Time to Abolish the Forced Swim Test in Rats for Depression Research?

The forced swim test (FST) is a controversial rodent test that has been used for decades, mainly in depression studies. The severity of the procedure makes it ethically questionable and its validity has also been questioned. In this paper we contribute new data to this debate. We identified original research papers related to Major Depressive Disorder (MDD), using rats as models. We compared the citations received by studies that used the FST and by studies that did not, within subsequent human medical papers. The results show that the number of citations received by both groups was very low, but in the papers describing the FST data the median citation number was zero. Citation analysis indicates that the FST is not contributing significantly to the understanding or cure of MDD. We briefly review other approaches that overcome the ethical limitations of the FST, and which might also surpass its efficacy.

Exploring the side effect profile of 16-Ethynyl Salvinorin A

<p>Introduction: Drug addiction is a chronic and relapsing disorder that has widespread socioeconomic and health consequences. Globally, there are over 29.5 million people who are drug dependent, and New Zealand has one of the highest rates of drug use rates in the developed world. Currently, there are no Food and Drug Administration (FDA) approved pharmacotherapies that target psychostimulant addiction. Kappa opioid receptor (KOPr) agonists are being studied as a potential pharmacotherapy as it utilizes the brain’s own mechanism for controlling reward, however, KOPr agonists have unwanted side effects such as dysphoria and sedation. This thesis explores the KOPr agonists Salvinorin A (Sal A), a naturally-occurring, highly potent and short-acting non-nitrogenous KOPr agonist and a structural analogue, 16-Ethynyl Salvinorin A (16-Ethy). KOPr agonists, such as Sal A have known preclinical anti-addictive and anti-reward effects, therefore, this thesis focuses on evaluating Sal A and 16-Ethy in preclinical tests of reward and side effects. Methods: Male Sprague-Dawley rats were used in preclinical tests to evaluate common KOPr-mediated side-effects including anxiety (elevated plus maze), depression (forced swim test) sedation (locomotor activity) and aversion (conditioned place aversion). The anti-cocaine effects were also examined using self-administration, dose-response and drug-behavioural sensitisation tests. 16-Ethy was tested at 2 mg/kg in all experiments. Results: Acute pre-treatment of 16-Ethy induced sedative effects in non-habituated locomotor activity but when rats were habituated prior to administration, no sedation was observed. In contrast, Sal A (2 mg/kg) had sedative effects in habituated, but not in non-habituated locomotor activity (p = 0.0037). Compared to vehicle-treated rats, 16-Ethy and Sal A did not display pro-depressive effects in the forced swim test, show anxiogenic or aversive properties or modulate behavioural sensitisation to cocaine. Cocaine self-administration and dose-response tests were not successfully completed. Conclusion: At 2 mg/kg, 16-Ethy was found to display sedative effects in non-habituated locomotor activity but not in a habituated paradigm. Compared to vehicle-treated rats, 16-Ethy did not display pro-depressive effects in the forced swim test, or display anxiogenic or aversive properties and did not show significant cocaine sensitisation. Cocaine self-administration and dose-response tests were not successfully completed and will need to be repeated to ascertain the effects of 16-Ethy on them. However, 16-Ethy has shown glimpses of promise as a potential pharmacotherapy against addiction.</p>

Exploring the side effect profile of 16-Ethynyl Salvinorin A

<p>Introduction: Drug addiction is a chronic and relapsing disorder that has widespread socioeconomic and health consequences. Globally, there are over 29.5 million people who are drug dependent, and New Zealand has one of the highest rates of drug use rates in the developed world. Currently, there are no Food and Drug Administration (FDA) approved pharmacotherapies that target psychostimulant addiction. Kappa opioid receptor (KOPr) agonists are being studied as a potential pharmacotherapy as it utilizes the brain’s own mechanism for controlling reward, however, KOPr agonists have unwanted side effects such as dysphoria and sedation. This thesis explores the KOPr agonists Salvinorin A (Sal A), a naturally-occurring, highly potent and short-acting non-nitrogenous KOPr agonist and a structural analogue, 16-Ethynyl Salvinorin A (16-Ethy). KOPr agonists, such as Sal A have known preclinical anti-addictive and anti-reward effects, therefore, this thesis focuses on evaluating Sal A and 16-Ethy in preclinical tests of reward and side effects. Methods: Male Sprague-Dawley rats were used in preclinical tests to evaluate common KOPr-mediated side-effects including anxiety (elevated plus maze), depression (forced swim test) sedation (locomotor activity) and aversion (conditioned place aversion). The anti-cocaine effects were also examined using self-administration, dose-response and drug-behavioural sensitisation tests. 16-Ethy was tested at 2 mg/kg in all experiments. Results: Acute pre-treatment of 16-Ethy induced sedative effects in non-habituated locomotor activity but when rats were habituated prior to administration, no sedation was observed. In contrast, Sal A (2 mg/kg) had sedative effects in habituated, but not in non-habituated locomotor activity (p = 0.0037). Compared to vehicle-treated rats, 16-Ethy and Sal A did not display pro-depressive effects in the forced swim test, show anxiogenic or aversive properties or modulate behavioural sensitisation to cocaine. Cocaine self-administration and dose-response tests were not successfully completed. Conclusion: At 2 mg/kg, 16-Ethy was found to display sedative effects in non-habituated locomotor activity but not in a habituated paradigm. Compared to vehicle-treated rats, 16-Ethy did not display pro-depressive effects in the forced swim test, or display anxiogenic or aversive properties and did not show significant cocaine sensitisation. Cocaine self-administration and dose-response tests were not successfully completed and will need to be repeated to ascertain the effects of 16-Ethy on them. However, 16-Ethy has shown glimpses of promise as a potential pharmacotherapy against addiction.</p>

