Peripheral nervous system, lead

Low level chronic exposme to mercury vapour can also affect the peripheral nervous system, leading to pol)meuropathy (reduced sensory and motor nerve function) and neuropsychological symptoms of stress and behaviour problems. Longer exposures, around 15 years, have been shown in several studies to lead to alterations in pulse rate, blood pressure, memory, sleep disturbance and EEGs, probably as a result of kidney and CNS (central nervous system) dysfunction. 

It is easy to speculate that in an active neuron with a rapid firing pattern, the continued release of a peptide may eventually lead to depletion of the peptide occurring. This has been shown in the peripheral nervous system. If this also happens in the CNS it would provide a mechanism whereby the release and resultant receptor effects of a transmitter no longer match the firing pattern and demands of the neuron and so could contribute to long-term adaptations of neurons by a reduction in the time over which a peptide is effective. 

Although most of the medicinal chemistry effort in the H3 receptor field has been focused on the development of antagonists, there is some interest in agonists as well. Histamine H3 receptor agonists decrease the release of histamine in the central and peripheral nervous system and lead to a weakened histaminergic tone. In the brain, their effects will therefore be comparable to those of Hi receptor antagonists, with sedation and induction of sleep as a prominent observation. Indeed, H3 agonists such as the imidazoles... 

Recycling of printer circuit boards is deemed as the most important source of heavy metals to the ambient environment. These heavy metals may be entering into human body from various exposure routes such as ingestion, inhalation, and dermal absorption. Exposure to high levels of heavy metals can lead to acute and chronic toxicity, such as damage to central and peripheral nervous systems, blood composition, lungs, kidneys, liver, and even death [14],... 

Lead (soft, Pb2+) Injuries to peripheral nervous system, disturbs heme synthesis and affects kidneys Pb2+ may replace Ca2+ with loss of functional and structural integrity. Reacts with sulfhydryl groups, replaces Zn2+ in 8-aminolevulinic acid dehydratase. 

Araki, S, Murata, K, Aono, H. (1987). Central and peripheral nervous system dysfunction in workers exposed to lead, zinc and cooper. A follow-up study of visual and somatosensory evoked potentials. Int. Arch. Occup. Environ. Health, 59, 177-87. 

In addition to the physiological process of autoinhibition, another mechanism of presynaptic inhibition has been identified in the peripheral nervous system, although its precise relevance to the brain is unclear. In the dorsal horn of the spinal cord, for example, the axon terminal of a local neuron makes axo-axonal contact with a primary afferent excitatory input, which leads to a reduction in the neurotransmitter released. This is due to the local neuron partly depolarizing the nerve terminal, so that when the axon potential arrives, the change induced is diminished, thereby leading to a smaller quantity of transmitter being released. In the brain, it is possible that GABA can cause presynaptic inhibition in this way. 

Effects of lead intoxication include damage to the central and peripheral nervous systems, to the kidneys, and to the blood-forming elements, which may lead to anemia. Symptoms include colic, loss of appetite, and constipation ... 

Adult nervous system effects are also apparent following lead exposure. In the past, painters using lead-based paint developed damage to the peripheral nervous system, which caused a wrist or foot drop. Nerve damage can be evaluated in the... 

Lee G, lingsch C, Lyle PT, et al Lithium treatment strongly inhibits choline transport in human erythrocytes. Br J Chn Pharmacol 1 365-370, 1974 Lee KF, li E, Huber J, et al Targeted mutation of the gene encoding the low affinity NGF receptor p75 leads to deficits in the peripheral nervous system. Cell 69 737-749, 1992... 

Diazinon, an anticholinesterase organophosphate, inhibits acetylcholinesterase in the central and peripheral nervous system. Inhibition of acetylcholinesterase results in accumulation of acetylcholine at muscarinic and nicotinic receptors leading to peripheral and central nervous system effects. These effects... 

Lead is a toxic metal to which there is wide exposure. Exposure is via inhalation (main source, leaded petrol) and ingestion (water, old paint). Multi-organ toxicity occurs with the kidneys, central and peripheral nervous system, testes, red cells, bones, and gastrointestinal tract all damaged. After initial distribution into red blood cells, it is eventually deposited in bone. The main biochemical effect is interference with heme synthesis at several points. Kidney toxicity may be due to lead-protein complexes and inhibition of mitochondrial function. Damage to nerves leads to peripheral neuropathy. 

Solvents, such as chlorinated hydrocarbons, toluene, benzene, and xylene, can cause a feeling of euphoria, but they can be deadly toxins. Small, daily doses may cause dizziness, mental confusion, and fatigue high doses will cause permanent damage to the central nervous system. Lead, mercury, and manganese ion poisoning will alter and destroy central and peripheral nerve function and cause personality changes. 

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