Sensory neurons, peripheral

Neuregulins are highly expressed in the nervous system by neuroblasts, cortical neurons, peripheral sensory ganglionic cells and spinal motor neurons as well as myelinforming glia. 

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. 

Peripheral Gl, vascular and bronchial smooth muscle, vascular endothelium, platelets Peripheral Smooth muscle of ileum, stomach fundus (rat), uterus, vasculature, endothelium Peripheral None identified Peripheral Post-ganglionic sympathetic neurons, sensory neurons Peripheral Cardiac muscle, post-ganglionic parasympathetic neurons (myenteric plexus), esophageal and vascular smooth muscle... 

Neuropathic pain states are thought to be generated in the peripheral sensory neurons by events within the nerve itself and so are independent of peripheral nociceptor activation. Damage to peripheral nerves can be caused by a number of pathological, metabolic and viral causes. According to the terminology guide of the International... 

Although histamine is not stored in neurons outside of the central nervous system, mast-cell-derived histamine can modify peripheral sensory nerve function. Both acute and chronic pain states can result from inflammation or peripheral nerve cell injury, and there is substantial evidence that mast cell histamine participates in these disorders. 

The specific actions of the individual neurotrophins have been the subject of intense interest (Table 27-2). It is now evident, through analysis of animals in which the individual neurotrophin genes or their receptors have been knocked out, that the family members have unique actions acting exclusively to support some neuronal subpopulations [11]. However, in some neuronal populations, the action of several of the neurotrophins overlap. For example, in the peripheral sensory ganglia, individual neurons are responsive to more than one neurotrophin. 

Brain-derived neurotrophic factor was identified on the basis of its ability to stimulate process outgrowth from peripheral sensory neurons. It was isolated from brain and, upon analysis of its structure, discovered to be highly homologous to NGF [3]. BDNF has a different spectrum... 

In the periphery, NT3 uniquely supports proprioceptive neurons in sensory ganglia. These neurons and their peripheral targets, the muscle sensory organs, are lost in NT3 knockout mice. Mice in which the NT3 receptor TrkC has been knocked out do not live long and have abnormal movements as a consequence of their loss of proprioception. 

Pharmacology Capsaicin is a natural chemical derived from plants. Although the precise mechanism of action is not fully understood, evidence suggests that the drug renders skin and joints insensitive to pain by depleting and preventing reaccumulation of substance P in peripheral sensory neurons. 

Peripheral neuropathy (degeneration of peripheral sensory and/or motor neurons) represents another target for neurotrophic intervention. It often occurs as a complication of diabetes or in cancer patients receiving chemotherapy. In severe cases, amputation of limbs affected by neuronal loss is warranted. Pre-clinical studies have clearly shown that sensory and sympathetic neurons depleted in peripheral neuropathy respond to NGF. Indeed, NGF, along with IGF-1, can prevent the occurrence of drug-induced peripheral neuropathy in animals. Human clinical trials continue. 

Mechanism of Action An analgesic that depletes and prevents reaccumulation of the chemomediator of pain impulses (substance P) from peripheral sensory neurons to CNS. Therapeutic Effect Relieves pain. 

Mutations in motor proteins or IFs themselves (which may alter their associations with IFAPs or motors) lead to accumulations of IFs in ALS, Charcot-Marie Tooth disease 2, and Parkinson s (Goldstein and Yang, 2000 Helfand et al., 2004). Impaired assembly and transport of NFs is a critical determinant of neurodegenerative disease. Consistent with a critical role for kinesin in vivo, mice lacking the neuronal-specific conventional kinesin heavy chain KIF5A were shown to have accumulations of NF-H, as well as NF-M and NF-L, in the cell bodies of peripheral sensory neurons. The presence of these accumulations was accompanied by a reduction in... 

Peters, C. M., Jimenez-Andrade, J. M., Jonas, B. M., Sevcik, M. A., Koewler, N. J., Ghilardi, J. R., Wong, G. Y., and Mantyh, P. W. (2007). Intravenous paclitaxel administration in the rat induces a peripheral sensory neuropathy characterized by macrophage infiltration and injury to sensory neurons and their supporting cells. Exp. Neurol. 203, 42—54. 

The peripheral sensory neurons that supply the chemoreceptors in the oral cavity reside in four distinct cranial ganglia (Figure 4). The trigeminal ganglion contains the sensory... 

The property of drugs that allows these adaptive differences with conventional reinforcers is a basic one drugs enter the brain and directly activate or disinhibit DA neurons. In contrast, for their effects on DA neurons, conventional reinforcer drugs depend on the stimulation of a long chain of neurons triggered by stimulation of peripheral sensory receptors. 

Krinke G, Schaumburg HH, Spencer PS, Suter J, Thomann O, and Hess R (1980) Pyridox-ine megavitaminosis produces degeneration of peripheral sensory neurons (sensory neuropathy) in the dog. Neurotoxicology 2,13-24. 

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