Contributions from estrogen receptor (ER) subtypes (ERα and ERβ) to postpartum anxiogenic and depressive responses remain unresolved in rats. Using the elevated-plus maze (EPM) and forced swim (FS) tests, we confirmed that primiparous rats exhibited anxiogenic and depressive responses 3 weeks postpartum, improved 5 weeks postpartum (EPM), and recovered at 5 (FS) or 10 weeks postpartum (EPM) compared with diestrus nulliparous females. Immunohistochemistry suggested that these behavioral changes were temporally associated with decreased ERα but not ERβ expression in the medial amygdala (MEA). Additionally, ERα expression in the medial preoptic area (MPOA) significantly increased 10 weeks postpartum. Brain-derived neurotrophic factor (BDNF) expression was significantly elevated in the MEA 3 weeks postpartum. BDNF receptor tropomyosin-related kinase expression was significantly elevated in the MEA at 3 and 10 weeks but not at 5 weeks postpartum. The phosphorylation of ERK (pERK)-2 in the MEA, MPOA, and hippocampal CA1 region was significantly elevated 3 and 5 weeks postpartum. The effects of single daily sc injections of the ERα-selective agonist, propyl pyrazoletriol (PPT); ERβ-selective agonist, diarylpropionitrile; 17β-estradiol (E₂); and vehicle for 6 days in primiparous rats were assessed. PPT and E₂ significantly produced anxiolytic and antidepressant actions in the EPM and FS tests but PPT to a lesser degree than E₂ in the EPM test. Diarylpropionitrile affected the EPM test but was not significantly different from vehicle. BDNF expression was significantly increased 3 weeks postpartum by all treatments in the MPOA but not the CA1 and MEA. E₂ and PPT treatment significantly increased tropomyosin-related kinase and pERK1/2 expression in the MEA and MPOA and increased pERK1/2 expression in the CA1. The onset of anxiety- and depression-like behaviors in postpartum rats may be partly caused by a complex estrogen-mediated mechanism; nevertheless, changes in the ERα-related system, likely in the MEA, are predominantly involved.

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Rationale Novel compound with potent antagonistic activity against orexin receptors may be new treatment option for patients with insomnia. Objective The aim was to investigate the efficacy and safety of single oral doses of the dual orexin receptor antagonist TS-142 in patients with insomnia. Methods This multicenter, double-blind, crossover randomized clinical trial included non-elderly patients with insomnia. Patients were randomized to receive single doses of placebo and TS-142 at doses of 5, 10, and 30 mg in one of four different sequences, with a 7-day washout period between treatments. Primary efficacy endpoints were latency to persistent sleep (LPS) and wake time after sleep onset (WASO) measured by polysomnography. Results Twenty-four patients were included (mean age 50.3 ± 10.5 years; mean duration of insomnia 5.71 ± 8.68 years). Least-squares mean differences (95% confidence interval) from placebo in LPS with 5, 10, and 30 mg TS-142 were − 42.38 (− 60.13, − 24.63), − 42.10 (− 60.02, − 24.17), and − 44.68 (− 62.41, − 26.95) minutes, respectively (all p < 0.001). Least-squares mean differences (95% confidence interval) from placebo in WASO with 5, 10, and 30 mg TS-142 were − 27.52 (− 46.90, − 8.14), − 35.44 (− 55.02, − 15.87), and − 54.69 (− 74.16, − 35.23) minutes, respectively (all p < 0.01). Self-reported aspects of sleep initiation and sleep quality, determined using the Leeds Sleep Evaluation Questionnaire (LSEQ), were also improved with TS-142 administration versus placebo. TS-142 was well tolerated; all adverse events were mild or moderate and none were serious. Conclusion Single-dose TS-142 was well tolerated and had clinically relevant effects on objective and subjective sleep parameters in patients with insomnia. Clinical Trial registration JapicCTI173570 (www.clinicaltrials.jp); NCT04573725 (www.clinicaltrials.gov).

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