Chrna6

Neuronal acetylcholine receptor subunit alpha-6

Spatial tier: RESTRICTED · Class: ION_CHANNEL · Top region: IF (Interfascicular nucleus raphe) · Positive regions: 18/554

50.4Discovery Score

44.2Targetability Score

CEvidence grade C

What this means: Chrna6: fine CCF profile is restricted toward IF (top regions: IF, VTA, IPDM, PN, SNc; 18 positive regions); direct spatial validation is still required.

Function in IF: evidence, prediction, innovation

Gene function

CHRNA6 encodes the alpha-6 subunit of neuronal nicotinic acetylcholine receptors, ligand-gated cation channels assembled as pentamers. Alpha-6 partners with beta-2 and beta-3 (often with alpha-4) to form high-affinity, rapidly desensitising receptors, and it is blocked with high selectivity by the cone-snail peptide alpha-conotoxin MII. Its expression in the brain is almost entirely restricted to catecholaminergic neurons, where it mediates nicotine-evoked dopamine release.

Region function

The interfascicular nucleus raphe is a midline midbrain nucleus wedged between the fasciculi retroflexi; it contains dopaminergic neurons continuous with the VTA together with serotonergic raphe cells and projects to medial prefrontal cortex, nucleus accumbens shell and interpeduncular nucleus.

Published in this region

inferred No region-specific literature found. Azam et al. 2002 showed alpha-6 mRNA within midbrain dopamine neurons across the VTA and substantia nigra, a population continuous with the interfascicular nucleus, and functional work on alpha-6 has concentrated on VTA and substantia nigra somata and striatal terminals - Collo et al. 2018 on nicotine-induced structural plasticity, Liu et al. 2013 and Gao et al. 2019 on ethanol sensitivity - without isolating the interfascicular subnucleus.

Predicted function

Prediction: interfascicular dopamine neurons project preferentially to medial prefrontal cortex and accumbens shell rather than to dorsal striatum, so alpha-6 here is predicted to mediate a cortically biased arm of nicotine reinforcement that is pharmacologically separable from the classical VTA-to-accumbens-core pathway. Alpha-conotoxin MII infused into IF, or IF-restricted Chrna6 knockdown, is predicted to reduce nicotine-evoked prefrontal dopamine release and selectively decrease nicotine conditioned place preference at low doses while sparing high-dose aversion; conversely the gain-of-function Chrna6 L9S mouse should show exaggerated IF activation and hypersensitivity to nicotine reward.

Innovation

★★★★☆ 4/5 Alpha-6 nicotinic receptors are heavily studied in VTA and striatum but nobody has separated the interfascicular population, even though alpha-conotoxin MII and dedicated mouse lines make the experiment straightforward.

Tools

Chrna6 knockout mice, the Chrna6 L9S gain-of-function line and Chrna6-eGFP (GENSAT) reporter; alpha-conotoxin MII and PIA, bPiDI and the alpha6beta2-selective antagonists; nicotine and varenicline; Dat-Cre and Th-Cre for cell-type restriction; GRAB-DA photometry in prefrontal cortex.

References

Direct evidence located at the region

Chrna6 Allen ISH at the CCF centroid of IF

Allen ISH experiment 75551461, section image 75488379 (section 194): the section that contains the CCF centroid of Interfascicular nucleus raphe according to the Allen image-to-atlas alignment (reference_to_image), with a 2 mm window around that point. Left: whole section, red box = window. Middle: ISH signal. Right: Allen's expression-mask view of the same window. open this image in the Allen viewer

Allen ISH experiment 75651213, section image 75589023 (section 198): the section that contains the CCF centroid of Interfascicular nucleus raphe according to the Allen image-to-atlas alignment (reference_to_image), with a 2 mm window around that point. Left: whole section, red box = window. Middle: ISH signal. Right: Allen's expression-mask view of the same window. open this image in the Allen viewer

Look it up yourself: Allen Mouse Brain ISH for Chrna6 Allen reference atlas: IF (structure 12)ABC Atlas MERFISH viewer(in the ABC Atlas choose dataset MERFISH-C57BL6J-638850-CCF, colour cells by gene "Chrna6" or by parcellation_substructure "IF")All genes confined to IF + 3-D brain

Direct spatial evidence

IF MERFISH region locator — Real single-cell MERFISH coordinates for the IF (Interfascicular nucleus raphe) section -- our own ground-truth data, showing exactly where this region sits, independent of whether the Allen ISH section below is easy to read.

Regional expression figure

Predicted WMB × fine-CCF profile; not direct full-transcriptome spatial measurement.

Spatial profile

2.62

VTA

2.6

IPDM

2.37

1.82

SNc

1.75

CLI

1.66

1.13

IPA

1.11

IPR

1.07

0.858

IPDL

0.777

SUM

0.768

SLC

0.753

SCsg

0.656

0.595

SCzo

0.594

IPC

0.589

0.575

IPI

0.397

0.384

Evidence and specificity

Evidence status: PREDICTED_FINE
Direct sources: None; predicted localization only
Exclusive threshold: 12 positive regions out of 554
Spatial specificity: 0.425
Top-region fraction: 0.090
Filter status: PASS

Interpretation limits

Cell-type-to-region projection is imputed expression, not direct spatial measurement.
Adult reference atlases do not establish stability across age, sex, strain, state, or disease.
Transcript abundance does not guarantee protein abundance or genetic-tool performance.