Regional expression of the anesthetic-activated potassium channel TRESK in the rat nervous system

Abstract

The two-pore-domain potassium (K(2P)) channels contribute to background (leak) potassium currents maintaining the resting membrane potential to play an important role in regulating neuronal excitability. As such they may contribute to nociception and the mechanism of action of volatile anesthetics. In the present study, we examined the protein expression pattern of the K(2P) channel TRESK in the rat central nervous system (CNS) and peripheral nervous system (PNS) by immunohistochemistry. The regional distribution expression pattern of TRESK has both similarities and significant differences from that of other K(2P) channels expressed in the CNS. TRESK expression is broadly found in the brain, spinal cord and dorsal root ganglia (DRG). TRESK expression is highest in important CNS structures, such as specific cortical layers, periaqueductal gray (PAG), granule cell layer of the cerebellum, and dorsal horn of the spinal cord. TRESK expression is also high in small and medium sized DRG neurons. These results provide an anatomic basis for identifying functional roles of TRESK in the rat nervous system.

Figure 1

Immunostaining of TRESK in the rat brain (A–C) and cerebellum (D). A control section treated with TRESK antisera that had been preabsorbed with immunizing peptide is shown in panel E. The Bregma levels of the coronal sections are determined according to the atlas of Paxinos and Watson [20]. The calibration bar represents 1 mm for all photographs. Abbreviations: Cg, cingulate cortex; M1, primary motor cortex; CPu, caudate putamen; Am, amygdala; DG, dentate gyrus; RSA, retrosplenial agranular cortex; S1, primary somatosensory cortex; ThN, thalamic nucleus; LGp, lateral globus pallidus; PyHi, pyramidal cell layer of hippocampus; GrDG, granular layer of dentate gyrus; LC, locus ceruleus; mlf, medial longitudinal fasciculus.

Figure 2

TRESK expression in brain and cerebellum at higher magnification. The calibration bars represent 0.1 mm for all photographs. Abbreviations: II, layer II; PoDG, polymorph layer of dentate gyrus; Py, pyramidal cell layer of hippocampus; CA3, field CA3 of hippocampus; Aq, Sylvius aqueduct; g, granule layer; m, molecular layer; w, white matter; Pu, Purkinje layer.

Figure 3

Immunostaining of TRESK at various levels of the rat spinal cord (low magnifications). The spinal levels are determined according to Paxinos [19]. The calibration bars represent 1 mm for all photographs. Abbreviations: C, cervical spinal cord; T, thoracic spinal cord; L, lumbar spinal cord; S, sacral spinal cord.

Figure 4

Immunostaining of TRESK in rat cervical cord (high magnification) and dorsal root ganglion (low and high magnification). The calibration bar represents 0.05 mm for the high power images only. Abbreviations: C6, cervical spinal cord segment 6.