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Oxytocin (OT) is considered beneficial to mental health owing to its anxiolytic, prosocial, and anti-stress effects; however, the adverse effects of OT have been controversial, such as its potentially anxiogenic actions. Although OT influences drug abuse and reciprocally affects vulnerability to drug use, the relationship between OT's anxiogenic working and nicotine preference intake has not been clearly defined. To clarify this issue, the effect of acute peripheral administration of OT on anxiety and nicotine preference was investigated in juvenile male rats. Anxiogenic behaviors were noticeably increased in OT-administrated rats, with an increase in serum corticosterone levels. Moreover, increased anxiety-like behaviors and corticosterone levels were observed in the OT analog carbetocin-injected rats. In the nicotine preference test, the rats' aversive responses to initial nicotine choice and preference were not significantly different between saline-injected and OT-injected rats. However, when administered with OT, there was a significant negative correlation between anxiety-like behavior and low-dose nicotine consumption. Collectively, these results provide evidence that acute OT exposure could induce anxiogenic behavior with corticosterone augmentation, contributing to the attenuation of nicotine preference. This suggests that both aspects of OT, as well as their benefits and drawbacks, should be considered. [ABSTRACT FROM AUTHOR]

• Dexmedetomidine accelerated the fear memory extinction. • Dexmedetomidine reduced anxiety behavior. • It was more effective in female rats than in male rats. • Sex-specific effects of dexmedetomidine should be considered. Exposure to stressful stimuli, including fear and anxiety, modulates the central noradrenergic system. Dexmedetomidine is a commonly used α2-adrenoreceptor agonist. Because the effect of fear acquisition varies between sexes, the present study was designed to investigate sex-related differences in the effects of dexmedetomidine on fear memory and anxiety-like behavior. We conducted a fear test and an elevated plus maze test in 6–8-week-old male and female rats. Two doses of dexmedetomidine (20 and 40 μg/kg) were injected intraperitoneally three times at 24 h intervals after the tests: after fear expression, extinction 1, and extinction 2. The repeated administration of dexmedetomidine showed significant acceleration of fear memory extinction in female rats but not in male rats; the effect increased proportionally to concentrations of dexmedetomidine. Compared to male rats, female rats treated with both concentrations of dexmedetomidine showed significant anxiolytic behavior after 1 week. Dexmedetomidine accelerated the fear memory extinction and reduced anxiety; it was more effective in female rats than in male rats. Our results suggest that dexmedetomidine may exert protective effects against fear-related and anxiety-like behaviors in rats with fear memory after repeated administration, and the sex-specific effects of dexmedetomidine should be considered. [ABSTRACT FROM AUTHOR]

Objective: To evaluate predictive values of sarcopenia and visceral obesity measured from preoperative CT/MRIs for postoperative pancreatic fistula (POPF) after pancreaticoduodenectomy in patients with periampullary malignancies.Methods: From the prospectively constructed surgical registry, we included adult patients treated with pancreaticoduodenectomy. Based on CT/MRIs, body morphometric analysis was performed to evaluate the visceral obesity and sarcopenia, based on the areas of visceral fat and skeletal muscle measured at the L3 vertebrae level. We retrieved various perioperative factors from registry. As outcomes of postoperative complications, we evaluated POPF and major complications based on the Clavien-Dindo classification. Multivariate logistic regression analyses were performed.Results: From a total of 284 patients (163 males, 121 females) who met the inclusion/exclusion criteria, POPF, major complications, and 60-day mortality occurred in 52 (18.3%), 34 (12.0%), and 6 (2.1%), respectively. Sarcopenia and visceral obesity were noted in 123 (75.5%) and 66 (40.5%) of men and 68 (56.2%) and 53 (43.8%) of women, respectively. Combination of sarcopenia and obesity (sarcopenic obesity) was noted in 31.9% (52/163) of men and in 26.4% (32/121) of women. In multivariate logistic regression analyses, sarcopenic obesity was the only independent predictor for POPF (OR 2.65, 95% CI 1.43-4.93), and the vascular resection during pancreaticoduodenectomy was the only independent predictor for severe complications (OR 3.75, 95% CI 1.61-8.70).Conclusion: Sarcopenic obesity might be highly predictive for POPF. Body morphometric analysis in preoperative CT/MRI combined with assessment of perioperative clinical features may help to identify high-risk patients and determine perioperative management strategies.Key Points: • Sarcopenic obesity might be predictive for postoperative pancreatic fistula after pancreaticoduodenectomy. • The vascular resection during pancreaticoduodenectomy might be predictive of major complications. • Body morphometric analysis might be helpful for identifying high-risk patients. [ABSTRACT FROM AUTHOR]

Rationale: Tobacco smoking occurs in a wide array of social circumstances. Social support for quitting is generally used to stop smoking, while peer interactions may be a crucial factor in triggering tobacco use among adolescents. Objectives: To determine the role of social factors on nicotine dependence, we compared single- and pair-housed rats subjected to voluntary oral nicotine consumption tests. Methods: Six-week-old adolescent rats were subjected to experimental procedures and assigned to one of the following groups: a male single group, a male pair group with a sibling, a female single group, and a female pair group with a sibling. To measure voluntary nicotine intake, we adopted a two-bottle free-choice paradigm for each two days using 25 μg/ml and 100 μg/ml nicotine solution. Results: There were no differences in change in body weight or food intake between the two groups of either sex. Pair-housed female rats showed a reduction in nicotine consumption and preference for both low- and high-dose nicotine solution, while pair-housed male rats showed only reduced consumption and preference for high-dose nicotine solution, but not low-dose solution, as compared to single-housed male rats. Conclusions: Nicotine consumption is sex-dependently controlled by the social circumstances of rats. This study broadens our perspectives on the role of social interactions as a therapeutic strategy to treat nicotine addiction-related behaviors depending on sex. [ABSTRACT FROM AUTHOR]

