Sympathetic vasoconstriction in the rat anterior choroid is mediated by α1-adrenoceptors

Kawarai, Masahiro; Koss, Michael C.

doi:10.1016/s0014-2999(98)00790-0

Cited by 42 publications

(33 citation statements)

References 23 publications

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“…From in vivo studies it is known that sympathetic nerve stimulation causes vasoconstriction in the anterior choroid mediated mainly by the α " -adrenoceptor mechanism (Koss, 1994 ;Kawarai and Koss 1998). In the present study we have for the first time shown that the α " -adrenoceptors in the rabbit choroid are of the α "A -type.…”

Section: Discussionsupporting

confidence: 56%

“…Several studies on the effects of cervical sympathetic nerve stimulation on the vascular circulation of the eye have been performed (Bill, 1962 ;Alm and Bill, 1973). It has been suggested that the vasoconstriction in the anterior choroid brought about by stimulation of cervical sympathetic nerves is mediated by activation of α " -but not by α # -adrenoceptors (Koss and Gherezghiher, 1993 ;Kawarai and Koss, 1998). Adrenaline induced a vasoconstrictive effect mediated by postsynaptic α " -and α # -adrenoceptors, although the predominating effect was mediated by the α # -adrenoceptors (Koss, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Characterization of α1-Adrenoceptor Subtypes in the Eye

Wikberg-Matsson

Uhlén

Wikberg

2000

Experimental Eye Research

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Section: Discussionsupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Characterization of α1-Adrenoceptor Subtypes in the Eye

Wikberg-Matsson

Uhlén

Wikberg

2000

Experimental Eye Research

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“…31 Accordingly, stimulation of the sympathetic system has been shown to be associated with a pronounced reduction in blood flow in a variety of species. 2,[33][34][35] It has been hypothesized that the sympathetic nervous system plays a role in protecting the choroid against overperfusion during an increase in blood pressure. 36 Hence, our results would be compatible with the hypothesis that ChBF changes during isometric exercise are largely dependent on the stimulation of the sympathetic system.…”

Section: Discussionmentioning

confidence: 99%

“…This hypothesis is supported by results in several animal experiments, which clearly indicate a key role of this receptor subtype in the vasoconstrictor response in face of an increase in OPP. 34,35 During the elevation in IOP with the suction cup, it seems justified to assume that stimulation of the sympathetic and parasympathetic system is less pronounced than during isometric exercise, although experimental data are lacking. Accordingly, the larger capacity of the choroid to regulate during changes in blood pressure may also depend on pronounced changes in nervous input.…”

Section: Discussionmentioning

confidence: 99%

Regulation of Choroidal Blood Flow during Combined Changes in Intraocular Pressure and Arterial Blood Pressure

Polska¹,

Simader²,

Weigert³

et al. 2007

Invest. Ophthalmol. Vis. Sci.

167

153

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“…Our observations reporting changes in conjunctival/episcleral thickness are consistent with previous work, which found vasomotor changes in the anterior segment vasculature after administration of adrenergic agonists (Alm and Bill, 1973;Alm, 1977;Sugiyama et al, 1992;Kawarai andKoss, 1998 andKoss, 2002) and cholinergic…”

Section: Discussionsupporting

confidence: 93%

The Influence of the Autonomic Nervous System on the Human Choroid

Sander¹

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v AbstractThe impact of myopia is greater than just its optical consequences and in severe cases it can lead to a loss of vision. It is a highly prevalent eye disorder, with about one third of the population worldwide affected by this refractive error. Despite extensive research, the pathogenesis of myopia is still only partially understood. An improved knowledge of mechanisms underlying myopia is critical to developing new therapies to prevent myopia or to slow its progression.Although there is no fully effective and satisfactory myopia control treatment available, growing evidence has suggested that the choroid has a passive or active role in the regulation of eye growth and refractive error development. Numerous human and animal studies have shown that the retina can be moved forward or backward towards the image plane through changes in choroidal thickness, and these changes are likely to be associated in the longer term with eye growth and the development of refractive errors. As the choroid receives a rich innervation from the autonomic nervous system, many previous animal studies have utilized pharmacological agents and neurotoxins to elucidate the possible role of muscarinic signaling in the regulation of choroidal thickness, but only a few studies have investigated this issue in humans. An improved understanding of the mechanisms that control choroidal thickness may be important in developing new therapies for combating the development and progression of myopia.The research described in the thesis aimed to investigate the role of the autonomic nervous system in the control of choroidal thickness, axial length and the morphology In a series of experiments, we have confirmed that in humans under normal visual conditions, the parasympathetic nervous system is involved in the short-term regulation of subfoveal and parafoveal choroidal thickness, axial length and the morphology of the anterior sclera. The muscarinic blocker homatropine caused a significant subfoveal and parafoveal choroidal thickening, shortening of axial length, an enlargement of Schlemm's canal area and an increase in thickness of the conjunctival/episcleral complex. On the other hand, no notable changes in ocular parameters, except a decrease in the thickness of the conjunctival/episcleral tissues were found after instillation of the sympathomimetic drug phenylephrine.In an attempt to further improve our understanding of the myopigenic mechanisms influencing the thickness of the choroid in humans, we investigated the short-term influence of mixed interventions (positive and negative lens-imposed defocus / 2% homatropine) on choroidal thickness and axial length in emmetropic and myopic subjects. Homatropine prevented choroidal thinning in response to hyperopic defocus.This finding is consistent with the anti-myopia effects of muscarinic blockers and supports the potential importance of hyperopic defocus in the development of human myopia. By contrast, co-administration of homatropine with myopic defocus did not enhance the thicken...

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Sympathetic vasoconstriction in the rat anterior choroid is mediated by α1-adrenoceptors

Cited by 42 publications

References 23 publications

Characterization of α1-Adrenoceptor Subtypes in the Eye

Characterization of α1-Adrenoceptor Subtypes in the Eye

Regulation of Choroidal Blood Flow during Combined Changes in Intraocular Pressure and Arterial Blood Pressure

The Influence of the Autonomic Nervous System on the Human Choroid

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