Brain cholinergic activity

Russell RW, Pechnick R, Jope RS Effects of lithium on behavioral reactivity relation to increases in brain cholinergic activity. Psychopharmacology 73 120-125, 1981 Russell VA, Lamm MC, Taljaard JJ Lack of interaction between alpha 2-adrenoceptors and dopamine D2-receptors in mediating their inhibitory effects on [ H] dopamine release from rat nucleus accumbens. Neurochem Res 18 285-289, 1993... 

Dementia with Lewy bodies (DLB) is considered the second most common cause of dementia after AD. The disorder is characterized by progressive fluctuating cognitive impairment, visual hallucinations and motor features of Parkinsonism. Neocoitical cholinergic activity is more severely depleted in DLB than in AD, and DLB also affects the caudate nucleus, the thalamus and the brain stem. Tolerability of ChEI in DLB appears similar to AD, with some gastrointestinal effects and muscle cramps. 

Compounds that affect activities of hepatic microsomal enzymes can antagonize the effects of methyl parathion, presumably by decreasing metabolism of methyl parathion to methyl paraoxon or enhancing degradation to relatively nontoxic metabolites. For example, pretreatment with phenobarbital protected rats from methyl parathion s cholinergic effects (Murphy 1980) and reduced inhibition of acetylcholinesterase activity in the rat brain (Tvede et al. 1989). Phenobarbital pretreatment prevented lethality from methyl parathion in mice compared to saline-pretreated controls (Sultatos 1987). Pretreatment of rats with two other pesticides, chlordecone or mirex, also reduced inhibition of brain acetylcholinesterase activity in rats dosed with methyl parathion (2.5 mg/kg intraperitoneally), while pretreatment with the herbicide linuron decreased acetylcholine brain levels below those found with methyl parathion treatment alone (Tvede et al. 1989). 

Greene, R. W., Gerber, U. McCarley, R. W. (1989). Cholinergic activation of medial pontine reticular formation neurons in vitro. Brain Res. 476, 154-9. 

Durkin T. 1992. GABAergic mediation of indirect transsynap-tic control over basal and spatial memory testing-induced activation of septo-hippocampal cholinergic activity in mice. Behavioral Brain Research 50(1-2) 155-165. 

Mecfianism of Action Levodopa is converted to dopamine in the basal ganglia thus increasing dopamine concentration in brain and inhibiting hyperactive cholinergic activity. Carbidopa prevents peripheral breakdown of levodopa, allowing more levo-dopa to be available for transport into the brain. Therapeutic Effect Reduces tremor and other symptoms of Parkinson s disease. 

Mechanism of Action A dopamine prodrug that is converted to dopamine in basal ganglia. Increases dopamine concentrations in the brain, inhibiting hyperactive cholinergic activity. Therapeutic Effect Decreases signs and symptoms of Parkinson s disease. 

The cholinergic neurons are immediately distal to dopaminergic fibres in the caudate nucleus in brain. They are excitatory and in parkinsonism, there is a degeneration of inhibitory dopaminergic neurons and thus, there is increased cholinergic activity (preponderance of cholinergic system) which results in the symptoms of parkinsonism. 

Strong et al. 1996). Studies in these animals indicate that exposure to aluminum can affect permeability of the blood-brain barrier, cholinergic activity, signal transduction pathways, lipid peroxidation, and glucose metabolism, as well as interfere with metabolism of essential trace elements (e.g., iron) because of similar coordination chemistries and consequent competitive interactions. Signal pathways are important in all cells and control differentiation and proliferation, neurotransmitter release,... 

Jope, R. S., Song, L. and Powers, R. E. (1997) Cholinergic activation of phospho-inositide signaling is impaired in Alzheimer s disease brain. Neurobiol Aging 18, 111-120. 

The brain of AD patients is also characterized by the degeneration of basal forebrain cholinergic neurons, which innervates central regions involved in cognitive functions such as the cortex amygdala and hippocampus (1,3). The decline of cortical cholinergic activity as measured in postmortem brains... 

While normal cholinergic activity in the brain is essential for its normal functioning, strong activation of the cholinergic system in the CNS leads to loss of consciousness, to epilepsy-type convulsions, to muscular fasciculations (CNS-caused) and to down-regulation of the breathing center. 

Our dreams are emotional, and something that psychologists term hyperassociative , because our brains are activated by cholinergic rather than aminergic chemicals. Thus, we restore the most fundamental aspects of our cognitive capability - the capacity to order our memories in a way that serves survival. Emotional salience or relevance is a general mnemonic rule. Our level of emotional competence has a high survival value and underlies the more precise information needed to function socially. In other words, we need, first and foremost, to know when to approach, when to mate, when to be afraid, and when to run for cover. These... 

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