role of GABAB receptors in morphine self-administration

There is only little information about the effects of GABA receptors agonist and antagonist on morphine self-administration. Present study was designed to assess role of GABAB receptors in the regulation of morphine-reinforced self-administration. This study was performed in four groups of rats: [1] Saline group, which received saline in the self-administration session. [2] Morphine group, which received morphine in saline solution in the self-administration session. [3] Baclofen + Morphine group, which received both baclofen 20 min before self- administration test and morphine in the self-administration session. [4] Phaclofen + Morphine group, which received both phaclofen 20 min before self- administration test and morphine in the self-administration session. The number of lever pressing and self-infusion were recorded. Morphine significantly increased the number of active lever pressing dose dependently in self-administration session in comparative with saline group. Administration of baclofen, 20 min before morphine self-administration produced significant decrease in the initiation of morphine self-administration during all session. Conversely, pre-treatment of phaclofen increased the number of active lever pressing and self-infusion in this test. Our results indicated a short-term treatment by baclofen, reduced morphine-maintenance response in a dose-dependent manner, suggesting that GABAB receptor agonists could be useful for reversing the neuroadaptations related to opiates

effect of treadmill running on passive avoidance learning in animal model of Alzheimer disease

Alzheimer's disease was known as a progressive neurodegenerative disorder in the elderly and is characterized by dementia and severe neuronal loss in the some regions of brain such as nucleus basalis magnocellularis. It plays an important role in the brain functions such as learning and memory. Loss of cholinergic neurons of nucleus basalis magnocellularis by ibotenic acid can commonly be regarded as a suitable model of Alzheimer's disease. Previous studies reported that exercise training may slow down the onset and progression of memory deficit in neurodegenerative disorders. This research investigates the effects of treadmill running on acquisition and retention time of passive avoidance deficits induced by ibotenic acid nucleus basalis magnocellularis lesion. Male Wistar rats were randomly selected and divided into five groups as follows: Control, sham, Alzheimer, exercise before Alzheimer, and exercise groups. Treadmill running had a 21 day period and Alzheimer was induced by 5 micro g/ micro l bilateral injection of ibotenic acid in nucleus basalis magnocellularis. Our results showed that ibotenic acid lesions significantly impaired passive avoidance acquisition [P < 0.01] and retention [P < 0.001] performance, while treadmill running exercise significantly [P < 0.001] improved passive avoidance learning in NBM-lesion rats. Treadmill running has a potential role in the prevention of learning and memory impairments in NBM-lesion rats