Comparison of the distributions of urocortin‐containing and cholinergic neurons in the perioculomotor midbrain of the cat and macaque

Abstract

Urocortin is a novel neurotransmitter that appears to play a role in eating and drinking behavior. Most urocortin-positive (urocortin(+)) neurons in rodents are found in the cytoarchitecturally defined Edinger-Westphal nucleus (EW). However, the EW is traditionally described as the source of the preganglionic parasympathetic outflow to the ciliary ganglion. We examined the distribution of urocortin(+) cells and motoneurons by use of immunohistochemical staining for this peptide and for choline acetyltransferase (ChAT) in macaque monkeys, in which most preganglionic motoneurons inhabit the EW, and in cats, in which most do not. In both species, lack of overt double labeling indicated that the ChAT(+) and urocortin(+) cells are separate populations. In the monkey, most nonoculomotor ChAT(+) neurons were found within the EW. In contrast, urocortin(+) cells were distributed mainly between the oculomotor nuclei and in the supraoculomotor area. In the cat, most nonoculomotor ChAT(+) cells were located in the supraoculomotor area and anteromedian nucleus. Few were present in the cat EW. Instead, this nucleus was filled with urocortin(+) cells. These results highlight the fact the term EW has come to indicate different nuclei in different species. Consequently, we have adopted the identifiers preganglionic (EW(PG)) and urocortin-containing (EW(U)) to designate the cytoarchitecturally defined EW nuclei in monkeys and cats, respectively. Furthermore, we propose a new open-ended nomenclature for the perioculomotor (pIII) cells groups that have distinctive projections and neurochemical signatures. This will allow more effective scientific discourse on the connections and function of groups such as the periculomotor urocortin (pIII(U)) and preganglionic (pIII(PG)) populations.

Unique responses of midbrain CART neurons in macaques to ovarian steroids

“…In monkey, the Edinger-Westphal nucleus contains choline acetyltransferase-positive, presumed pre-ganglionic neurons of the ciliary ganglion whereas the human Edinger-Westphal consists of noncholingeric urocortin-positive neurons (Horn et al, 2008). We found that the anatomical distribution of the midbrain CART neurons in the monkey is identical to that of the midbrain urocortins-1 neurons as recently described (May et al, 2008). Hence in monkey, midbrain CART neurons are located between the Edinger-Westphal nucleus and the occulomotor (III) nucleus.…”

“…A diagram showing the relative positions of the periaquaductal gray (PAG), Edinger-Westphal nuclei (EW), the occulomotor nuclei (III) and the CART neurons (dots) is shown below the montages. The area where the CART positive neurons are located has been referred to as the supraocculomotor area, or SOA (May et al, 2008). The montages were built automatically by Slidebook 4.2 and the stereology microscope.…”

Interactions of Corticotropin-Releasing Factor, Urocortin and Citalopram in a Primate Model of Stress-Induced Amenorrhea

“…Sections were then incubated for 48 h in primary antibody to UCN1 (U4757; Sigma) or CRF (gift of Wylie Vale; Salk Institute, La Jolla, Calif., USA). These antibodies have been extensively characterized and previously applied to primate brain [37,38,39]. The UCN1 antibody was diluted 1/15,000 in 0.6% normal goat serum, 0.02 M KPBS and 0.4% Triton.…”

Defining the pupillary component of the perioculomotor preganglionic population within a unitary primate Edinger–Westphal nucleus

“…In order to better determine the true identity of EW, we recently investigated the populations of neurons found in the vicinity of the oculomotor nucleus, the perioculomotor (pIII) populations, in the cat and monkey (May et al, 2008). Specifically, we compared the locations of the cholinergic and urocortin peptidergic populations by using antibodies to choline acetyl transferase (ChAT) and urocortin I.…”