Sex difference affects fear extinction but not lithium efficacy in rats following fear-conditioning with respect to the hippocampal level of BDNF.

In rodents, exposure to electrical shock and creating a strong fear memory using fear-conditioning model can induce PTSD-like behavior. In this study, we induced a fear-conditioning model in rats and investigated freezing (PTSD-like) behavior, 21 days after three shocks exposure (0.6 mA, 3 s, 30 seconds interval) in both male and female rats. Lithium was injected intraperitoneally (100 mg/kg) in three protocols: (1) 1 h after fear-conditioning (2) 1 h, 24 h, and 48 h after fear-conditioning (3), 1 h, 24 h, 48 h, 72 h, and 96 h after fear-conditioning. Extinction training (20 sounds without shocks, 75 dB, 3 s, 30 seconds interval) was performed in three protocols: (1) 1 h after fear-conditioning (one session), (2) 1 h, 24 h, and 48 h after fear-conditioning (three sessions), (3), 1 h, 24 h, 48 h, 72 h, and 96 h after fear-conditioning (five sessions). Forced swim test (FST) and hot plate were used to assess behavior. Results showed that lithium in all protocols had no effect on freezing behavior, FST, and pain subthreshold in all rats. Extinction training decreased freezing behavior, with more efficacy in females. In males, only 5-session training was effective, while in females all protocols were effective. Extinction training also altered pain perception and the results of FST, depending on the sessions and was different in males and females. Brain-derived neurotrophic factor (BDNF) mRNA level was increased in females following 3 and 5 sessions, and in males following 5 sessions extinction training. In conclusion, we suggested that there is a sex difference for the effect of extinction training on freezing behavior and BDNF mRNA level in a rat model of fear-conditioning.

First-episode mania after COVID-19: A case series in Iran.

Background: Increasing reports of manic episodes in patients during acute infection with COVID-19 have been documented since the pandemic began, including individuals without a previous personal or family history of bipolar disorder. As infections and autoimmunity have putative roles in bipolar disorder, we aimed to document the clinical presentations, associated stressors, family aggregation patterns, and brain imaging and electroencephalographic correlates with a series of patients with episodes of mania that emerged shortly after COVID-19 infections. Methods: We obtained all relevant clinical information from 12 patients whose first manic episode started within a month of COVID-19 infection and were treated at Rasool-e-Akram hospital and Iran psychiatric hospital, two tertiary medical centers in Tehran, Iran, in 2021. Results: Patients had a mean age of 44. The interval between the onset of symptoms of COVID and mania ranged between 0 and 28 days (mean: 16.25, median: 14 days); it was observed to be shorter in patients with a family history of mood disorders but not in those receiving corticosteroids. Alongside a descriptive overview of our sample, we provide detailed narrative descriptions of two of the cases for illustrative purposes and discuss our observations in the context of other cases reported elsewhere and the state-of-the-art regarding infectious diseases, COVID-19, and bipolar disorder as reported in previous literature. Conclusion: Our case series documents observational and naturalistic evidence from a dozen of cases of mania in the context of acute COVID-19, which, while limited, calls for analytical research of the phenomenon, and points at a family history of bipolar disorder and the use of corticosteroids as factors for particular focus.