The effects of oxytocin on cognitive defect caused by chronic restraint stress applied to adolescent rats and on hippocampal VEGF and BDNF levels.

BACKGROUND: Because brain development continues during adolescence, the effects of chronic stress on hippocampal changes that occur during that period are permanent. Oxytocin, which is synthesized in the hypothalamus and has many receptors in brain regions, including the hippocampus, may affect learning-memory. This study aimed to investigate chronic restraint stress on hippocampal functions, and hippocampal vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF) levels in adolescent male and female rats and the role of oxytocin in these effects. MATERIAL/METHODS: Experimental groups included control, stress+oxytocin, and stress+saline groups. Restraint stress was applied to all the stress groups for 1 h/day, for 7 days. Learning-memory tests were performed after the 7th day. RESULTS: In the stress+oxytocin groups, the process of finding the platform was shorter than in others groups. The stress+saline groups spent less time, whereas the stress+oxytocin groups spent more time, on the target quadrant in the probe trial. In the stress+oxytocin groups thigmotaxis time (indicating anxiety) decreased, but VEGF and BDNF levels increased. A positive correlation was found between VEGF and BDNF levels and the time spent within the target quadrant. CONCLUSIONS: The results indicate that impaired hippocampal learning and memory loss due to chronic restraint stress can be positively affected by intranasal oxytocin.

Higher body fat and lower fat-free mass in girls with premature adrenarche.

OBJECTIVE: Idiopathic premature adrenarche (PA) refers to presence of androgenic signs before the age of eight years in girls in the absence of thelarche. In children with PA, increased adrenal androgens lead to changes in body composition and transient growth acceleration. Although the association between PA and some components of the metabolic syndrome is well known, body composition has not been extensively studied in these patients. METHODS: We examined 47 girls with PA with a median age of 7.39 years and 57 healthy controls with a median age of 7.11 years. For PA group, the inclusion criteria were appearance of pubic/axillary hair before 8 years of age, absence of findings of central puberty and absence of use of any medication. Patients with steroidogenic enzyme defects and virilizing tumors were excluded. Height, body weight, waist and hip circumference were measured. The bioelectrical impedance method was used for body composition analysis. RESULTS: In the PA group, both body weight standard deviation score (SDS) and height SDS were significantly higher than in the controls (p<0.001 for both). While total body fat percentage values were significantly higher in the PA group than in the controls (median 22.8% vs. 19.95%, p=0.049), fat-free mass (FFM) and total muscle mass percentages were significantly lower than in the controls (median 76.8% vs. 79.9%, p=0.024 and 72.6% vs. 75.7%, p=0.018, respectively). CONCLUSION: Our findings revealed that girls with PA have higher body weight and height for age values. They also show significant changes in body composition such as an increase in total body fat percentage with a concomitant decrease in the percentages of FFM, muscle mass and total body water.

Serum IGF-1 levels correlate negatively to liver damage in diabetic rats.

Diabetes and insulin resistance frequently cause liver damage. Diabetes also causes reduction in liver and blood IGF-1 levels. We investigated the relation between liver damage and IGF-1 levels in diabetic rats. Fourteen Wistar albino rats were divided into control and diabetic groups. Diabetes was induced by streptozotocin. Rats were sacrificed for biochemical and histologic examinations 2 weeks after streptozotocin injection. Serum and liver IGF-1 levels were decreased, liver malondialdehyde (MDA) levels were increased, glutathione peroxidase (GPx) enzymes activities were decreased and serum alanine aminotransferase (ALT) levels were increased in diabetic group. Microscopic examination of liver revealed that normal tissue organization was disrupted in streptozotocin-induced diabetic rats. There was a strongly positive correlation between blood glucose levels and liver injury, and blood and liver IGF-1 levels. There was a strongly negative correlation between blood IGF-1 levels and hepatic injury. Our results suggest that reduction of blood IGF-1 levels correlates with hepatic injury and circulating IGF-1 levels may have predictive value for determining hepatic damage that results from diabetes. In addition, circulating IGF-1 levels are correlated with glutathione levels and the oxidative stress status of diabetic rat liver.

Maternal treadmill exercise during pregnancy decreases anxiety and increases prefrontal cortex VEGF and BDNF levels of rat pups in early and late periods of life.

In a previous study we demonstrated that, regular aerobic exercise during pregnancy decreased maternal deprivation induced anxiety. The purpose of this study is to investigate whether the positive effects of maternal exercise on the male and female offspring's early and late period of life. Half of the test subjects in each group were evaluated when they were 26 days old, and the other half were evaluated when they were 4 months old. The anxiety levels of maternally exercised groups were less than the control groups in both sexes and in both prepubertal and adult periods. The locomotor activity more increased in females. The prefrontal VEGF and BDNF levels were greater for both age groups and sexes in the maternally exercised group compared to control group. Moreover, there was a strong positive correlations between prefrontal cortex BDNF levels and results of open field tests; and VEGF levels and results of elevated plus maze tests. There was no difference in serum corticosterone levels between groups. These results indicate that maternal exercise during pregnancy may protect the pups from anxiety in early and late periods of life, and affects the prefrontal cortex positively.

Acute footshock-stress increases spatial learning-memory and correlates to increased hippocampal BDNF and VEGF and cell numbers in adolescent male and female rats.

It is well known that the acute-stress enhances cognitive functions in adults, but is not known in adolescents. The purpose of this study is to investigate the effects of low and high intensities of acute-stress on hippocampus and spatial memory in the adolescent male and female rats. Thirty-eight days aged rats were subjected to 0.2 and 1.6 mA intensity of footshock-stress for 20 min. Spatial memory performance was assessed in the Morris water maze. Learning had been positively affected in stress groups. Neuron density in the CA1 hippocampal region and the gyrus dentatus as well as VEGF and BDNF levels of hippocampus increased in all stress groups. In females, learning process and BDNF levels increased in low-intensity-stress group than high-intensity-stress group. There was no difference in hippocampal apoptosis among groups. We conclude that adolescent hippocampus is affected positively from acute-stress; however, while there is no difference in male response with respect to intensity of stress, females are affected more positively from low-intensity of stress.

Maternal exercise decreases maternal deprivation induced anxiety of pups and correlates to increased prefrontal cortex BDNF and VEGF.

Maternal deprivation (MD) may cause neuropsychiatric disorders such as anxiety disorder by negatively affecting the cognitive functions and behavior in pups. The aim of this study is to investigate whether maternal exercise during pregnancy has beneficial effects on anxiety that increases with MD, and on the levels of VEGF and BDNF which have anxiolytic effects on the prefrontal cortex, the anxiety-related region of the brain. The anxiety level in the deprivation group was greater than the control group and found more in male than female pups. The prefrontal cortex VEGF and BDNF levels were decreased in the deprivation group compared to control group while serum corticosterone levels were increased in the deprivation group. Anxiety and serum corticosterone levels were decreased in maternally exercised female and male pups, while the prefrontal cortex VEGF and BDNF levels were increased, compared to sedentary mother's pups. These results indicate that maternal exercise may attenuate the negative effect of stresses such as maternal deprivation that can be encountered early in life.