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Acid‐sensitive ion channels (ASICs) in the lamina terminalis of rat brain
Author(s) -
Abrams Joanna Mariam,
Engeland William C.,
Palmer Melissa L.,
O'Grady Scott M.,
Osborn John W.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.lb37-b
Subject(s) - lamina terminalis , subfornical organ , circumventricular organs , acid sensing ion channel , epithelial sodium channel , medicine , endocrinology , hypertonic saline , immunohistochemistry , biology , chemistry , ion channel , receptor , sodium , central nervous system , angiotensin ii , organic chemistry
Studies have shown that intracerebroventricular (ICV) administration of benzamil prevents pressor response to ICV hypertonic saline and chronic salt‐sensitive models of hypertension. However, the specific channels targeted and their location within osmosensitive brain structures are unknown. Benzamil blocks Epithelial Sodium Channels (ENaCs), as well as Acid‐sensitive Ion Channels (ASICs). Therefore, quantitative reverse‐transcriptase PCR (QRT‐PCR) experiments were conducted using primers generated for the subunits of these channels on key brain regions collected in 300 μM sections. Primers were generated for the δENaC channel, which has been found in primate CNS, and to ASICs1, 2, & 3. QRT‐PCR results suggest that ASIC2 message is present in the lamina terminalis (LT; CT = 21 cycles with single peak dissociation curve at 83 ° C). To assess whether ASIC2 protein was present in the LT, immunohistochemistry (IHC) studies were conducted. Preliminary IHC results suggest that ASIC2 is present in the organum vasculosum of the lamina terminalis (OVLT), but not in the subfornical organ (SFO). Based on the QRT‐PCR and IHC results, we conclude that the benzamil‐blockable channel ASIC2 is present in the OVLT, a circumventricular organ that responds to osmotic stimuli. Although further studies are needed to assess a functional role of ASIC2 in osmoregulation, these data suggest that ASIC2 is present in osmosenstive structures in the LT, potentially enabling ASIC2 to modulate osmotically driven responses.