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Background: Sensory signals and intrinsic activity of the neuronal circuits deeply influence on developing the sensory systems in early life. Light deprivation of animals is known as an established method in assessment of environmental signals in development of the nervous system. Methods and Materials: In this experimental study eighteen male rats at 75 days of postnatal age were used. The animals were divided in two groups, one reared in a cycle of 12light/12dark (light reared-LR) and the other keep in darkness since birth through experiment (Light deprived- LD). The animals were trained in a Morris water maze for spatial memory. They must navigate the maze until finding a platform hidden 1 cm below of water. Then, the time required and the distance spent to find the platform were measured for assessment of the animal behavior. Each animal was given 4 trials/day and the experiment lasted for 6 days. This stage was followed by probe and postprobe tests to evaluate how the learning is consolidated. Results: The results indicated that, compared to their LD counterparts, the LR group was superior in finding the platform where they required a noticeable shorter time to hit the platform(p<0.009). Also, animals in the LR group steered a shorter distance to find the target than did the LD animals(p<0.034). While the two groups elicited a considerable difference during the first half of the experiment both LR and LD rats demonstrated a similar behavior over the second half of the study. Conclusion: The light deprivation negatively influences the spatial navigation in water maze so that the visually deprived rats show less ability in searching the maze based on the spatial cues.

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Background: Environmental signals have a crucial role in development of brain’s structure and function during critical period of brain development. Gt was valuated the devebpmental effeck in developmental effect of visual deprivation on synaptic plasticity of Dentate Gyrus neurons was evaluated.

Materials and Methods: This experimental study was carried on 2 groups (n=48) rats kept in standard 12-hour light/dark condition (Light Reared-LR) or in complete darkness (Dark Reared-DR) since birth throughout the study. Each group, in turn, was divided into 3 groups of 2, 6 and 10 weeks old subgroup (n=8 for each). Stimulating the perforant path, field potentials were recorded in the Dentate Gyrus area for 30 minutes. Then, the tetanic stimulation was applied to the Schaffer collaterals and the field potentials were pooled for 120 minutes post-tetanus in all animals.

Results: The basic responses of the LR animals decreased and the amplitude of the DR rats increased, across aging. After the LTP induction, amplitude of responses increased in all groups but the amount and stability of them were lower dark reared in animals than the LR ones.

Conclusion: Change in environmental visual signals impairs basic response and LTP induction in neurons of Dentate Gyrus area of hippocampus.

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Abstract

Background: Stress oxidative factors are known to causes diseases resulting from metabolic disorders. Therefore, preventing, or at least decreasing the amount of these factors may have a positive impact on prevention or improvement of the metabolic problems. Recently, the herbal medicines are more considered due to more effectiveness. We designed the present study to evaluate anti-oxidant effect of aqueous extract of lavender (Lavandula angustifolia).

Materials and Methods: For extract preparation, the dry aerial part of lavender mixed with boiling water for 4 hours and then the container was filtered and condensed in a bain marie. Finally, the extract was powdered by freeze dryer. The anti-oxidant activities of the herbal medicine samples in 5, 10, 20 and 40 ppm concentrations were determined via DPPH method. This method is based on free radical scavenging of 2, 2- dipheny L-1-picrylhydrazyl(DPPH) reflected in the color and absorbance changes in spectrophotometery method in 520 nm. Finally the IC50 was calculated and compared with that of for vitamin C as a standard.

Results: All doses of the aqueous extract of the lavender showed dose- dependent potent anti-oxidant activity, So that, their differences were significant compared to control sample. The IC50 of the herbal medicine was 24.66 ppm that was less than the vitamin C of 2.3 ppm.

Conclusion: As a potent anti-oxidant, the lavender aqueous extract can be effective in treatment of metabolic diseases.

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