Effects of haloperidol inhalation on MK-801- and memantine-induced locomotion in mice

Sex differences in the anticompulsive-like effect of memantine: Involvement of nitric oxide pathway but not AMPA receptors

Memantine, an N-Methyl-D-Aspartate (NMDA) antagonist, has been examined as a potential treatment for Obsessive-Compulsive Disorder (OCD). Yet, there is limited knowledge regarding how it works to reduce compulsive behaviour and whether it has different effects on individuals based on their sex. Herein, we investigated if there are sex differences in the anticompulsive-like effect of memantine in adult Swiss mice. Additionally, we explored whether the nitric oxide (NO) pathway and α-amino-3-hydroxy-5-methyl-4-isoazolepropionic acid (AMPA) receptors play a role in memantine's effects. To start, we assessed the impact of a single intraperitoneal dose of memantine (at 3, 5, and 10 mg/kg) on behaviours exhibited in the open field test (OFT) and the marble-burying test (MBT), the latter being a predictive test for anticompulsive effects. All doses of memantine reduced marble-burying behaviour in both male and female mice without affecting their locomotor activity in the OFT. This anticompulsive-like effect was also confirmed in another predictive test, the nest-building test, with the highest memantine dose (10 mg/kg) reducing nest-building behaviour without significant differences between male and female mice. We observed that pre-treatment with L-arginine, a NO precursor, mitigated the anticompulsive-like effect of memantine in male mice but had no effect in female mice in the MBT. Finally, NBQX, an AMPA receptor antagonist, did not block the anticompulsive-like effect of memantine. In summary, our study suggests that the anticompulsive-like effect of memantine does not appear to be sex-specific, does not depend on AMPA receptors, and involves the NO pathway primarily in male mice.

Vortioxetine improved negative and cognitive symptoms of schizophrenia in subchronic MK-801 model in rats

Schizophrenia is a devastating psychiatric disorder with complex symptoms and neurobiology. Serotonergic dysregulation is known to contribute to the pathogenesis of schizophrenia although dopaminergic and glutamatergic systems are thought to have central roles in neurobiology. No significant success can be achieved in the treatment of negative and cognitive symptoms while positive symptoms can be significantly reduced with current pharmacotherapy. Vortioxetine is a new multimodal antidepressant with 5-HT1A agonism, 5-HT1B partial agonism, 5-HT3, 5-HT7, and 5-HT1D antagonism, and serotonin reuptake inhibition. A limited number of studies suggest its therapeutic effect on the negative and cognitive symptoms of schizophrenia. Therefore, we investigated the potential beneficial effects of vortioxetine on behavioral and molecular deficits in the MK-801 model of schizophrenia in rats. Female Wistar albino rats (10-12 weeks) were grouped as saline, MK-801 (0.2 mg/kg), MK-801 + vortioxetine (2.5 mg/kg), MK-801 + vortioxetine (5 mg/kg), MK-801 + vortioxetine (10 mg/kg), MK-801 + risperidone (0.3 mg/kg), MK-801 + haloperidol (1 mg/kg) (n = 8 in each group). MK-801 has been daily administered (i.p.) for 14 days. Vortioxetine and antipsychotic treatments were injected for 21 days after a washout period of MK-801 and locomotor activity (LA), social interaction (SI), novel object recognition (NOR), Y-maze and prepulse inhibition (PPI) tests were performed at the 16-20th days of treatments, respectively. ELISA test was conducted to evaluate molecular analyses. MK-801 decreased PPI (%), social behaviors, and discrimination index in NOR and alternation (%) in the Y-maze test. In NOR and Y-maze tests, especially vortioxetine 5 and 10 mg/kg increased discrimination index and alternation (%) compared to MK-801. In addition, vortioxetine administration increased social behaviors. Moreover, MK-801 decreased GAD67 and parvalbumin levels while vortioxetine increased these protein levels compared to MK-801. Herein, we first suggested a potential therapeutic effect of vortioxetine, a new multimodal antidepressant, on negative and cognitive symptoms and neurobiological deficits including GAD67 and parvalbumin low expression in the MK-801 model in rats. It would be beneficial to confirm our results in different rodent models and to shed light on the possible mechanisms underlying these effects.