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Whole-Retina Reduced Electrophysiological Activity in Mice Bearing Retina-Specific Deletion of Vesicular Acetylcholine Transporter.

Bedore J, Martyn AC, Li AK, Dolinar EA, McDonald IS, Coupland SG, Prado VF, Prado MA, Hill KA - PLoS ONE (2015)

Bottom Line: One of the unanswered questions is how acetylcholine contributes to the functional capacity of mature retinal circuits.Reduced a-wave amplitude was proportional to the reduction in b-wave amplitude and not associated with altered a-wave 10%-90% rise time or inner and outer segment thicknesses.Reduced amplitude across the electroretinogram wave form does not suggest dysfunction in specific retinal cell types and could reflect underlying changes in the retinal and/or extraretinal microenvironment.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, The University of Western Ontario, London, Ontario, Canada N6A 5B7.

ABSTRACT

Background: Despite rigorous characterization of the role of acetylcholine in retinal development, long-term effects of its absence as a neurotransmitter are unknown. One of the unanswered questions is how acetylcholine contributes to the functional capacity of mature retinal circuits. The current study investigates the effects of disrupting cholinergic signalling in mice, through deletion of vesicular acetylcholine transporter (VAChT) in the developing retina, pigmented epithelium, optic nerve and optic stalk, on electrophysiology and structure of the mature retina.

Methods & results: A combination of electroretinography, optical coherence tomography imaging and histological evaluation assessed retinal integrity in mice bearing retina- targeted (embryonic day 12.5) deletion of VAChT (VAChTSix3-Cre-flox/flox) and littermate controls at 5 and 12 months of age. VAChTSix3-Cre-flox/flox mice did not show any gross changes in nuclear layer cellularity or synaptic layer thickness. However, VAChTSix3-Cre-flox/flox mice showed reduced electrophysiological response of the retina to light stimulus under scotopic conditions at 5 and 12 months of age, including reduced a-wave, b-wave, and oscillatory potential (OP) amplitudes and decreased OP peak power and total energy. Reduced a-wave amplitude was proportional to the reduction in b-wave amplitude and not associated with altered a-wave 10%-90% rise time or inner and outer segment thicknesses.

Significance: This study used a novel genetic model in the first examination of function and structure of the mature mouse retina with disruption of cholinergic signalling. Reduced amplitude across the electroretinogram wave form does not suggest dysfunction in specific retinal cell types and could reflect underlying changes in the retinal and/or extraretinal microenvironment. Our findings suggest that release of acetylcholine by VAChT is essential for the normal electrophysiological response of the mature mouse retina.

No MeSH data available.


Related in: MedlinePlus

Assessment of oscillatory potential (OP) maximum power, total energy and frequency.A fast Fourier transformation was applied to OP data from the four highest stimulus strengths (0.25–25 cd˖s/m2) filtered with a bandpass of 65-300Hz to assess OP profiles in the frequency domain. Peak power is decreased in VAChTSix3-Cre-flox/flox retinas (open circles) relative to littermate controls (closed squares) at (A) 5 (n = 7 VAChTSix3-Cre-flox/flox and n = 12 littermate control) and (B) 12 months of age (n = 5 VAChTSix3-Cre-flox/flox and n = 5 littermate control). Total OP energy is also decreased in VAChTSix3-Cre-flox/flox retinas relative to littermate controls at both (C) 5 and (D) 12 months of age. Average OP frequency does not differ between VAChTSix3-Cre-flox/flox and littermate control mice at either (E) 5 or (F) 12 months of age. Values represent the mean ± SEM. δ, P < 0.05; γ, P < 0.01, β, P < 0.001, α, P < 0.0001 versus control mice.
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pone.0133989.g007: Assessment of oscillatory potential (OP) maximum power, total energy and frequency.A fast Fourier transformation was applied to OP data from the four highest stimulus strengths (0.25–25 cd˖s/m2) filtered with a bandpass of 65-300Hz to assess OP profiles in the frequency domain. Peak power is decreased in VAChTSix3-Cre-flox/flox retinas (open circles) relative to littermate controls (closed squares) at (A) 5 (n = 7 VAChTSix3-Cre-flox/flox and n = 12 littermate control) and (B) 12 months of age (n = 5 VAChTSix3-Cre-flox/flox and n = 5 littermate control). Total OP energy is also decreased in VAChTSix3-Cre-flox/flox retinas relative to littermate controls at both (C) 5 and (D) 12 months of age. Average OP frequency does not differ between VAChTSix3-Cre-flox/flox and littermate control mice at either (E) 5 or (F) 12 months of age. Values represent the mean ± SEM. δ, P < 0.05; γ, P < 0.01, β, P < 0.001, α, P < 0.0001 versus control mice.

Mentions: VAChTSix3-Cre-flox/flox mice show changes in OP parameters that are apparent in both the time and frequency domain (Fig 6). The maximum power of the OPs (Fig 7A and 7B; P < 0.0001) as well as the total energy of the OPs (Fig 7C and 7D; P < 0.0001) are significantly lower in VAChTSix3-Cre-flox/flox than littermate control mice at both ages examined (Fig 7A and 7B; P < 0.0001). There are no changes in the dominant frequencies of the OPs between VAChTSix3-Cre-flox/flox mice and littermate controls at either age (Fig 7E and 7F).


