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ABSTRACT: The aim of this study was to evaluate the effect of intra-hippocampal injection of Growth Hormone (GH) on impaired spatial cognition in rats with Alzheimer’s Disease (AD). Growth hormone replacement therapy leading to improved cognition and well-being has mainly been carried in GH-deficient patients. Neverthelss, relatively only a few studies have investigated the function of GH in the brain. Aged Wistar male rats (350-400 g, 18-20 months old) were randomly divided into 6 groups (7 in each): Control (healthy aged); L; L+Veh; L+GH10; L+GH20 and L+GH40. Rats with AD-like cognitive deficiency was induced by injection of ibotenic acid into Nucleus Basalis of Meynert (NBM) bilaterally (5 μg 0.5 μL<sup>-1</sup>, each side). A guide cannula was implanted in the right hippocampus under stereotaxic surgery for injection of human recombinant GH (10, 20 and 40 μg 2 μL<sup>-1</sup>, during 5 min, twice daily, 9:00 am and 3:00 pm, for 7 days). All rats were trained in Morris water maze to evaluate the spatial learning and memory. Escape latency, traveled distance to find hidden platform and percent time spent in gaol qudrant did not differ between L and L+Veh groups, while latency and distance were reduced significantly. But percent time spent in gaol quadrant (without hidden platform) was increased significantly in NBM-lesioned rats treated with GH (L+GH groups) dose dependently to compare with vehicle treated group. These results suggest that intra-hippocampal injection of GH to aged rats with dementia type of AD (with NBM lesioned) could improve spatial cognition.
Pakistan Journal of Biological Sciences. 01/2009;
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ABSTRACT: This study was conducted to investigate the neuroprotective effects of progesterone (PROG) on electrophysiological and histomorphometrical alternation in STZ-induced diabetic neuropathy starting from 4 weeks after the diabetic induction. Thirty adult male Sprague-Dawley rats were randomly divided into 3 groups (with 10 rats in each), control (nondiabetic), untreated diabetic and diabetic PROG-treated. Diabetes was induced in adult male rats by a single dose injection of streptozotocin (STZ, 55 mg kg<sup>-1</sup>, i.p.). In the PROG-treated group, 4 weeks after induce of diabetes; rats were treated with PROG (8 mg kg<sup>-1</sup>, i.p., every two days) for 6 weeks. Diabetic rats showed a significant reduction in motor nerve conduction velocity (MNCV), mean myelinated fibers (MFs) diameter, axon diameter and myelin sheath thickness in the sciatic nerve after 6 weeks. In the untreated diabetic group endoneurial edema was observed in sciatic nerve and the numbers of MFs with infolding into the axoplasm, irregularity of fibers, myelin sheath with unclear boundaries and alteration in myelin compaction were also increased. Long-term treatment with PROG increased MNCV significantly and prevented all these abnormalities in treated diabetic rats. Our findings indicated that PROG as a therapeutic approach can protect neurophysiologic and histomorphologic alterations induced by peripheral diabetic neuropathy.
Pakistan Journal of Biological Sciences. 01/2008;
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ABSTRACT: Background: Environmental noise is a known stressful factor,that induces alterations of various physiological responses in the exposed individuals. Extensive evidences from animal and human studies have indicated that stress influences cognitive functions. Studies have shown that chronic exposure to noise during pregnancy impairs neurobehavioral and reproductive functions and also reduces the body weight of the offspring. It seems that prenatal noise stress during last three months of fetal life damages the neurons in special areas of brain involved in cognition and impairs the activity of hypothalamuspituitary- adrenal (HPA) axis. It is known very little about the effect of prenatal noise stress on learning. The aim of present work was to determine the effect of prenatal chronic intermittent noise stress on learning in rats. Methods: Fifteen Wistar pregnant rats were exposed chronically to intermittent white noise (90-120dB, 350Hz) during the last two weeks of their pregnancy periods (dark cycle, 07:00Pm-07:00Am). Stressed and nonstressed puppies bred under normal condition up to 3 months of age. Both stressed and nonstressed adult male and female rats were trained in an equal 3 arms Y-maze with 20-25 Volts D.C. electrical footshock and a 12 Watts light stimuli as an active avoidance learning. Animals were trained one session daily and criterion condition response (CCR) was 90 percent of last session of training. Results: Data showed that chronic exposure to noise during pregnancy impairs learning of stressed male rats significantly at all sessions (P<0.01). However, in the stressed female rats the response was decreased significantly only at the first two sessions (P<0.05). Conclusion: The results indicate that prenatal noise stress may damage the neurons in special areas of brain such as hippocampus and alters cognition and behavioral functions. Keywords: noise stress, pregnancy, learning, rat.
Journal of Research in Medical Sciences. 01/2004;
