Human ganglion cells express the alpha-2 adrenergic receptor: relevance to neuroprotection

Kalapesi, Freny B

doi:10.1136/bjo.2004.053025

Cited by 58 publications

(40 citation statements)

References 31 publications

(25 reference statements)

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“…43 In addition to the IOP-lowering potential, adrenergic agonists seem to have neuroprotective properties and alpha-2 receptors have been found to be present in RGCs. 46 In a rat model where transient ischemia was induced, brimonidine significantly reduced RGC loss. 47 In another study also carried out in rats, administration of brimonidine before inducing ischemia not only decreased RGC death but also sustained retrograde axonal transport.…”

Section: Topical Therapiesmentioning

confidence: 98%

Pharmacotherapy of Glaucoma

Schmidl

Schmetterer²,

Garhöfer³

et al. 2015

Journal of Ocular Pharmacology and Therapeutics

132

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Glaucoma is a group of diseases involving the optic nerve and associated structures, which is characterized by progressive visual field loss and typical changes of the optic nerve head (ONH). The only known treatment of the disease is reduction of intraocular pressure (IOP), which has been shown to reduce glaucoma progression in a variety of large-scale clinical trials. Nowadays, a relatively wide array of topical antiglaucoma drugs is available, including prostaglandin analogues, carbonic anhydrase inhibitors, beta-receptor antagonists, adrenergic agonists, and parasympathomimetics. In clinical routine, this allows for individualized treatment taking risk factors, efficacy, and safety into account. A major challenge is related to adherence to therapy. Sustained release devices may help minimize this problem but are not yet available for clinical routine use. Another hope arises from non-IOP-related treatment concepts. In recent years, much knowledge has been gained regarding the molecular mechanisms that underlie the disease process in glaucoma. This also strengthens the hope that glaucoma therapy beyond IOP lowering will become available. Implementing this concept with clinical trials remains, however, a challenge.

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Section: Topical Therapiesmentioning

confidence: 98%

Pharmacotherapy of Glaucoma

Schmidl

Schmetterer²,

Garhöfer³

et al. 2015

Journal of Ocular Pharmacology and Therapeutics

132

View full text Add to dashboard Cite

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“…The expression of multiple adrenergic receptor subtypes in taste buds parallels findings in other sensory systems such as the retina (Dong et al , 2007, Kalapesi et al , 2005, Zarbin et al , 1986), the organ of Corti (Fauser et al , 2004, Khan et al , 2007), and the olfactory bulb (Doucette et al , 2007, Ennis et al , 2007, Nai et al , 2009). In each, the expression of both alpha and beta receptors across peripheral receptor cells or output neurons appear to share a common general conclusion: adrenergic receptors play a modulatory rather than primary functional role in sensory stimulation.…”

Section: Discussionmentioning

confidence: 54%

Characterization of the expression pattern of adrenergic receptors in rat taste buds

et al. 2010

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Taste buds signal the presence of chemical stimuli in the oral cavity to the central nervous system using both early transduction mechanisms, which allow single cells to be depolarized via receptor-mediated signaling pathways, and late transduction mechanisms, which involve extensive cell-to-cell communication among the cells in the bud. The latter mechanisms, which involve a large number of neurotransmitters and neuropeptides, are less well understood. Among neurotransmitters, multiple lines of evidence suggest that norepinephrine plays a yet unknown role in the taste bud. This study investigated the expression pattern of adrenergic receptors in the rat posterior taste bud. Expression of α1A, α1B, α1D, α2A, α2B, α2C, β1, and the β2 adrenoceptor subtypes was observed in taste buds using RT-PCR and immunocytochemical techniques. Taste buds also expressed the biosynthetic enzyme for norepinephrine, dopamine β-hydroxylase (DβH), as well as the norepinephrine transporter. Further, expression of the epinephrine synthetic enzyme, phenylethanolamine N-methyltransferase (PNMT), was observed suggesting a possible role for this transmitter in the bud. Phenotyping adrenoceptor expression patterns with double labeling experiments to gustducin, synaptosomal-associated protein 25 (SNAP-25), and neural cell adhesion molecule (NCAM) suggests they are prominently expressed in subsets of cells known to express taste receptor molecules but segregated from cells known to have synapses with the afferent nerve fiber. Alpha and beta adrenoceptors co-express with one another in unique patterns as observed with immunocytochemistry and single cell RT-PCR. These data suggest that single cells express multiple adrenergic receptors and that adrenergic signaling may be particularly important in bitter, sweet, and umami taste qualities. In summary, adrenergic signaling in the taste bud occurs through complex pathways that include presynaptic and postsynaptic receptors and likely play modulatory roles in processing of gustatory information similar to other peripheral sensory systems such as the retina, cochlea, and olfactory bulb.

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“…Alpha-2 adrenergic receptor (A2R) is systemically distributed and its subtypes are pharmacologically defined as 2A/D, 2B and 2C [15,16]. It was revealed that the a-2A receptor is expressed in the GCL and inner nuclear layer of the mammal retina, possibly involving the regenerative effect of A2A directly on the RGCs [17]. The retinal localization of other subtypes of A2R, however, has not yet been well investigated.…”

Section: Discussionmentioning

confidence: 99%

Xylazine promotes axonal regeneration in the crushed optic nerve of adult rats

Kurimoto

Ishii²,

Tagami³

et al. 2006

NeuroReport

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Xylazine, an alpha-2 adrenergic agonist, activates the endogenous trophic factors and neuronal survival signaling. Here, we tested the regenerative effect of xylazine on damaged optic nerve axons in adult rats. After optic nerve crush, xylazine was intraperitoneally injected into three groups of rats: a single administration immediately after the crush, intermittent administration, and daily administration. On day 14, the regenerated axons were quantitatively evaluated by anterograde labeling. Everyday administration but neither single nor intermittent administration markedly increased the number of labeled axons beyond the crush site, with upregulation of growth-associated protein-43 in the ganglion cell layer and the regenerated axons. It was concluded that xylazine promotes axonal regeneration in damaged optic nerves of adult rats.

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Human ganglion cells express the alpha-2 adrenergic receptor: relevance to neuroprotection

Cited by 58 publications

References 31 publications

Pharmacotherapy of Glaucoma

Pharmacotherapy of Glaucoma

Characterization of the expression pattern of adrenergic receptors in rat taste buds

Xylazine promotes axonal regeneration in the crushed optic nerve of adult rats

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