Preventive Effect of Mebicar and Ginsenoside Rg1 on Neurobehavioral and Immunological Disruptions Caused by Intermittent Unpredictable Stress in Mice.

OBJECTIVES: Ginsenoside Rg1 and mebicar have been reported to have broad efficacy spectrum, including anti-anxiety and anti-stress. These drugs have been used not only for treatment but also for the purpose of increasing resistance from disease. A specific aim of this study was to investigate whether mebicar or ginsenoside Rg1 can prevent physiological changes resulting from intermittent unpredictable stress (IUS). METHODS: Seven week-old Balb/cByJ mice were administered orally with mebicar (10 mg/kg) or ginsenoside Rg1 (10 mg/kg) starting from a week before they were exposed to IUS until the end of the experiment. IUS, which consists of psychological stress and physical fatigue, was set as 3 bouts (24 h/bout) exposure in a 2-week period. RESULTS: IUS caused hyperactivity and anxiety-like behavior, which were not inhibited by mebicar or ginsenoside Rg1. IUS mice treated with mebicar or ginsenoside Rg1 recovered rapidly from anxiety-like behavior induced by the multiplexed stress compared to the mice not orally treated with mebicar or ginsenoside Rg1. Mebicar or ginsenoside Rg1 could not prevent the decrease of brain-derived neurotropic factor by IUS exposure. However, mebicar or ginsenoside Rg1 prevented elevation of serum corticosterone and secretion of proinflammatory cytokines from splenocytes due to IUS exposure. CONCLUSIONS: This study suggests that mebicar or ginsenoside Rg1 may have little preventive effect on neurobehavioral disruption by IUS exposure, but mebicar or ginsenoside Rg1 shortened the lasting duration of the anxiety caused by exposure to a novel environment. The anti-stress effect of mebicar and ginsenoside Rg1 may be restricted in peripheral stress responses.

Differential anxiety-like behavior, HPA responsiveness, and host-resistance in mice with different circling preference.

Relationships between behavioral sidedness and immune responses in previous studies have differed depending on behavior tests and severity of biological stress in mice. It was necessary to elucidate the psychophysiological mediators that connect behavioral sidedness and immune responses. This study investigated interrelationships among anxiety-like behavior, the HPA axis responsiveness, and host-resistance to bacterial infection. Mice that preferred clockwise circling had lower locomotor activities, higher anxiety-like behavior, and faster activation of the HPA axis than mice that preferred counterclockwise circling. A fast activation of the HPA axis was associated with a higher host-resistance to low dose bacterial infection.

A Novel Animal Model Simulating the Beginning of Combat Exposure.

OBJECTIVE: Predator stress, social defeat stress, and fear conditioning animal models have been applied to investigate combat-related posttraumatic stress disorder (PTSD). However, no animal model psychopharmacological studies have investigated prevention of somatization of increased mental stress and fatigue at the beginning of combat exposure. This study utilized a novel animal model simulating the beginning of combat exposure that aided specification of a set of biomarkers. METHODS: Psychological stress was induced by both inescapable electric foot shock and noise stimuli. Physical fatigue was induced by sleep deprivation and forced exercise in a rotating cage. A new device reflecting simultaneous psychological stress and physical fatigue was constructed. The protocol simulating combat exposure was set as 3 rounds of 24-h exposure in a 2-week period, which was specified as intermittent unpredictable stress (IUS). RESULTS: Mice exposed to IUS (IUS mice) had significantly higher serum corticosterone levels (p < 0.05), excessive locomotive activity (p < 0.001), and anxiety-like behavior (p < 0.02) compared to control mice. IUS mice also had significantly higher IFN-γ (p < 0.001) and TNF-α (p < 0.05) levels in the supernatant of splenic T-cell culture compared to control mice. Brain-derived neurotropic factor levels were significantly decreased (p < 0.04) after IUS exposure. CONCLUSION: The proposed animal model of combat exposure reflected cognitive function impairment, behavior disturbance, and altered neuroimmune interactions without any apparent histopathological changes, and this animal model may be more applicable to protective research on war syndrome than combat-related PTSD after war because the hypothalamic-pituitary-adrenal axis has not been blunted.

Effects of combinational prophylactics composed of physostigmine and procyclidine on soman-induced lethality, seizures and brain injuries.

The antidotal, anticonvulsant and neuroprotective effects of physostigmine (PhS) and procyclidine (PC), the combinational prophylactics for organophosphate poisoning, were evaluated. For the investigation of dose-response relationship in rats and guinea pigs, various doses (0-6 mg/kg) of PC in combination with a fixed dose (0.1 mg/kg) of PhS were pretreated subcutaneously 30 min prior to subcutaneous poisoning with soman. Procyclidine in combination with PhS exhibited remarkable synergistic effects in a dose-dependent manner, leading to 1.92-5.07 folds of protection ratio in rats and 3.00-4.70 folds in guinea pigs. On the other hand, a low effect (1.65 fold) was achieved with the traditional antidotes atropine (17.4 mg/kg) plus 2-pralidoxime (30 mg/kg) treated immediately after soman poisoning, compared with a marked protection (5.50 fold) with atropine (17.4 mg/kg) plus HI-6 (125 mg/kg) in unpretreated rats. Noteworthy, the combinational prophylactics greatly potentiated the effect of atropine plus 2-pralidoxime to 6.13 or 12.27 folds and that of atropine plus HI-6 to 12.00 or 21.50 folds with 1.0 or 3.0 mg/kg of PC, respectively. A high dose (100 µg/kg, 1.3×LD(50)) of soman induced severe epileptiform seizures in rats pretreated with HI-6 (125 mg/kg), resulting in brain injuries in discrete brain regions under histopathological examination in 24 h. Interestingly, such seizures and excitotoxic brain injuries were fully prevented by pretreatment with PhS (0.1 mg/kg) and PC (1 mg/kg). Taken together, it is proposed that the prophylactics composed of PhS and PC could be a promising regimen for the prevention of lethality, seizures and brain injuries induced by soman poisoning.