Handbook of experimental pharmacology
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Handb Exp Pharmacol · Jan 2014
ReviewAnimal toxins influence voltage-gated sodium channel function.
Voltage-gated sodium (Nav) channels are essential contributors to neuronal excitability, making them the most commonly targeted ion channel family by toxins found in animal venoms. These molecules can be used to probe the functional aspects of Nav channels on a molecular level and to explore their physiological role in normal and diseased tissues. This chapter summarizes our existing knowledge of the mechanisms by which animal toxins influence Nav channels as well as their potential application in designing therapeutic drugs.
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Handb Exp Pharmacol · Jan 2014
ReviewHow positive and negative expectations shape the experience of visceral pain.
Knowledge from placebo and nocebo research aimed at elucidating the role of treatment expectations and learning experiences in shaping the response to visceral pain fills an important research gap. First, chronic abdominal pain, such as in irritable bowel syndrome (IBS), is highly prevalent, with detrimental individual and socioeconomic impact and limited effective treatment options. At the same time, IBS patients show high placebo response rates in clinical trials and benefit from placebo interventions. ⋯ Hence, the study of nocebo and placebo effects in visceral pain constitutes a model to assess the contribution of psychological factors. Herein, the clinical relevance of visceral pain is introduced with a focus on IBS as a bio-psycho-social disorder, followed by a review of existing clinical and experimental work on placebo and nocebo effects in IBS and in clinically relevant visceral pain models. Finally, emerging research trends are highlighted along with an outlook regarding goals for ongoing and future research.
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Recent substantial laboratory and theoretical research hints for different learning mechanisms regulating the formation of placebo and nocebo responses. Moreover, psychological and biological variants may play a role as modulators of learning mechanisms underlying placebo and nocebo responses. In this chapter, we present pioneering and recent human and nonhuman research that has impressively increased our knowledge of learning mechanisms in the context of placebo and nocebo effects across different physiological processes and pathological conditions.
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Handb Exp Pharmacol · Jan 2014
Lessons to be learned from placebo arms in psychopharmacology trials.
Large placebo effects are typically reported in clinical drug trials and evidence suggests placebo effects have increased over time. The diminishing drug-placebo difference calls into question the effectiveness of pharmacological treatments and provides a challenge to prove the effectiveness of new medications. This chapter discusses explanations for the increasing placebo effect. ⋯ It is argued that specific and nonspecific effects interact in drug groups of clinical trials. This interaction influences drug-placebo differences in clinical trials (i.e., trial sensitivity). Future research should aim to identify which patients will respond best to drugs and those who may be better treated with placebos.
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Handb Exp Pharmacol · Jan 2014
Placebo and nocebo effects: an introduction to psychological and biological mechanisms.
Placebo and nocebo effects are essential components of medical practice and efficacy research, and can be regarded as a special case of context learning. A fundamental function of the central nervous system is to configure the way in which previous learned context becomes linked to corresponding responses. ⋯ Given the fact that contextual learning originates in the brain, neuroimaging tools have been widely used to study placebo and nocebo effects. In addition, pretest resting state fMRI may be a valuable biomarker to predict placebo responses.