Progress in brain research
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This chapter describes current findings from the research into postoperative cognitive dysfunction (POCD) following cardiac and non-cardiac surgery in older adults. The evidence suggests that a significant proportion of patients show POCD in the early weeks following surgery and anesthesia. Specific domains of cognition are affected, especially memory. ⋯ Increasing age is among the most consistently reported patient-related risk factor. Other factors more directly related to the surgery and anesthesia are likely to contribute to the pathogenesis of POCD, including inflammatory processes triggered by the surgical procedure. Animal studies have provided valuable findings otherwise not possible in human studies; these include a correlation between the inflammatory response in the hippocampus and the development of POCD in rodents.
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Impaired urinary dilution leading to water retention and hyponatremia may occur in patients with cardiac failure, cirrhosis, pregnancy, hypothyroidism, glucocorticoid and mineralocorticoid deficiency. The mechanisms for these defects predominantly involve the non-osmotic stimulation of arginine vasopressin release with upregulation of aquaporin 2 water channel expression and trafficking to the apical membrane of the principal cells of the collecting duct. ⋯ They may involve several factors, such as impaired counter-current concentration secondary to downregulation of Na-K-2Cl co-transporter. Vasopressin-resistant downregulation of aquaporin 2 expression has also been described as a factor in impaired urinary concentration.
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There has been significant recent growth in programmes evaluating preventive treatment for individuals exhibiting prodromal symptoms, at high risk of developing first-episode psychosis. Because of the tremendous human and economic burden of schizophrenia and other psychotic disorders, primary prevention modalities of even modest impact would likely have important public health consequence. Several published clinical trials suggest that antipsychotic medications have beneficial effects in either preventing or postponing the emergence of first-episode psychosis in individuals at high risk of psychosis. ⋯ In one such study, low-dose risperidone pre-treatment prevented behavioural abnormalities following neonatal hippocampal lesions, while higher risperidone pre-treatment was ineffective. These findings support the predictive validity of the neonatal hippocampal lesion model in identifying psychosis prevention interventions, provide theoretical support for the use of low-dose risperidone in prevention of first-episode psychosis and suggest the possibility that higher risperidone doses could be less effective than low dosages in this application. These observations also suggest a potential role for selective 5-HT(2A) receptor antagonists as drug development targets for psychosis prevention.
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Serotonin and dopamine are two monoamines which are known to interact with each other. Their role for suicidal behaviour, aggression and mood are reviewed in this chapter. We found a substantial amount of evidence for the relevance of a serotonin and dopamine model of aggression, and for aggression as a major risk factor for suicide. Evidence was found that serotonin and dopamine also may be involved in depressed mood, and possibly the individual's ability to cope with imminent suicidality.
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The neuropeptides arginine vasopressin (AVP) and oxytocin (OXT) are acknowledged as important modulators of diverse social behaviours. Here we discuss recent studies using intracerebral microdialysis to investigate the dynamics of AVP and OXT release patterns within distinct brain regions during the display of social behaviours in rats. Manipulation of local receptor-mediated actions of AVP and OXT via retrodialysis of either agonists or antagonists revealed the behavioural significance of changes in local neuropeptide release. ⋯ Interestingly, OXT released within the PVN during sexual activity in male rats was found to be associated with a robust decrease in anxiety-related behaviour up to 4h after mating. These data illustrate distinct modes of behavioural actions of AVP and OXT, reaching from acute regulation of the respective social behaviour to the long-term modulation of related behaviours including anxiety and social cognition. In conclusion, measuring the in vivo release patterns of AVP and OXT within distinct brain regions during the display of diverse social behaviours and manipulation of local AVP and OXT activity has yielded new insights into the specific roles of these neuropeptides in the regulation of complex social behaviours.