RT Journal Article
SR Electronic
T1 Evidence for the presence of serotonergic nerves and receptors in the iris-ciliary body complex of the rabbit
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 3713
OP 3721
DO 10.1523/JNEUROSCI.08-10-03713.1988
VO 8
IS 10
A1 AB Tobin
A1 W Unger
A1 NN Osborne
YR 1988
UL http://www.jneurosci.org/content/8/10/3713.abstract
AB The rabbit iris-ciliary body contains 78 +/- 6 ng/gm serotonin (5-HT) while the amine content in the aqueous humor is less than 0.01 ng/100 microliter. The low levels of endogenous 5-HT in the iris-ciliary body could not be directly detected by immunocytochemistry. However, pretreatment in vivo and in vitro with L-tryptophan and pargyline resulted in the localization of a sparse population of 5-HT fibers. These fibers could not be studied by exposing the tissue to exogenous 5- HT since the amine was taken up by noradrenergic fibers as well. This was confirmed in studies involving superior cervical ganglionectomy. It is concluded that 5-HT is taken up by both serotonergic and adrenergic fibers of the iris-ciliary body. In the presence of lithium, 5-HT stimulated an increase in the 3H-inositol phosphate accumulation in a dose-dependent manner in tissue where the phosphoinositide pool was labeled with 3H-inositol. A variety of agonists and antagonists were used to show that the 5-HT response is mediated, at least partly, by 5- HT2 receptors. The 5-HT-mediated effect on inositol phosphates is unaffected by superior cervical ganglionectomy. The effect of noradrenaline, which also stimulates inositol phosphate accumulation (but via alpha 1-adrenergic receptors in the iris-ciliary body), was elevated following superior cervical ganglionectomy.