[The role of sympathetic cervical ganglion in the effect of clonidine for lowering intraocular pressure].
The contribution of sympathetic cervical ganglion to the mechanism of action of clonidine for lowering intraocular pressure (IOP) was investigated. Pigmented rabbits were used. The animals were divided into 3 groups: normal control group (group 1), animals in which the bilateral cervical sympathetic trunks had been amputated presynaptically (group 2), animals in which the superior cervical ganglion (SCG) had been bilaterally dissected (group 3). Changes in IOP were measured after topical application of clonidine unilaterally. In group 1, IOP was significantly decreased in eye treated by clonidine and contralateral eyes compared to pretreatment values. Decrease of IOP in the contralateral eye was greater than that in the treated eye. In group 2, IOP was decreased in the contralateral eye but increased in the eye treated by clonidine. Pretreatment of yohimbine administered orally antagonized the ocular hypotensive effect of clonidine in a dose-related manner. In group 3, where SCGs were dissected, no changes in IOP were observed in both eyes by unilateral administration of clonidine. These results suggested that the bilateral ocular hypotensive effect of clonidine administered unilaterally is in part due to direct action on the SCG and that the alpha 2 receptor in the SCG plays some role in the regulation of IOP.
Iizuka
T
T
Department of Ophthalmology, School of Medicine, Showa University, Shinagawa-ku, Japan.
Koike
N
N
Moriwaki
Y
Y
Ueda
T
T
Koide
R
R
Inatomi
M
M
Fukado
Y
Y
Uchida
E
E
Kobayashi
S
S
Oguchi
K
K
D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D003864:Depression, Chemical; D005728:Ganglia, Sympathetic / Q000502:physiology*; D015171:Ganglionectomy / Q000379:methods; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D011817:Rabbits
D003000:Clonidine