Thalamus human

Hi-receptors in the adrenal medulla stimulates the release of the two catecholamines noradrenaline and adrenaline as well as enkephalins. In the heart, histamine produces negative inotropic effects via Hr receptor stimulation, but these are normally masked by the positive effects of H2-receptor stimulation on heart rate and force of contraction. Histamine Hi-receptors are widely distributed in human brain and highest densities are found in neocortex, hippocampus, nucleus accumbens, thalamus and posterior hypothalamus where they predominantly excite neuronal activity. Histamine Hrreceptor stimulation can also activate peripheral sensory nerve endings leading to itching and a surrounding vasodilatation ( flare ) due to an axonal reflex and the consequent release of peptide neurotransmitters from collateral nerve endings. 

Anandamide is found in human brain 100 pmol/g in the hippocampus, 75 pmol/g in the thalamus, 60 pmol/g in the cerebellum, and 55 pmol/g in the striatum (Martin, 1999). The concentration of AEA increases postmortem, especially when the brain is kept at ambient temperature. Furthermore, AEA surges are observed when cerebellar granule cells are treated in hypoxic conditions (Hillard, 1997). Although such concentration increases may be artifacts of postmortem brain damage, they may also occur in living tissue under certain conditions, such as hypoxia. 

As its name suggests, the hypothalamus lies beneath the thalamus and above the pituitary gland. Although it is quite small, accounting for only about 4 g of the total 1400 g of the adult human brain, it plays a vital role in maintenance of homeostasis in the body. It is composed of numerous cell groups and fiber pathways, each with a specific function. 

Narcolepsy, a sleep disorder characterized by excessive daytime sleepiness and cataplexy, may be caused by the lack of hypocretin mRNA and peptides in humans (Peyron et al., 2000) or a disruption of the hypocretin receptor 2 or its ligand in dogs and mice (Lin et al., 1999 Chemelli et al., 1999). Hypocretin-containing neurons are located exclusively in the dorsomedial, lateral, and perifornical hypothalamic areas (Peyron et al., 1998). Two hypocretin sequences, Hcrt-1 (orexin-A) and Hcrt-2 (orexin-B), are generated from a single preprohypocretin (De Lecea et al., 1998 Peyron et al, 1998 Sakurai et al, 1998). Axons from these neurons are found in the hypothalamus, locus coeruleus (LC), raphe nuclei, tuberomamillary nucleus, midline thalamus, all levels of spinal cord, sympathetic and parasympathetic centers, and many other brain regions... 

FIGURE 1-1 Coronal section of the human brain at the thalamic level stained by the Heidenhain technique for myelin. Gray matter stains faintly, all myelinated regions are black. The thalamus ( ) lies beneath the lateral ventricles and is separated at this level by the beginning of the third ventricle. The roof of the lateral ventricles is formed by the corpus callosum (small arrows). Ammon s horns are shown by the large arrows. Note the outline of gyri and sulci at the surface of the cerebral hemispheres, sectioned here near the junction of the frontal and parietal cortices. 

Figure 18.7 Distribution of iron in human brain. GP, globus pallidus SN, substantia nigra IPN, interpeduncular nucleus TH, thalamus DG, dentate gyrus RN, red nucleus CC, cerebral cortex HIPP, hippocampus CER, cerebellum FC, frontal cortex. (From Crichton and Ward, 2006. Reproduced with permission from John Wiley Sons., Inc.)...

CYP21 mRNA expressed in human amygdala, caudate nucleus, cerebellum, corpus callosum, hippocampus, spinal cord, and thalamus (Yu et al., 2002). 

CYP2D6 mRNA and protein in human brain regions by RT-PCR, Northern blot, and Immunobiot, in situ hybridization and IHC shows constitutive CYP2D6 mRNA expression in neurons of cerebral cortex, Purkinje and granule cell layers of cerebellum, reticular neurons of midbrain and pyramidal neurons of C47, CA2, and CAS subfields of hippocampus. Protein found in cortex, cerebellum, midbrain, striatum, and thalamus of human brain. IHC shows CYP2D6 in dendrites of Purkinje and cortical neurons and neuronal soma (Chinta et al., 2002). 

Meyerson BA, Linderoth B, Karlsson H, Ungerstedt U. 1990. Microdialysis in the human brain extracellular measurements in the thalamus of parkinsonian patients. Life Sci 46(4) 301-308. 

Figure 1.2 presents a coronal section through the human brain. In brief, the brain may be divided into the brainstem (consisting of the medulla, pons and midbrain) that is linked to the diencephalon which is composed of the thalamus and the hypothalamus. The two cerebral hemispheres are linked by the corpus callosum, a large tract of nerve fibres that enables the two... 

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