Influence of acute or chronic administration of ovarian hormones on the effects of desipramine in the forced swim test in female rats

Revisiting the antidepressant-like effects of desipramine in male and female adult rats: sex disparities in neurochemical correlates

Background

The preclinical antidepressant-like characterization of desipramine relied almost exclusively in male rodents, with only a few contradictory reports done in females. Given that most experiments assessed a single dose and/or timepoint of analysis after-treatment, this study evaluated potential sex-differences in the length of the antidepressant-like response induced by different doses of desipramine as well as the molecular underpinnings driving the different responses by sex.

Methods

Male and female Sprague–Dawley rats were treated (i.p.) with 3 pulses of desipramine (5, 10 or 20 mg/kg) or vehicle (0.9% NaCl) within 24 h. The antidepressant-like effects were evaluated in the forced-swim test 1-h, 1- and 3-day post-treatment. The rate of cell proliferation and the regulation of key neuroplasticity markers (FADD, Cdk5, p35, p25) involved in antidepressant-like responses in the hippocampus were evaluated 1-h, 1-day and 5-day post-treatment.

Results

Desipramine induced similar antidepressant-like effects in male and female rats (effective doses of 10 and 20 mg/kg, with effects that lasted up to 1-day post-treatment), without altering the rate of cell proliferation. However, some sex-differences emerged when evaluating neuroplasticity markers in the hippocampus, while no changes were observed for female rats, desipramine regulated FADD, Cdk-5 and p25 in males in a way that suggested neuroprotective actions.

Conclusions

Our findings imply that while desipramine induced similar antidepressant-like responses for male and female rats, some differences emerged in the regulation of certain neuroplasticity markers, suggesting that distinctive molecular mechanisms might be participating in the therapeutic response of desipramine for both sexes.

The Impact of Hormonal Contraceptive Use on Serotonergic Neurotransmission and Antidepressant Treatment Response: Results From the NeuroPharm 1 Study

BACKGROUND

Hormonal contraceptive (HC) use has been associated with an increased risk of developing a depressive episode. This might be related to HC's effect on the serotonergic brain system as suggested by recent cross-sectional data from our group, which show that healthy oral contraceptive (OC) users relative to non-users have lower cerebral serotonin 4 receptor (5-HT4R) levels. Here, we determine if cerebral 5-HT4R binding differs between HC non-users, OC users, and hormonal intrauterine device (HIUD) users among women with an untreated depressive episode. Also, we test if antidepressant drug treatment response and its association with pre-treatment 5-HT4R binding depends on HC status.

METHODS

[¹¹C]-SB207145 Positron Emission Tomography imaging data from the NeuroPharm-NP1 Study (NCT02869035) were available from 59 depressed premenopausal women, of which 26 used OCs and 10 used HIUDs. The participants were treated with escitalopram. Treatment response was measured as the relative change in the Hamilton Depression Rating Scale 6 items (rΔHAMD₆) from baseline to week eight. Latent variable models were used to evaluate the association between global 5-HT4R binding and OC and HIUD use as well as rΔHAMD₆.

RESULTS

We found no evidence of a difference in global 5-HT4R binding between depressed HC users and non-users (p≥0.51). A significant crossover interaction (p=0.02) was observed between non-users and OC users in the association between baseline global 5-HT4R binding and week eight rΔHAMD₆; OC users had 3-4% lower binding compared to non-users for every 10% percent less improvement in HAMD₆. Within the groups, we observed a trend towards a positive association in non-users (p_adj=0.10) and a negative association in OC users (p_adj=0.07). We found no strong evidence of a difference in treatment response between the groups (p=0.13).

CONCLUSIONS

We found no difference in 5-HT4R binding between HC users vs. non-users in depressed women, however, it seemed that 5-HT4R settings differed qualitatively in their relation to antidepressant drug treatment response between OC users and non-users. From this we speculate that depressed OC users constitutes a special serotonin subtype of depression, which might have implications for antidepressant drug treatment response.

Identification of the antidepressive properties of C1, a specific inhibitor of Skp2, in mice

We have reported that SMIP004, an inhibitor of S-phase kinase-associated protein 2 (Skp2), displays antidepressant-like activities in stress-naïve and chronically stressed mice. Here, we investigated the antidepressant-like effect of C1, another inhibitor of Skp2, in mouse models following acute or chronic drug administration at different doses and treatment times by using the tail suspension test (TST), forced swimming test (FST), and social interaction test (SIT). The time- and dose-dependent results showed that the antidepressant-like effect of C1 occurred 8 days after the drug treatment, and C1 produced antidepressant-like activities at the dose of 5 and 10 but not 1 mg/kg in male or female mice. C1 administration (5 mg/kg) also induced antidepressant-like effects in stress-naïve mice in a three-times administration mode within 24 h (24, 5, and 1 h before the test) but not in an acute administration mode (1 h before the test). The C1 and fluoxetine co-administration produced additive effect on depression-like behaviors in stress-naïve mice. The antidepressant-like effect of C1 was not associated with the change in locomotor activity, as no increased locomotor activity was observed in different treatment modes. Furthermore, the long-term C1 treatment (5 mg/kg) was found to ameliorate the depression-like behaviors in chronic social defeat stress-exposed mice, suggesting that C1 can produce antidepressant-like actions in stress conditions. Since C1 is a specific inhibitor of Skp2, our results demonstrate that inhibition of Skp2 might be a potential strategy for the treatment of depression, and Skp2 may be potential target for the development of novel antidepressants.

