Locus coeruleus distribution

Two AT-II receptors, AT and AT2 are known and show wide distribution (27). The AT receptor has been cloned and predominates ia regions iavolved ia the regulation of blood pressure and water and sodium retention, eg, the aorta, Hver, adrenal cortex, and ia the CNS ia the paraventricular nucleus, area postrema, and nucleus of the soHtary tract. AT2 receptors are found primarily ia the adrenal medulla, utems, and ia the brain ia the locus coeruleus and the medial geniculate nucleus. AT receptors are GCPRs inhibiting adenylate cyclase activity and stimulating phosphoHpases C, A2, and D. AT2 receptors use phosphotyrosiae phosphatase as a transduction system. 

Figure 8.2 The distribution of noradrenergic neurons in the brain. The cell bodies are clustered in nuclei (A1 A7) in the pons/medulla regions of the brainstem and their axons project both rostrally and caudally to most regions of the neuraxis. The major nucleus is the locus coeruleus...

Wiklund, L. Leger, L. and Persson, M. Monoamine cell distribution in the cat brain stem. A fluorescence histochemical study with quantification of indolaminergic and locus coeruleus cell groups. J Comp Neurol 203 613-647, 1981. 

Norepinephrine is made in cells located in the brain stem, mostly in a group of cells called the locus coeruleus. These neurons send widespread projections throughout the brain. This distribution has functional consequences. Small disturbances in the locus coeruleus can have a large impact on many different brain areas at the same time, and thus influence many behaviors. Disorders of emotion and mood are similar in that they simultaneously impact many different behaviors. Therefore, it is reasonable to suggest that norepinephrine might affect emotion in some ways. 

Autoradiography, in situ hybridization, western blot analysis, and immunohistochemical studies have described the distribution of sigma receptors in the brain (Samovilova et al., 1985 Largent et al., 1986 Jansen et al., 1991 Bouchard and Quirion, 1997 Alonso et al., 2000 Zamanillo et al., 2000). The al receptor is expressed in septum, olfactory bulb, hypothalamus, anterodorsal thalamic nucleus, dorsal raphe, locus coeruleus, substantia nigra, and the cerebellum. 

Nonadrenergic neurons in the cenhal nervous system are restricted to the brainstem, especially at the locus coeruleus (LC). They provide the extensive noradrenergic innervation found in the cortex, hippocampus, thalamus, cerebellum, and spinal chord. The remaining neurons are distributed in the tegmental region. They innervate predominantly the hypothalamus, basal forebrain and spinal chord. LC receives affer-ents from the sensory systems that monitor the internal and... 

NE Innervation Pattern and Receptor Distribution A significant modulatory input to the MOB is from the pontine nucleus, locus coeruleus (LC). In the rat, all LC neurons contain the neurotransmitter, norepinephrine (NE) LC contains the largest population of NE neurons in the brain. It has been estimated that up to 40% of LC neurons (400-600 of a total of 1,600 LC neurons) project to the bulb in the rat (Shipley et al., 1985). A subset of LC neurons projecting to MOB contain NPY (Bouna et al., 1994). NE fibers terminate in MOB with laminar specificity. LC axons project mainly to the subglomerular layers of the bulb, particularly the IPL and GCL (McLean et al., 1989). The EPL and MCL are moderately innervated, whereas the GL is nearly devoid of NE input. 

Fig. 50. Distribution of GluR5 (A), GluR6 (B), GluR7 (C), KA-1 (D), KA-2 (E) of subunits in RNAs of high-affinity kainate receptor mRNAs in coronal sections at level of the cerebellum of the rat. Gr, granular layer LC, locus coeruleus Mol, molecular layer P, Purkinje cell layer Po, pontine nuclei. Scale bars 2.3 mm. Wisden and Seeburg (1993).

Fig. 6. Autoradiographic localization of a-1 and a-2 adrenoceptors in the area of the locus coeruleus. Frame (B) is a bright-field micrograph showing the cerebellum (CB), the mesencephalic nucleus of the trigeminal nerve (NTM), and the locus coeruleus (asterisk is placed immediately to its right). Bar = 100 pm. In (A), the a-2 adrenoceptor distribution (receptors labeled with [ HJclonidine) is shown. Note the strikingly high level of a-2 adrenoceptors in the locus coeruleus. By contrast, the a-1 receptors shown in (C) are not elevated in the locus coeruleus. Blanks are shown in (D) for a-2 receptors and in (E) for a-1 receptors. Note that the level of a-1 adrenoceptors in (C) is quite close to the blank value shown in (E). (Reproduced from Young and Kuhar, 1980o.)...

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