The expression of nicotinic receptor alpha7 during cochlear development

Abstract

Nicotinic acetylcholine receptor alpha7 expression was examined in the developing and adult auditory system using mice that were modified through homologous recombination to coexpress either GFP (alpha7GFP) or Cre (alpha7Cre), respectively. The expression of alpha7GFP is first detected at embryonic (E) day E13.5 in cells of the spiral prominence. By E14.5, sensory regions including the putative outer hair cells and Deiters' cells express alpha7GFP as do solitary efferent fibers. This pattern diminishes after E16.5 in a basal to apex progression, as Hensen's cells and cells of the spiral ligament acquire alpha7GFP expression. At birth and thereafter alpha7GFP also identifies a subset of spiral ganglion cells whose processes terminate on inner hair cells. Efferent fibers identified by peripherin or calcitonin gene-related protein do not coexpress alpha7GFP. In addition to cochlear structures, there is strong expression of alpha7GFP by cells of the central auditory pathways including the ventral posterior cochlear nucleus, lateral lemniscus, central inferior colliculus, and the medial geniculate nucleus. Our findings suggest that alpha7 expression by both neuronal and non-neuronal cells has the potential to impact multiple auditory functions through mechanisms that are not traditionally attributed to this receptor.

Nicotinic Receptor Alpha7 Expression during Mouse Adrenal Gland Development

“…This is compatible with the participation by α7 in this basic sympathetic physiological function, as has been reported by others [8], [12]. Finally, in other tissues α7 G expression is detected in peripherin labeled afferents [29], [30], but this was not observed in the adrenal gland (not shown).…”

“…As in other organs, the expression of α7 G exhibits significant modifications throughout development [28]–[30]. The expression of α7 is present in cells that populate the adrenal gland at E12.5, very shortly after migration of the adrenal anlagen to its location adjacent to the kidney [36].…”

Nicotinic Receptor Alpha7 Expression Identifies a Novel Hematopoietic Progenitor Lineage

“…Thus the α7 lin+ cells and the α7 KO both exhibit a more pro-inflammatory phenotype, but possibly through the apparent modulation of different cytokines. This result could reflect the complexities of α7 functional pleiotropy that are being revealed for the role this receptor has in directing a variety of developmental processes whose outcome may not be predicted by the functional role this receptor plays in the adult [18]–[20]. First, α7 expression exhibits onset at embryonic day 9 whereupon the pattern expands dramatically thereafter to include multiple tissues and cell types [18], [19].…”

“…Thus, there has been a challenge to clearly identify the cells that express α7 and then determine their relative response when exposed to ligand (e.g., nicotine). Toward resolving this limitation we employed homologous recombination to introduce an IRES-Cre bi-cistronic gene cassette after the 3′ end of the mouse α7 gene ( Chrna7 ) [18]–[20]. Upon crossing these mice with females harboring the conditional reporter; Rosa26-loxP (yellow fluorescent protein, YFP) [21]–[23], offspring are referred to as α7 Cre:YFP [18].…”

Desde la corteza auditiva a la cóclea: Progresos en el sistema eferente auditivo

“…Posteriormente, la presencia de ACh en el haz OCL fue descrita en otros modelos animales como el conejillo de indias (Cavia porcellus) 21 y confirmada a través de diferentes técnicas histoquímicas utilizando microscopía electrónica y anticuerpos monoclonales contra colina-acetiltranferasa 22,23 . La ACh actúa sobre receptores nicotínicos del tipo a7 (Figura 2) en el sistema OCL, siendo estos expresados desde la etapa embrionaria hasta la vida adulta 24 .…”