Desipramine, commonly used as a noradrenergic neuroprotectant in 6-OHDA-lesions, leads to local functional changes in the urinary bladder and gastrointestinal tract in healthy rats

The 6-hydroxydopamine (6-OHDA) rat model is one of the most common animal models of Parkinson's disease. When experimentally inducing dopaminergic neurodegeneration in the nigrostriatal pathway using 6-OHDA, the noradrenergic reuptake inhibitor desipramine is often systemically injected in order to protect against damages to the noradrenergic system in the brain. An increasing number of studies are focusing on understanding the pathophysiological changes underlying autonomic non-motor symptoms, in particular urinary bladder and gastrointestinal dysfunctions, of the disease. Several of these studies have investigated the contractile properties and the activation of smooth muscle in the 6-OHDA rat model. Since the injection of desipramine is commonly placed in close proximity to the urinary bladder and gastrointestinal tract, in the current study we wanted to understand if the drug alone has an effect. For this, we have injected a single dose (25 mg/kg) of desipramine either intraperitonially or subcutaneously and investigated smooth muscle contractility in vitro in the urinary bladder, proximal colon and distal ileum four weeks post injection. Our data show that desipramine significantly alters smooth muscle contractility of the urinary bladder and proximal colon in healthy rats. Conclusively, we suggest, based on our data, that desipramine should be omitted when using the 6-OHDA rat model to investigate smooth muscle function in Parkinson's disease research.

Sexually dimorphic responses of rats to fluoxetine in the forced swimming test are unrelated to the function of the serotonin transporter in the brain

Due to the prevalence of depression in women, female rats may be a better models for antidepressant research than males. In male rats, fluoxetine inhibited the serotonin (5-hydroxytryptamine, 5-HT) transporter (SERT) which is reducing the immobility time in the repeated forced swimming test (rFST). The performance of female rats in this test is unknown. In this study, responses of male and female rats in the rFST under chronic treatment with fluoxetine and the function of SERT in their brains were examined. Wistar rats received oral fluoxetine (females: 0, 1, 2.5, or 5 mg kg^-1  day^-1 ; males: 0 or 2.5 mg kg^-1  day^-1 ; in sucrose 10%, 1.5 ml/rat) 1 hr before the test daily for 12 days over the course of the rFST. rFST consisted of a 15 min pretest followed by 5 min sessions of swimming at 1 (test), 7 (retest 1), and 14 (retest 2) days later. SERT functioning was assessed by ex vivo assays of the frontal cortex and hippocampus of rats. Fluoxetine reduced immobility time of males in the rFST while it failed to do so in females. In vitro treatment with fluoxetine inhibited the uptake of 5-HT of both sexes similarly, while in vivo chronic administration of fluoxetine failed to do so. In summary, rats responded to the chronic treatment with fluoxetine in a sexually dimorphic fashion during the rFST despite the functioning of SERT in their brains remaining equally unchanged. Hence, our data suggest that sexually dimorphic responses to fluoxetine in rFST may be unrelated to the function of SERT in rat brains.

Sex Differences in Antidepressant Effect of Sertraline in Transgenic Mouse Models

The main purpose of this study is to explore sex differences in the antidepressant effect of sertraline in genetic knockout or overexpression estrogen-synthesizing enzyme aromatase (Ar) gene mouse models in the forced swim test (FST). Our results demonstrated a significant reduction of depression-like behavior in the mice with overexpression of brain aromatase (Thy1-Ar) compared to sex- and age-matched Ar^+/− mice or wild type control mice. Using HPLC analysis, we also found an association between the brain estrogen-related antidepressive behavior and the regulation of serotonin (5-HT) system. Interestingly, a single dose administration of sertraline (10 mg/kg, i.p.) induced reduction of immobility time was found in all genotypes, except male Ar^+/− mice. While the underlying mechanisms of sex-specific response on antidepressive effect of sertraline remain to be investigated, our data showed that female mice appear to be more sensitive to sertraline-induced changes of 5-HT system than male mice in the prefrontal cortex (PFC) and the hippocampus (HPC). Further investigation of sex-specific effect of brain estrogen on antidepressant is needed.