interactions between dopamine receptor and NMDA/type A γ-aminobutyric acid receptors / 生理学报

Type A γ-aminobutyric acid receptors (GABAAR) and N-methyl-D-aspartate receptors (NMDAR) are the major inhibitory and excitatory receptors in the central nervous system, respectively. Co-expression of the receptors in the synapse may lead to functional influence between receptors, namely receptor interaction. The interactions between GABAAR and NMDAR can be either positive or negative. However, the mechanisms of interaction between the two receptors remain poorly understood, and potential mechanisms include (1) through a second messenger; (2) by receptors trafficking; (3) by direct interaction; (4) by a third receptor-mediation. Dopamine is the most abundant catecholamine neurotransmitter in the brain, and its receptors, dopamine receptors (DR) can activate multiple signaling pathways. Earlier studies on the interaction between DR and GABAAR/NMDAR have shown some underlying mechanisms, suggesting that DR could mediate the interaction between GABAAR and NMDAR. This paper summarized some recent progresses in the studies of the interaction between DR and NMDAR/GABAAR, providing a further understanding on the interaction between NMDAR and GABAAR mediated by DR.

Characteristics of hearing loss in 299 high-risk neonates / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To compare the occurrence of hearing loss in neonates with hyperbilirubinemia, hypoxic-ischemic encephalopathy (HIE) and very low-birth weight infant (VLBW) body mass, and to provide evidence for early intervention.</p><p><b>METHODS</b>Totally 299 high-risk neonates (598 ears) were divided into six groups: pure hyperbilirubinemia group, pure HIE group, hyperbilirubinemia with HIE group, hyperbilirubinemia with VLBW group, HIE with LBWI group, hyperbilirubinemia with VLBW and HIE mass group. Auditory brainstem response (ABR) was detected in all groups.</p><p><b>RESULTS</b>The hearing threshold of ABR and the abnormal rate of hyperbilirubinemia with LBWI and HIE were much higher than that of pure hyperbilirubinemia and pure HIE neonates.</p><p><b>CONCLUSIONS</b>Of the three high-risk factors, hearing loss occurs more often and more serious in neonates with hyperbilirubinemia and with VLBW while as HIE body mass. So the babies should receive hearing screening with ABR and be treated in time or following up as early as possible.</p>