Plant-derived extracts in the neuroscience of anxiety on animal models: biases and comments

The Use of Larval Zebrafish (Danio rerio) Model for Identifying New Anxiolytic Drugs from Herbal Medicine

Anxiety is a widespread psychiatric disorder. The search for a cure is still continuing since many of the synthetic drugs were inefficient in completely treating anxiety, yet caused some dangerous side effects until many of the drugs were withdrawn from the market. One promising source of new anxiolytics could be herbal medicines. The challenge is to screen plant extracts. Rodent models can be used for this purpose but are expensive. Moreover, rodent tests are costly and consume relatively large quantities of sample. For this reason, alternative animal models may be useful. Zebrafish larvae have many advantages for screening natural products. The main advantage is that they can be produced cheaply and in large numbers. Several studies have shown that the zebrafish is a good model for studying drugs that affect anxiety. This review focuses on the use of animal models, including zebrafish larvae, for studying anxiety and screening for herbal medicines that modulate anxiety. Finally, future prospects of the zebrafish larva as an alternative model in this field are also discussed.

Bias and misleading concepts in an Arnica research study. Comments to improve experimental Homeopathy

Basic experimental models in Homeopathy are of major interest because they could get insightful data about the ability of high dilutions to work in a biological system. Due to the extreme difficulty in the highlighting any possible effect and trusting its reliability, methods should be particularly stringent and highly standardized. Confounders, handling process, pre-analytical errors, misleading statistics and misinterpretations may lead to experimental biases. This article tries to elucidate those factors causing bias, taking into account some recent reported evidence in the field.

Experimental neuropharmacology of Gelsemium sempervirens: Recent advances and debated issues

Gelsemium sempervirens L. (Gelsemium) is traditionally used for its anxiolytic-like properties and its action mechanism in laboratory models are under scrutiny. Evidence from rodent models was reported suggesting the existence of a high sensitivity of central nervous system to anxiolytic power of Gelsemium extracts and Homeopathic dilutions. In vitro investigation of extremely low doses of this plant extract showed a modulation of gene expression of human neurocytes. These studies were criticized in a few commentaries, generated a debate in literature and were followed by further experimental studies from various laboratories. Toxic doses of Gelsemium cause neurological signs characterized by marked weakness and convulsions, while ultra-low doses or high Homeopathic dilutions counteract seizures induced by lithium and pilocarpine, decrease anxiety after stress and increases the anti-stress allopregnanolone hormone, through glycine receptors. Low (non-Homeopathic) doses of this plant or its alkaloids decrease neuropathic pain and c-Fos expression in mice brain and oxidative stress. Due to the complexity of the matter, several aspects deserve interpretation and the main controversial topics, with a focus on the issues of high dilution pharmacology, are discussed and clarified.

On Gelsemium and Complementary and Alternative Medicine (CAM) in Anxiety and Experimental Neurology

A recent discussion expanded the debate about the experimental research on Gelsemium in anxiety. Herbal medicine is widely used in anxiety and mood disorders, often with contradictory evidence, although some authors are yet prompted to promote their full introduction in pharmacology as a promising therapy. Complementary and alternative medicine (CAM) in anxiety is particularly appreciated by individual healthcare, but deserves further investigation, as many critical issues have been recently raised. Comments about the ability of negligible doses of Gelsemium hydroalcoholic extracts to affect gene expression were recently reported.

Social isolation after stroke leads to depressive-like behavior and decreased BDNF levels in mice

Social isolation prior to stroke leads to poorer outcomes after an ischemic injury in both animal and human studies. However, the impact of social isolation following stroke, which may be more clinically relevant as a target for therapeutic intervention, has yet to be examined. In this study, we investigated both the sub-acute (2 weeks) and chronic (7 weeks) effects of social isolation on post-stroke functional and histological outcome. Worsened histological damage from ischemic injury and an increase in depressive-like behavior was observed in isolated mice as compared to pair-housed mice. Mice isolated immediately after stroke showed a decrease in the levels of brain-derived neurotrophic factor (BDNF). These changes, both histological and behavioral, suggest an overall negative effect of social isolation on stroke outcome, potentially contributing to post-stroke depression and anxiety. Therefore, it is important to identify patients who have perceived isolation post-stroke to hopefully prevent this exacerbation of histological damage and subsequent depression.