Peripheral cortex

By GD 60, the medullary and cortical regions can easily be distinguished microscopically. The medulla contains primarily CD3-positive cells and immature Hassall s bodies. The main zone of proliferation is the peripheral cortex. The identification of CD3 immunoreactivity signifies the onset of the prenatal thymus function of educating lymphocytes to discriminate self versus foreign proteins. From GD 70 onwards, macrophages (CD68) are observed in minute numbers evenly distributed over both cortex and medulla. By GD 85, B lym-... 

Three tachykinin GPCRs, NK, NK, and NK, have been identified and cloned. AH are coupled to phosphatidjhnositol hydrolysis. The NK receptor is selective for substance P (SP) and is relatively abundant in the brain, spinal cord, and peripheral tissues. The NK receptor is selective for NKA and is present in the gastrointestinal tract, urinary bladder, and adrenal gland but is low or absent in the CNS. The NIC receptor is selective for NKB and is present in low amounts in the gastrointestinal tract and urinary bladder, but is abundant in some areas of the CNS, ie, the spinal dorsal bom, soUtary nucleus, and laminae IV and V of the cortex with moderate amounts in the interpeduncular nucleus. Mismatches in the distribution of the tachykinins and tachykinin receptors suggest the possibility of additional tachykinin receptor subtypes. 

High concentrations of KOP have been found in the cerebral cortex and hypothalamus KOP is also present in the gastrointestinal tract, in immune cells as well as in other peripheral tissues. KOPs have been implicated in the regulation of nociception, diuresis, feeding, neuroendocrine and immune system functions [2]. 

Nociceptive neurons in the spinal cord as well as in higher centres such as the thalamus and cortex can also undergo alterations in activity following chronic peripheral changes and trauma (Table 1). These changes are typically long-term in nature and lead to the clinical syndromes of centrally maintained pain (secondary hyperalgesia, allodynia, spontaneous pain). Alterations... 

High amounts of somatostatin are found in the CNS, the peripheral nervous system, the gut and the endocrine pancreas whereas the kidneys, adrenals, thyroid, submandibular glands, prostate and placenta produce rather low amounts. In particular, the hypothalamus, all limbic structures, the deeper layers of the cerebral cortex, the striatum, the periaqueductal central grey and all levels of the major sensoty pathway are brain areas that are especially rich in somatostatin. Eighty percent of the somatostatin immunoreactivity in the hypothalamus is found in cells of the anterior periventricular nucleus (Fig. 1, [1]). The gut 5 cells of the mucosa and neurons, which are intrinsic to the submucous and... 

Caffeine is a mild to potent CNS stimulant, with the degree of its stimulating effect dependent on the dose administered. Caffeine stimulates the CNS at all levels, including the cerebral cortex, die medulla, and the spinal cord. Caffeine has mild analeptic (respiratory stimulating) activity. Other actions include cardiac stimulation (which may produce tachycardia), dilatation of coronary and peripheral blood vessels, constriction of cerebral blood vessels, and skeletal muscle stimulation. Caffeine also has mild diuretic activity. 

Awad, M and Gavish, M (1987) Binding of [ H]Ro 5-4864 and [ H]PK 11195 to cerebral cortex and peripheral tissues of various species species differences and heterogeneity in peripheral benzodiazepine binding sites. J. Neurochem. 49 1407-1414. 

As discussed, the first-order neuron is the afferent neuron that transmits impulses from a peripheral receptor toward the CNS. Its cell body is located in the dorsal root ganglion. This neuron synapses with the second-order neuron whose cell body is located in the dorsal horn of the spinal cord or in the medulla of the brainstem. The second-order neuron travels upward and synapses with the third-order neuron, whose cell body is located in the thalamus. Limited processing of sensory information takes place in the thalamus. Finally, the third-order neuron travels upward and terminates in the somatosensory cortex where more complex, cortical processing begins. 

NGF also has actions within the CNS, although it is not particularly abundant in the CNS. Its synthesis appears to be largely restricted to the hippocampus and neocortex, and even in these regions it is present at relatively low concentrations relative to the other neurotrophins. The most prominent population of NGF-responsive neurons expressing TrkA are the basal forebrain cholinergic neurons. The principal projections of these neurons are to the hippocampus and cortex, which conforms with the concept that NGF acts as a target-derived trophic factor in the CNS, just as it does in the peripheral nervous system (PNS). NGF also acts on a subpopulation of cholinergic neurons within the striatum. These interneurons express the NGF receptor, TrkA, and respond to NGF. However, they do not appear to rely entirely on NGF for their survival, and the specific actions of NGF on this neuronal population have not been clearly defined. NGF may also have autocrine actions in the CNS, as some neuronal populations have been identified that express both TrkA and NGF. 

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