Behavioural Models for the Characterisation of Established and Innovative Antidepressant Agents

The clinical implications of mouse models of enhanced anxiety

Mice are increasingly overtaking the rat model organism in important aspects of anxiety research, including drug development. However, translating the results obtained in mouse studies into information that can be applied in clinics remains challenging. One reason may be that most of the studies so far have used animals displaying 'normal' anxiety rather than 'psychopathological' animal models with abnormal (elevated) anxiety, which more closely reflect core features and sensitivities to therapeutic interventions of human anxiety disorders, and which would, thus, narrow the translational gap. Here, we discuss manipulations aimed at persistently enhancing anxiety-related behavior in the laboratory mouse using phenotypic selection, genetic techniques and/or environmental manipulations. It is hoped that such models with enhanced construct validity will provide improved ways of studying the neurobiology and treatment of pathological anxiety. Examples of findings from mouse models of enhanced anxiety-related behavior will be discussed, as well as their relation to findings in anxiety disorder patients regarding neuroanatomy, neurobiology, genetic involvement and epigenetic modifications. Finally, we highlight novel targets for potential anxiolytic pharmacotherapeutics that have been established with the help of research involving mice. Since the use of psychopathological mouse models is only just beginning to increase, it is still unclear as to the extent to which such approaches will enhance the success rate of drug development in translating identified therapeutic targets into clinical trials and, thus, helping to introduce the next anxiolytic class of drugs.

What's wrong with my mouse model?

Stress plays a key role in pathogenesis of anxiety and depression. Animal models of these disorders are widely used in behavioral neuroscience to explore stress-evoked brain abnormalities, screen anxiolytic/antidepressant drugs and establish behavioral phenotypes of gene-targeted or transgenic animals. Here we discuss the current situation with these experimental models, and critically evaluate the state of the art in this field. Noting a deficit of fresh ideas and especially new paradigms for animal anxiety and depression models, we review existing challenges and outline important directions for further research in this field.

Alleviation of thermoregulatory dysfunction with the new serotonin and norepinephrine reuptake inhibitor desvenlafaxine succinate in ovariectomized rodent models

Hot flushes and night sweats, referred to as vasomotor symptoms (VMS), are presumed to be a result of declining hormone levels and are the principal menopausal symptoms for which women seek medical treatment. To date, estrogens and/or some progestins are the most effective therapeutics for alleviating VMS; however, these therapies may not be appropriate for all women. Therefore, nonhormonal therapies are being evaluated. The present study investigated a new reuptake inhibitor, desvenlafaxine succinate (DVS), in animal models of temperature dysfunction. Both models used are based on measuring changes in tail-skin temperature (TST) in ovariectomized (OVX) rats. The first relies on naloxone-induced withdrawal in morphine-dependent (MD) OVX rats, resulting in an acute rise in TST. The second depends on an OVX-induced loss of TST decreases during the dark phase as measured by telemetry. An initial evaluation demonstrated abatement of the rise in TST with long-term administration of ethinyl estradiol or with a single oral dose of DVS (130 mg/kg) in the MD model. Further evaluation showed that orally administered DVS acutely and dose dependently (10-100 mg/kg) abated a naloxone-induced rise in TST of MD rats and alleviated OVX-induced temperature dysfunction in the telemetry model. Oral administration of DVS to OVX rats caused significant increases in serotonin and norepinephrine levels in the preoptic area of the hypothalamus, a key region of the brain involved in temperature regulation. These preclinical studies provide evidence that DVS directly impacts thermoregulatory dysfunction in OVX rats and may have utility in alleviating VMS associated with menopause.