The effects of insulin on the electroretinogram of bovine retina<i>in vitro</i>

Gosbell, Andrew; Favilla, Ian; Jablonski, Paula

doi:10.3109/02713689608995145

Cited by 17 publications

(10 citation statements)

References 9 publications

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“…Although no receptors have been identified so far, CART appeared to inhibit voltage-dependent intracellular Ca 2ϩ signaling and attenuated cocaine enhancement of depolarization-induced Ca 2ϩ influx in rat hippocampal neurons (28). Application of insulin to the in vitro bovine retina preparation decreased the amplitudes of the a-and b-waves of the electroretinogram (29). Insulin receptors are widely expressed in the retina (30), and administration of this hormone modified the permeability of voltage-gated K ϩ and Ca 2ϩ channels through receptor-mediated tyrosine phosphorylation, thus modulating the activity of photoreceptors and Müller cells.…”

Section: Discussionmentioning

confidence: 98%

Gene discovery in genetically labeled single dopaminergic neurons of the retina

Gustincich

Contini

Gariboldi

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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In the retina, dopamine plays a central role in neural adaptation to light. Progress in the study of dopaminergic amacrine (DA) cells has been limited because they are very few (450 in each mouse retina, 0.005% of retinal neurons). Here, we applied transgenic technology, single-cell global mRNA amplification, and cDNA microarray screening to identify transcripts present in DA cells. To profile gene expression in single neurons, we developed a method (SMART7) that combines a PCR-based initital step (switching mechanism at the 5 end of the RNA transcript or SMART) with T7 RNA polymerase amplification. Single-cell targets were synthesized from genetically labeled DA cells to screen the RIKEN 19k mouse cDNA microarrays. Seven hundred ninety-five transcripts were identified in DA cells at a high level of confidence, and expression of the most interesting genes was confirmed by immunocytochemistry. Twenty-one previously undescribed proteins were found in DA cells, including a chloride channel, receptors and other membrane glycoproteins, kinases, transcription factors, and secreted neuroactive molecules. Thirty-eight percent of transcripts were ESTs or coding for hypothetical proteins, suggesting that a large portion of the DA cell proteome is still uncharacterized. Because cryptochrome-1 mRNA was found in DA cells, immunocytochemistry was extended to other components of the circadian clock machinery. This analysis showed that DA cells contain the most common clock-related proteins.

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Section: Discussionmentioning

confidence: 98%

Gene discovery in genetically labeled single dopaminergic neurons of the retina

Gustincich

Contini

Gariboldi

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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“…The decrease in tonic glutamate release from photoreceptors that would presumably accompany decreased activation of I Ca might also minimize the potential for excitotoxic damage to post-receptoral neurons. In addition to possible neuroprotective benefits, the inhibitory effects of insulin on the ERG bwave [9] and rod Ca 2+ channel (described in this study) indicate that insulin could play a neuromodulatory role in regulating synaptic transmission from rods to second-order neurons. Finally, the present results suggest that alterations in retinal insulin levels or sensitivity to insulin, e.g., during diabetes, may affect photoreceptor cell survival and neurotransmission at the first synapse in the retina.…”

Section: Discussionmentioning

confidence: 99%

“…InsRs are located on both the inner and outer segments of vertebrate photoreceptors [8] and insulin has been shown to produce a dose-dependent decrease in the a-and b-waves of the electroretinogram (ERG) [9]. The ERG b-wave reflects the activity of inputs from photoreceptors onto ON depolarizing bipolar cells [10].…”

Section: Introductionmentioning

confidence: 99%

Insulin inhibits voltage-dependent calcium influx into rod photoreceptors

2001

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Insulin inhibits the ERG b-wave and modulates L-type calcium currents (I Ca ) in various preparations. We therefore examined insulin's effects on I Ca and depolarization-evoked [Ca 2+ ] i increases in rod photoreceptors. Insulin inhibited I Ca and caused a dose-dependent reduction in the depolarizationevoked Ca 2+ influx with an EC 50 of 2.1 nM. Tyrosine kinase inhibitors, lavendustin A (100 nM) and genistein (10 μM), prevented insulin from reducing the depolarization-evoked Ca 2+ increase in rods. Their less active analogues, lavendustin B and daidzein, had similar effects. An insulin receptorspecific tyrosine kinase inhibitor, HNMPA-(AM) 3 (50 μM), prevented insulin (30 nM) from reducing the depolarization-evoked Ca 2+ increase in rods. The results suggest that insulin inhibits Ca 2+ influx through voltage-dependent I Ca in rod photoreceptors via tyrosine kinase activity.

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“…In the rat retina, Johnson et al (2001) found that SRIF reduced Ca 2+ influx into rod bipolar terminals. (Gosbell et al, 1996) and L-type Ca 2+ channels in rod photoreceptors (Stella et al, 2001). The potency of insulin's actions (IC50 = 2 nM) and the effectiveness of an insulin receptor-specific tyrosine kinase inhibitor suggest that receptors for insulin, and not insulin-like growth factor, are responsible for these effects (Stella et al, 2001).…”

Section: Cannabinoids-cannabinoidsmentioning

confidence: 99%

Synaptic transmission at retinal ribbon synapses

Heidelberger

Thoreson

Witkovsky

2005

Progress in Retinal and Eye Research

208

231

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The molecular organization of ribbon synapses in photoreceptors and ON bipolar cells is reviewed in relation to the process of neurotransmitter release. The interactions between ribbon synapseassociated proteins, synaptic vesicle fusion machinery and the voltage-gated calcium channels that gate transmitter release at ribbon synapses are discussed in relation to the process of synaptic vesicle exocytosis. We describe structural and mechanistic specializations that permit the ON bipolar cell to release transmitter at a much higher rate than the photoreceptor does, under in vivo conditions. We also consider the modulation of exocytosis at photoreceptor synapses, with an emphasis on the regulation of calcium channels.

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The effects of insulin on the electroretinogram of bovine retinain vitro

Cited by 17 publications

References 9 publications

Gene discovery in genetically labeled single dopaminergic neurons of the retina

Gene discovery in genetically labeled single dopaminergic neurons of the retina

Insulin inhibits voltage-dependent calcium influx into rod photoreceptors

Synaptic transmission at retinal ribbon synapses

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