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SL Cuthbertson, JA Cavani, C Toledo, JC Bittencourt, PD R Gamlin, A Reiner; Comparative Studies of Urocortin and Choline Acetyltransferase Indicate Urocortin not to be Localized in Neurons of the Nucleus of Edinger-Westphal . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2625.
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Purpose:The nucleus of Edinger-Westphal (EW) is the autonomic part of the oculomotor complex, and it gives rise to preganglionic input to the ciliary ganglion (CG) that regulates the lens, pupil, and choroid (Reiner et al., TINS 1983). EW neurons are cholinergic and contain choline acetyltransferase (ChAT). Recently, the neuropeptide urocortin (URO) was found in rat midbrain neurons that were identifed as belonging to EW (Yamamoto et al., Neurosci. Lett., 1998). These URO+ neurons project to spinal cord, raising uncertainty about whether they truly are the cell group innervating CG and traditionally termed EW. We sought to determine if URO is in fact present in those cholinergic midbrain neurons that innervate CG in rat, monkey and pigeon. Methods:Single- and double-label immunostaining for ChAT and URO was carried out on rat, pigeon and monkey tissue to determine if EW neurons projecting to CG contain URO. The location of EW neurons projecting to CG in pigeons is well documented, and in monkeys we identified EW by retrograde transneuronal labeling with WGA from the eye. Results:ChAT+ and URO+ neurons were co-distributed along the midline of the rostral midbrain. Nonetheless, ChAT+ neurons within the EW region projecting to CG did not contain URO. Moreover, URO+ neurons tended to be located more medially and rostrally than the cholinergic neurons of EW. The location of URO+ neurons in both birds and rats coincided with a rostral midbrain region known to project to spinal cord, but not to CG (Cabot et al., Prog. Brain Res., 1982). Conclusion:URO is not found in EW neurons in monkeys and pigeons, in which EW is defined as the population of accessory oculomotor neurons projecting to the ciliary ganglion. Similarly, our immunohistochemical labeling reveals that URO is also not located within cholinergic preganglionic neurons of the rat oculomotor complex. Thus, urocortin is not present in EW neurons that give rise to preganglionic innervation of the CG.
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