Effects of Restraint Stress and Nitric Oxide Synthase Inhibition on Learning and Strategy Preference in Young Adult Male Rats

Objective: The aim of this study was to investigate the effects of restraint stress and nitric oxide synthase (NOS) inhibition by NωNitro-L-Arginine (LNA) on learning and strategy preference. Material and Methods: Rats were randomly divided into four groups (Saline, Saline+Stress, LNA, LNA+Stress). Stress was applied for one hour in glass cylinders during 13 days. One hour after this stress application, water maze experiments were started. Injections (saline 1 ml/kg or 50 mg/kg LNA) were given 10 minutes before each experiment. The platform was kept visible or hidden (on the 4th, 8th, 12th days) at the same position. On the 13th day the platform was located on the opposite quadrant. Results: Saline groups exhibited significantly better performances (F(1.31)=174.038 p<0.05) at the beginning compared to the NOS inhibited groups. For initial hidden platform days; stress was determined as an impairment factor (F(1.31)=5.190 p=0.012). At the end, acquisition occurred on both visible and hidden platform days for all groups. There was no significant strategy preference difference between the groups.Development of the stress and NOS inhibition impairments were seen, particularly at different periods of the acquisition. Conclusion: NOS inhibition did not worsen restraint stress-induced learning impairments in rats. Lack of effect may be explained by the antidepressive consequences of NOS inhibition

Brain nitric oxide and antioxidant defense are sexually dimorphic and modulated by gonadectomy

This study assessed the effects of gonadectomy on stable metabolites of nitric oxide and major enzymes involved in antioxidant defense in various regions of male and female rat brain. Male and female Sprague Dawley rats were gonadectomized under anesthesia; 3 weeks following surgery rats were decapitated, brains rapidly removed and dissected (cortex, hippocampus, corpus striatum, midbrain and cerebellum); na&iuml;ve animals of each sex were included as controls. Nitrite/nitrate ($NO_2$/$NO_3$) levels, and catalase (CAT) and superoxide dismutase (SOD) activities were determined in tissue homogenates. The results show that female sex hormones affect the parameters studied and indicate that the basal sex differences de-picted do not necessarily result from the primary effects of sexually dimorphic gonadal hormonal influences. The regional variation implies that the observed sex differences in $NO_2$/$NO_3$ levels may be secondary to differences in central neurotransmission systems such as the glutamatergic or the dopaminergic.This study assessed the effects of gonadectomy on stable metabolites of nitric oxide and major enzymes involved in antioxidant defense in various regions of male and female rat brain. Male and female Sprague Dawley rats were gonadectomized under anesthesia; 3 weeks following surgery rats were decapitated, brains rapidly removed and dissected (cortex, hippocampus, corpus striatum, midbrain and cerebellum); na&iuml;ve animals of each sex were included as controls. Nitrite/nitrate ($NO_2$/$NO_3$) levels, and catalase (CAT) and superoxide dismutase (SOD) activities were determined in tissue homogenates. The results show that female sex hormones affect the parameters studied and indicate that the basal sex differences de-picted do not necessarily result from the primary effects of sexually dimorphic gonadal hormonal influences. The regional variation implies that the observed sex differences in $NO_2$/$NO_3$ levels may be secondary to differences in central neurotransmission systems such as the glutamatergic or the dopaminergic

Examination of empathy-like behaviour in nicotine-preferring rat lines

Aim: Addiction is an important global health issue, impacting also addicts environment and society. Empathy plays crucial role in establishing successful social relationships and is a fundamental component of social life. The aim of this study is to investigate how nicotine preferring (NP) strain and oral forced nicotine administration affects empathy-like behaviour in rats, with gender differences. Materials and Methods: Sprague-Dawley NP rats (10 males/10 females) and wild-type control rats (10 males/10 females) were used. Behavioural tests were administered to all rats before and after oral forced nicotine administration. The behavioural tests were completed in the fourth week of nicotine administration. Anxiety levels that could affect empathy-like behaviour were evaluated with open field, elevated plus maze tests and with blood cortisol levels. Oxytocin receptor and arginine vasopressin (AVP) levels, which have been shown to be related to empathy-like behaviour, were examined in the prefrontal cortex and amygdala regions using the enzyme-linked immunoassay method. Results: It was observed that males from the NP strain showed less empathy-like behaviour than all other groups, and nicotine administration did not cause a significant change in the results. Higher levels of locomotor activity (LA) were found in control females than in all other groups. Blood nicotine and corticosterone levels were higher in NP rats. No significant differences were found in AVP and oxytocin receptor levels in the prefrontal cortex and amygdala. Conclusions: It was found that coming from an addicted strain particularly reduces empathy-like behaviour in males