Initial tobacco use is initiated with rewarding and aversive properties of nicotine and aversive response to nicotine plays a critical role in nicotine dependency. Decrease of nicotine aversion increases the nicotine use that causes behavioral and neuronal changes of animals. Oxytocin influences drug abuse and reciprocally affect vulnerability to drug use. To assess the effect of oxytocin on initial nicotine aversion and anxiety, we examined voluntary oral nicotine intake and anxiety-like behavior following oxytocin treatment in adolescent rats. Sprague-Dawley male rats (4 weeks old) were used. For oxytocin administration, rats were injected subcutaneously with saline or oxytocin (0.01, 0.1 and 1 mg/kg) according to the assigned groups. Voluntary oral nicotine consumption test was performed by two bottle free-choice paradigm. To examine anxiety-like behavior in rats, we performed a light/dark box test. Oxytocin not only significantly increased the nicotine intake but also alleviated nicotine aversion after acclimation to nicotine solution in a concentration dependent manner. Meanwhile, oxytocin significantly reduced anxiety-like behavior. We suggest that oxytocin itself mitigates aversive response toward initial nicotine intake and anxiety-like behavior. These results widen the psychophysiological perspective on oxytocin for better understanding of nicotine addiction related behaviors influenced by diverse social factors. [ABSTRACT FROM AUTHOR]

We demonstrate the synthesis of Ag nanoparticles (NPs) with diameters in the range 10–20 nm using two phytochemicals, gallic acid and protocatechuic acid, which have similar chemical structures but subtle differences in their chemical potentials. This subtlety in their potential difference improves the control over the reduction of Ag precursors such that their composition and concentration are optimized for both the nucleation and growth steps of NP synthesis. Both steps were carefully monitored using UV–vis spectrophotometry and electron microscopy. The surface interaction energy of the phytochemicals on the NPs was characterized using computational simulation, and electrochemical analysis was performed to calculate the chemical reducibility of the phytochemicals to Ag + ions by cyclic voltammetry. A plausible mechanism of size control was suggested. This novel and valuable method to control the size and the size distribution of Ag NPs enables new applications in materials science, biomedical science, and chemical sensor development. [ABSTRACT FROM AUTHOR]

Social buffering is the phenomenon, in which stress and fear reactions caused by exposure to stressful stimuli when animals are exposed to homogeneous relationships are attenuated. Social buffering reduces fear memory behavior such as escape, avoidance, and freezing behavior in rodents due to social existence. Here, we aimed to determine alterations of fear behavior and neural activity in the medial prefrontal cortex (mPFC) in response to the presence of another rat in fear-exposed conditions and to confirm the role of oxytocin in mPFC in regulating social buffering. We performed a passive avoidance test and determined positive c-Fos expression in single- and pair-exposed rats. Anisomycin (a protein synthesis inhibitor) and oxytocin receptor regulators (carbetocin; agonist and atosiban; antagonist) were microinjected into the mPFC to clarify the role of oxytocin in the mPFC. While single-exposed rats showed a significant increase in both freezing and passive avoidance behaviors compared to control rats, pair-exposed rats showed significantly less fear behavior compared to single-exposed rats. The c-Fos expression in the prelimbic (PL) mPFC was significantly increased in pair-exposed rats compared to that in control and single-exposed rats. The pair-exposed effect was blocked by anisomycin injections into the PL mPFC of pair-exposed rats. Furthermore, when a carbetocin was injected into the PL mPFC in single-exposed rats, fear behavior was decreased, and these changes were blocked by atosiban. Our findings suggest that reduction of fear-related behavior induced by acute pair-exposure is mediated by oxytocin receptors in the PL mPFC. Pair exposure with conspecifics during fear-inducing situations helps coping with fear by significantly increasing the role of oxytocin in the PL mPFC. • Socially paired rats show less fear during fear-conditioning than single ones. • In paired rats, medial prefrontal cortex (mPFC) c-Fos expression is increased. • Fear reduction in paired rats is blocked by a protein synthesis inhibitor. • Fear reduction is induced by mPFC infusion of the oxytocin receptor agonist carbetocin. • Fear reduction in paired rats is blocked by the oxytocin receptor antagonist atosiban. [ABSTRACT FROM AUTHOR]

The kinematic and isotropic hardening behavior was investigated for high and medium entropy alloys with a single-phase face-centered cubic (FCC) structure. The cross-slip associated with screw dislocations in FCC structures is strongly influenced by local fluctuations in the spatial distribution of different atom species. The local atomic arrangements inhibit the movement of Shockley partial dislocations during plastic deformation, thereby lowering the probability of cross-slip and generating a higher back-stress. This study used a solid-solution induced back-stress model, which combines nonlinear kinematic and isotropic hardening, to investigate the effects of dislocation forest stress and back-stress in a non-equiatomic Cr 12 Fe 42 Mn 24 Ni 22 medium entropy alloy. Based on the experimental results, numerical simulations by the finite element method were performed to validate this modeling approach. [ABSTRACT FROM AUTHOR]