Evaluation of the antidepressant-like effect of chronic administration of Nigella fixed oil versus fluoxetine in rats

Background: Depression is a group of syndromes characterized by notable and persistent mood disorders, and is one of the most prevalent psychiatric disorders, while the existing treatments have an altered risk-benefit balance. The therapeutic properties of Nigella have been confirmed, suggesting the reliance on phytotherapy. The objective of the present paper is to investigate the antidepressive-like effect of Nigella sativa on rats exposed to the Unpredictable Chronic Mild Stress procedure. Methods: Wistar rats were used to investigate the antidepressive-like effect. The stress procedure used in this study combined many stressful conditions. After 6 weeks of treatment, behavioral test (forced swim test) was conducted, and histological changes of the hippocampus were examined. Results: Treatment by nigella and fluoxetine significantly reduced the struggling time. Conclusion: Histopathological analysis showed that control treatments result in more loosely arranged cells, significant apoptotic neurons characterized by an irregular appearance, and pyknotic hyperchromatic. A reduction of the thickness of the pyramid layer was also observed in the groups treated with nigella and fluoxetine, suggesting that nigella could be used as a treatment or an adjuvant preventing depressive-like disorders.

Evaluation of Additive or Synergistic Effect of Piper nigram and Ocimum sanctum Extracts for their Antidepressant Activity

Depression is a state of excessive sensitivity to criticism, fear of rejections, lack of self-interest, loss of pleasure. In the traditional systems of medicine, many plants and formulations have been used to treat depression for thousands of years. In recent times, research on the plants increased globally and so many plants provide the evidence to cure diseases. Ocimum sanctum, popularly known as Tulsi is one of the sacred herbs for Hindus in the Indian subcontinent. It has a versatile role in traditional medicine. The fruits of Piper nigrum are used to make black pepper. This hotly pungent spice is one of the earliest known and most widely used spices in the world today. Wide range of animal tests for antidepressant agents are commonly used. The Forced swim test and Tail suspension test in mice were mostly used. Hence in the present study Forced swim test was used as animal model of depression. In present study immobility time in Forced swim test was significantly decreased by a combination of Piper nigrum fruit extract and Ocimum sanctum extract treated groups compared to control group. The combination of extracts (50 mg/kg each) activity was comparable to standard drug Fluoxetine. Treatment with extracts does not modify the locomotor activity of mice, which indicates that they exert antidepressant effects without modifying significantly locomotor activity. Therefore, the present study confirms the combination of alcoholic extract of Piper nigrum (AEPN) fruit and aqueous extract of Ocimum sanctum (AEOS) possessing additive/synergistic antidepressant activity.

Study of Antidepressant Activity of Garcinia indica(Kokum) Fruit Rind in Wistar Albino Rats

BACKGROUND Depression is a mental disorder which is treatable but detected less often in primary healthcare settings. Therefore, there is a need for an effective treatment strategy for the management of depression. Garcinia indica (Thouars) Choisy is a slender evergreen tree. An invitro animal study has shown that its phytochemical constituent, hydroxy citric acid has the ability to increase serotonin levels in the brain. Hence, the objective of the study was to evaluate the antidepressant activity of ethanolic extract of Garcinia indica fruit rind in animal models of depression and compare it with control and standard drugs, imipramine, and fluoxetine. METHODS The study was conducted on Wistar albino rats of either sex. The animals were grouped into five, containing six animals in each group. Control (0.1 % carboxymethylcellulose, 10ml/kg), ethanolic extract of Garcinia indica (GIEE1) – 250mg/kg, ethanolic extract of Garcinia indica (GIEE2) – 500mg/kg, Standard1 - Imipramine – 10mg/kg ( Forced Swim test only) and Standard2 - Fluoxetine – 20mg/kg (Tail suspension test only). Drugs were administered for 14 days and antidepressant activity was evaluated on the 14th day after one hour of drug administration using two models - Forced swim test and tail suspension test. Results were tabulated as mean ± SEM (standard error of mean). One-way analysis of variance (ANOVA) followed by Tukey Kramer test was used to interpret the statistical significance. RESULTS The period of immobility was obtained as 21.83 ± 1.44 and14.66 ± 2.74 in forced swim test and 36.8 ± 1.01 and 14.3 ± 0.954 in tail suspension test in GIEE1 and GIEE2 treated groups respectively, which was significantly less compared to control. CONCLUSIONS Garcinia indica has significant antidepressant activity compared to the control. KEY WORDS Antidepressant, Garcinia indica, Fruit Rind, Wistar Albino Rats