The Activity of the Pupilloconstrictory Centers

Nisida, Isamu; Okada, Hiromasa

doi:10.2170/jjphysiol.10.64

Cited by 24 publications

(1 citation statement)

References 5 publications

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“…Furthermore, the mydriasis to either drug was greater evoked by brief (200 ms) light pulses [30]. Furthermore, electrophysiological studies indicate that a phasic light in the light than in the dark, presumably due to the curtailment of the mydriasis in the dark by the operation stimulus has an inhibitory effect on on-going sympathetic activity recorded in the dark [ 31]. of a ceiling effect [ 19].…”

Section: Discussion Salivationmentioning

confidence: 99%

Comparison of the effects of clonidine on tyramine‐ and methoxamine‐evoked mydriasis in man

Bitsios

Langley

Szabadi

et al. 1996

Brit J Clinical Pharma

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1 It has been reported previously that clonidine can potentiate tyramine‐evoked mydriasis on the pain‐free side of cluster headache patients. We examined whether a single oral dose of clonidine (200 μg) can also potentiate tyramine‐evoked mydriasis in healthy subjects, using mydriasis to methoxamine, a directly acting sympathomimetic amine, as a control. 2 Eight healthy male volunteers participated in four weekly sessions. In the first two sessions (Experiment 1) the effect of clonidine or placebo on the mydriasis to tyramine hydrochloride eyedrops (75 mm; 2×10 μl), and in the last two sessions (Experiment 2) the effect of clonidine or placebo on the mydriasis to methoxamine hydrochloride eyedrops (20 mm; 2×10 μl) was examined. In both experiments subjects were allocated to drugs and sessions according to a double‐blind balanced design. In both experiments, pupil diameter of both the treated and the untreated eyes was recorded in standard ambient light and in the dark, before, and 2 h after clonidine/placebo, via binocular infrared television pupillometry. Salivation (dental roll technique), systolic and diastolic blood pressure (sitting), heart rate, and self‐ratings of mood and feelings (visual analogue scales), were also measured before, and 2 h after the ingestion of clonidine or placebo. 3 Both tyramine and methoxamine produced a significant mydriasis, which was more prominent in the light condition (change in resting pupil size; mm±s.e.mean: tyramine/light 1.05±0.28; tyramine/dark: 0.73±0.15; methoxamine/light: 1.65±0.28; methoxamine/dark: 0.85±0.15). Clonidine produced a significant miosis in the untreated eye which was more prominent in the light condition (change in resting pupil size; mm±s.e.mean: Experiment 1, light: −1.34±0.19; Experiment 1, dark: −0.46±0.1; Experiment 2, light −0.97±0.18; Experiment 2, dark: −0.29±0.17). Clonidine had no significant effect on either tyramine‐ or methoxamine‐evoked mydriasis. 4 In agreement with previous reports, clonidine significantly reduced salivation (g, mean±s.e.mean; Experiment 1: −0.84±0.22; Experiment 2: −0.55±0.11), systolic blood pressure (mm Hg; Experiment 1: −17.5±3.76; Experiment 2: −23.38±4.67), diastolic blood pressure (mm Hg; Experiment 2: −12.38±2.05), alertness (mm; Experiment 2: −24.19±5.40), and anxiety (mm; Experiment 1: −13.82±4.60), indicating the presence of pharmacodynamically effective tissue levels of the drug. 5 These results show that a single oral dose (200 μg) of clonidine causes significant miosis in human subjects, and fails to potentiate tyramine‐evoked mydriasis. This indicates that the pupil on the asymptomatic side of cluster headache patients is affected differently from the pupils of healthy volunteers by tyramine and/or clonidine.

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Section: Discussion Salivationmentioning

confidence: 99%

Comparison of the effects of clonidine on tyramine‐ and methoxamine‐evoked mydriasis in man

Bitsios

Langley

Szabadi

et al. 1996

Brit J Clinical Pharma

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The Neural Control of Pupilloconstrictor Activity

Sillito¹,

Zbrożyna²

1973

Symposion Der Deutschen Ophthalmologischen Gesellschaft

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Identification of the teleost Edinger-Westphal nucleus by retrograde horseradish peroxidase labeling and by electrophysiological criteria

Wathey

1988

J. Comp. Physiol.

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A homolog of the Edinger-Westphal nucleus of other vertebrates is described in two species of serranid basses of the genus Paralabrax, a group possessing a wide range of ocular accommodation but lacking a pupillary reflex to light. The nucleus was found by retrograde labeling from the ciliary ganglion and lies dorsolateral to the ipsilateral oculomotor nucleus. The nucleus consists of 60 to 100 neurons with an average soma diameter of about 20 microns in animals weighing 70 to 150 g. Electrophysiological experiments support the identification. Microstimulation of the nucleus evokes contraction of the ipsilateral lens retractor muscle and slight constriction of the caudal ipsilateral iris. Multi- and single-unit recordings in the nucleus reveal spontaneous firing (about 30 spikes/s in single units), the rate of which decreases during visually-evoked lens retractor relaxations (accommodation to near stimuli). Recordings of muscle fiber activity in the lens retractor show essentially the same behavior, which suggests that the ciliary ganglion and neuromuscular junctions simply relay impulses with little if any synaptic integration. The existence of a discrete Edinger-Westphal nucleus devoted largely to accommodation makes Paralabrax a good model system for the further tracing of central accommodation control pathways.

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The Activity of the Pupilloconstrictory Centers

Cited by 24 publications

References 5 publications

Comparison of the effects of clonidine on tyramine‐ and methoxamine‐evoked mydriasis in man

Comparison of the effects of clonidine on tyramine‐ and methoxamine‐evoked mydriasis in man

The Neural Control of Pupilloconstrictor Activity

Identification of the teleost Edinger-Westphal nucleus by retrograde horseradish peroxidase labeling and by electrophysiological criteria

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