ABSTRACT
Postnatal hypoxia is a main cause of neuronal damage in newborn. However, our understanding of the possible preventive or therapeutic methods to reduce the harmful effects of hypoxia is still primary. Pregnant rats were provided with running wheels during their pregnancy. On PND4 [postnatal day 4] to PND8, the rat pups were exposed to postnatal chronic hypoxia [11% O[2], 89% N[2]] in an air-tight plastic chamber for a period of six hours per day. The number of neurons and also angiogenesis in hippocampus were studied. Postnatal exposure to mild hypoxia decreased the number of the neurons in all studied regions of the hippocampus CA1, CA3 [cornu ammonis], DG [dentate gyrus] and SUB [cubiculum] in rat pups. In other words the number of the neurons in rat pups born from voluntary exercise group was not significantly less than control group in CA1, CA3 and DG regions. So maternal Voluntary exercise during pregnancy increases the blood vessel density in the DG region of the hippocampus of the rat pups. In this study for the first time we provide evidences that show the protective effect of maternal voluntary exercise during pregnancy on rat offspring against postnatal hypoxia. We revealed that maternal exercise during pregnancy increases the hippocampal neuron number and angiogenesis in offspring
ABSTRACT
The beneficial effects of physical activity and exercise on brain functions such as improvement in learning and memory are well documented. In a recent study, we have found that blockade of beta-adrenergic receptors by propranolol attenuates an improvement of learning and memory by exercise. However, the anatomical sites of propranolol actions are not known. The aim of this study was to determine the role of Basolateral amygdala [BLA] in the inhibitory effects of propranolol on the beneficial effects of exercise on learning and memory. In order to block the beta-adrenergic receptors, male mice were received the beta-antagonist propranolol [10 mg/kg], before each night of five consecutive nights of exercise. The BLA lesion was made by electrolytic lesion [2mA, 2 s]. Learning and memory were tested on the Morris water maze task using a two-trials-per-day for five consecutive days. A probe trial was performed two days after the last training day. Our results showed that propranolol reversed the exercise-induced improvement in learning and memory in rat. This effect was not blocked by the BLA lesion. However, lesion of the BLA alone blocked exercise-induced enhancement of learning and memory. These findings indicate beta-adrenergic receptors located outside the BLA may mediate the effects of exercise on learning and memory. Also, the BLA play an important role in the mediating the effects of physical activity on learning and memory