Whole-Retina Reduced Electrophysiological Activity in Mice Bearing Retina-Specific Deletion of Vesicular Acetylcholine Transporter.

Bedore J, Martyn AC, Li AK, Dolinar EA, McDonald IS, Coupland SG, Prado VF, Prado MA, Hill KA - PLoS ONE (2015)

Assessment of oscillatory potential (OP) maximum power, total energy and frequency.A fast Fourier transformation was applied to OP data from the four highest stimulus strengths (0.25–25 cd˖s/m2) filtered with a bandpass of 65-300Hz to assess OP profiles in the frequency domain. Peak power is decreased in VAChTSix3-Cre-flox/flox retinas (open circles) relative to littermate controls (closed squares) at (A) 5 (n = 7 VAChTSix3-Cre-flox/flox and n = 12 littermate control) and (B) 12 months of age (n = 5 VAChTSix3-Cre-flox/flox and n = 5 littermate control). Total OP energy is also decreased in VAChTSix3-Cre-flox/flox retinas relative to littermate controls at both (C) 5 and (D) 12 months of age. Average OP frequency does not differ between VAChTSix3-Cre-flox/flox and littermate control mice at either (E) 5 or (F) 12 months of age. Values represent the mean ± SEM. δ, P < 0.05; γ, P < 0.01, β, P < 0.001, α, P < 0.0001 versus control mice.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520552&req=5

pone.0133989.g007: Assessment of oscillatory potential (OP) maximum power, total energy and frequency.A fast Fourier transformation was applied to OP data from the four highest stimulus strengths (0.25–25 cd˖s/m2) filtered with a bandpass of 65-300Hz to assess OP profiles in the frequency domain. Peak power is decreased in VAChTSix3-Cre-flox/flox retinas (open circles) relative to littermate controls (closed squares) at (A) 5 (n = 7 VAChTSix3-Cre-flox/flox and n = 12 littermate control) and (B) 12 months of age (n = 5 VAChTSix3-Cre-flox/flox and n = 5 littermate control). Total OP energy is also decreased in VAChTSix3-Cre-flox/flox retinas relative to littermate controls at both (C) 5 and (D) 12 months of age. Average OP frequency does not differ between VAChTSix3-Cre-flox/flox and littermate control mice at either (E) 5 or (F) 12 months of age. Values represent the mean ± SEM. δ, P < 0.05; γ, P < 0.01, β, P < 0.001, α, P < 0.0001 versus control mice.
Mentions: VAChTSix3-Cre-flox/flox mice show changes in OP parameters that are apparent in both the time and frequency domain (Fig 6). The maximum power of the OPs (Fig 7A and 7B; P < 0.0001) as well as the total energy of the OPs (Fig 7C and 7D; P < 0.0001) are significantly lower in VAChTSix3-Cre-flox/flox than littermate control mice at both ages examined (Fig 7A and 7B; P < 0.0001). There are no changes in the dominant frequencies of the OPs between VAChTSix3-Cre-flox/flox mice and littermate controls at either age (Fig 7E and 7F).

Bottom Line: One of the unanswered questions is how acetylcholine contributes to the functional capacity of mature retinal circuits.Reduced a-wave amplitude was proportional to the reduction in b-wave amplitude and not associated with altered a-wave 10%-90% rise time or inner and outer segment thicknesses.Reduced amplitude across the electroretinogram wave form does not suggest dysfunction in specific retinal cell types and could reflect underlying changes in the retinal and/or extraretinal microenvironment.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, The University of Western Ontario, London, Ontario, Canada N6A 5B7.

ABSTRACT

Background: Despite rigorous characterization of the role of acetylcholine in retinal development, long-term effects of its absence as a neurotransmitter are unknown. One of the unanswered questions is how acetylcholine contributes to the functional capacity of mature retinal circuits. The current study investigates the effects of disrupting cholinergic signalling in mice, through deletion of vesicular acetylcholine transporter (VAChT) in the developing retina, pigmented epithelium, optic nerve and optic stalk, on electrophysiology and structure of the mature retina.

Methods & results: A combination of electroretinography, optical coherence tomography imaging and histological evaluation assessed retinal integrity in mice bearing retina- targeted (embryonic day 12.5) deletion of VAChT (VAChTSix3-Cre-flox/flox) and littermate controls at 5 and 12 months of age. VAChTSix3-Cre-flox/flox mice did not show any gross changes in nuclear layer cellularity or synaptic layer thickness. However, VAChTSix3-Cre-flox/flox mice showed reduced electrophysiological response of the retina to light stimulus under scotopic conditions at 5 and 12 months of age, including reduced a-wave, b-wave, and oscillatory potential (OP) amplitudes and decreased OP peak power and total energy. Reduced a-wave amplitude was proportional to the reduction in b-wave amplitude and not associated with altered a-wave 10%-90% rise time or inner and outer segment thicknesses.

Significance: This study used a novel genetic model in the first examination of function and structure of the mature mouse retina with disruption of cholinergic signalling. Reduced amplitude across the electroretinogram wave form does not suggest dysfunction in specific retinal cell types and could reflect underlying changes in the retinal and/or extraretinal microenvironment. Our findings suggest that release of acetylcholine by VAChT is essential for the normal electrophysiological response of the mature mouse retina.

No MeSH data available.


Related in: MedlinePlus