Animal Models of Depression - Chronic Despair Model (CDM)

Summary

The chronic despair mouse model (CDM) of depression consists of repetitive forced swim sessions and another delayed swim phase as a read-out. It represents a suitable model for induction of a chronic depressive-like state stable for at least 4 weeks, amendable to evaluate subchronic and acute treatment interventions.

Abstract

Major depressive disorder is one of the most prevalent forms of mental illnesses and causes tremendous individual suffering and socioeconomic burden. Despite its importance, current pharmacological treatment is limited, and novel treatment options are urgently needed. One key factor in the search for potential new drugs is evaluating their anti-depressive potency in appropriate animal models. The classical Porsolt forced swim test was used for this purpose for decades to induce and assess a depressive-like state. It consists of two short periods of forced swimming: the first to induce a depressed state and the second on the following day to evaluate the antidepressant effect of the agent given in between the two swim sessions. This model might be suitable as a screening tool for potential antidepressive agents but ignores the delayed onset of action of many antidepressants. The CDM was recently established and represented a modification of the classical test with notable differences. Mice are forced to swim for 5 consecutive days, following the idea that in humans, depression is induced by chronic rather than by acute stress. In a resting period of several days (1-3 weeks), animals develop sustained behavioral despair. The standard read-out method is the measurement of immobility time in an additional delayed swim session, but several alternative methods are proposed to get a broader view of the mood status of the animal. Multiple analysis tools can be used targeting behavioral, molecular, and electrophysiological changes. The depressed phenotype is stable for at least 4 weeks, providing a time window for rapid but also subchronic antidepressant treatment strategies. Furthermore, alterations in the development of a depressive-like state can be addressed using this approach. CDM, therefore, represents a useful tool to better understand depression and to develop novel treatment interventions.

Introduction

Affective disorders, such as major depressive disorder, are among the most frequent and challenging mental illnesses and are associated with high individual suffering¹, an increase of suicide risk², and cause a considerable socioeconomic burden³ for society. Despite its impact, treatment options are limited, and there is an urgent need for the development of novel antidepressive interventions, especially due to the innovation crisis in psychopharmacology over the last decades. In order to understand the pathophysiology of depression and test potential new agents, rational and valid animal models a....

Protocol

All experiments were performed in agreement with European guidelines (EU 2010/63) and in accordance with the German animal protection law (TierSchG), FELASA (www.felasa.eu/guidelines.php), the national animal welfare body GV-SOLAS (www.gv-solas.de/index.html) guide for the care and use of laboratory animals, and were approved by the animal welfare committee of the University of Freiburg and by the Comite d’Ethique en Matiere d’Experimentation Animale de Strasbourg (CREMEAS, CEEA35), as well as local authoriti.......

Discussion

The CDM model represents a relevant and established model for testing the anti-depressive potency of new interventions and opens an extended time window for molecular or electrophysiological experiments to elucidate the pathophysiology of depression. Especially when combined with other tests to assess a depression-like state, CDM has a high face and concept validity. It combines subchronic stress and acquired helplessness for induction and produces a long-lasting depressive-like state. It is insensitive to the single app.......

Materials

Name	Company	Catalog Number	Comments
Beaker, 2000 mL	Kimble Kimax	14000-2000	any vessel >2000ml and diameter of 24-26 cm possible
Digital Thermometer	Hanna Instruments	846-4708	any digital thermometer possible
Digitalwaage 200 g Dipse	DIPSE	tp200	any digital scale possible
Lenovo ThinkCentre V50a-24IMB AiO 11FJ00DVGE - 60,5 cm	Lenovo	A 908278	any standard Personalcomputer possible
Logitech PTZ Pro	Logitech	1000005246	any high resolution camera possible
Stopwatch ROTILABO	Carl Roth	L423.1	any stopwatch possible
Timer ROTILABO	Carl Roth	A802.1	any timer possible