Nicotinic receptors attention

Nicotine also affects the developing fetus. Adverse effects of chronic nicotine consumption during pregnancy include reduced infant birth weight, attention deficit disorders, and other cognitive problems. Nicotine receptors are expressed early during development, and it is not clear what other effects nicotine exposure during development has on the fetus. 

Most of the anticholinergic drugs which cause delirium have prominently antimuscarinic actions. However, nicotinic receptors are also present in the brain. Mecamylamine, a nicotinic receptor antagonist which penetrates the brain to some extent, has produced delirium (Paykel et al., 1982). Furthermore, general (inhalational) anaesthetics, which by definition decrease arousal, target nicotinic receptors among others (Chapter 9). Conversely, nicotine itself increases arousal and selective attention (Ashton, 1992b). 

Recent research has indicated select abnormalities in the cholinergic system (Perry et al., 2001). Although previously unexamined neurochemically, there was an indication that the cholinergic system may be involved in autism, with abnormalities reported in neurons in the basal forebrain (Bauman Kemper, 1994). Perry et al. (2001) found extensive loss of high affinity nicotinic receptors from the neocortex (frontal and parietal), and from the cerebellum (Lee, et al., in preparation). Nicotinic receptors are implicated in attention, and also consciousness as many general anaesthetics block the receptor channel (Chapter 9). 

These results suggest that the deficits produced by mecamylamine resemble in several respects those seen in AD and to a lesser extent in PD. Deficits in short- and long-term memory, impaired attention, liberal response bias, and decreases in reaction time are hallmarks of the dementing picture seen in these disorders. The age-related nature of some of the findings suggest that the decline in nicotinic receptors with age produces increased vulnerability to the effects of nicotinic blockade. 

It has been suggested that abnormalities in attention-deficit/hyperactivity disorder in children and adults may be similar to those seen in early stages of PD (McCracken 1991). Of interest is that nicotinic mechanisms interact closely with dopamine systems (Kirch et al. 1988) and that nicotinic receptors may serve to regulate dopamine release (Clarke and Pert 1985 Rapier et al. 1990) in striatal and mesolimbic pathways. Nicotine is now being tried as an experimental treatment for attention-deficit/hyperactivity disorder in adults (Levin et al. 1995). 

On each experimental day, the Repeatable Battery for Assessment of Neuropsychological Status (RBANS) was administered (Randolph, 1998). It assesses attention, immediate memory, visuospatial/ construction, language, and delayed memory (Gold et al., 1999). Schizophrenics score significantly lower than normal subjects the decrement is correlated with diminished psychosocial status. Compared to placebo, the DMXB-A significantly improved overall performance and specifically improved function on the Attention subscale. Inhibition of the P50 response to repeated stimulus, the sensory gating measure that led to identification of nicotinic receptor deficits in schizophrenia, also improved (Olincy et al., 2006). 

Ellis JR, Ellis KA, Bartholomeusz CF, Harrison BJ, Wesnes KA, et al. 2006. Muscarinic and nicotinic receptors synergistically modulate working memory and attention in humans. Int J Neuropsychopharmacol 9 175-179. 

Sacco KA, Termine A, Seyal A, Dudas MM, Vessicchio JC, et al. 2005. Effects of cigarette smoking on spatial working memory and attentional deficits in schizophrenia Involvement of nicotinic receptor mechanisms. Arch of Gen Psychiatry 62 649-659. 

Actions at nicotinic receptors enhance not only the release of acetylcholine but also that of ofher neurotransmitters, which may boost attention and improve behaviors caused by deficiencies in those neurotransmitters in Alzheimer disease... 

The biological activity of class A alkaloids as non-competitive blockers for nicotinic receptor-chaimels has been known for years [5] and the attention has now turned to the biological activity of class B alkaloids. 

Alzheimer s disease has received the most attention as a therapeutic target for nicotinic drugs, as nicotinic receptor binding was found to be significantly reduced in distinct brain regions of Alzheimer s patients. Because the... 

These studies represent significant evidence that stimulation of nicotinic receptors can improve the acquisition and retention of verbal (declarative) and non-verbal information in humans. The role of attentional effects of nicotinic stimulation has been stressed by Sahakian and Coull (1994). However, as has been suggested by Warburton and... 

Given the attentional improvement that has been demonstrated with nicotinic receptor stimulation, there are implications for nicotine or novel nicotinic agonists as a possible treatment strategy in attention deficit-hyperactivity disorder (ADHD). This is a disorder primarily of children, but affects adults as well. ADHD afflicts as many as 3-5% of American children (American Psychological Association, 1994) and is characterized by inattention, restlessness, impulsiveness and hyperactivity. There is sig-... 

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