Effects of Beta; 1-adrenoceptors in the Basolateral Amygdala on Spatial Memory, Passive Avoidance, Long-term Potentiation and Neuronal Arborization in the Hippocampal CA1 Region in Response to Unavoidable Stress

Abstract Norepinephrine in the basolateral amygdala (BLA) plays a pivotal role in mediating the effects of stress on memory functions in the hippocampus, however, the functional contribution of β1-adrenergic receptors on the BLA inputs to the CA1 region of hippocampus and memory function are not well understood. In the present study the role of β1-adrenoreceptor in the BLA on memory, neuronal arborization and long-term potentiation (LTP) in the CA1 region of hippocampus was examined by infusion the β1-adrenoreceptor agonist (Dobutamine; 0.5µl/side) or antagonist (Atenolol; 0.25µL/side) bilaterally into the BLA before foot-shock stress. Passive avoidance test results showed that Step-through latency time was significantly decreased in the stress group rats one, four and seven days after the stress, which intra-BLA injection of Atenolol or Dobutamine before stress couldn't attenuate this reduction. Barnes-maze results revealed that infusion of Dobutamine and Atenolol significantly reduced spatial memory indicators such as increased latency time, the number of errors and the distance traveling to achieve the target hole in the stress group. These learning impairments in stress rats correlated with a reduction of LTP in hippocampal CA1 synapses in-vivo, which infusion of Dobutamine and Atenolol couldn't attenuate the population spike amplitude and mean-field excitatory postsynaptic potentials (fEPSP) slope reduction induced by stress. Also, the Golgi-Cox staining demonstrated that infusion of Atenolol attenuated stress decreased CA1 region dendritic and axonal arborization. These results suggest that β1-adrenergic receptors activation or block seem to exacerbate stress-induced hippocampal memory deficits and this effect is independent of CA1 LTP modulation.

Saffron (Crocus sativus) aqueous extract reverses the hypothalamus-pituitary-adrenal axis activity in rat model of post-traumatic stress disorder

Abstract Crocus sativus L., Iridaceae, has been used worldwide in traditional medicinefor treatment ofsome neurological disorderssuch as depression. Post-traumatic stress disorder is a mental disorder developed in peoplewho experience stressful events. Since stress has been proposed tocause thehypothalamic-pituitary-adrenal axis malfunction in post-traumatic stress disorder patients, this study aimed at investigating the effect of saffron aqueous extract on hypothalamic-pituitary-adrenal axis activity in rats of post-traumatic stress disorder model. Here, Post-traumatic stress disorder animals received an acute electro foot shock; however, 5 min before the stress session, these animals received an intra-cerebral-ventricular (10 µg/rat) infusion of either saffron aqueous extract or saline. Twenty one days later, they were re-exposedto the stress box withoutinducing stress, andthen were examined for their freezing behavior. The impact of stress and saffron aqueous extract on serum corticosterone, corticotrophin releasing hormone gene expression in hypothalamus and glucocorticoid receptor gene expression in pituitary gland werethen evaluated on day 28. Intra-cerebral-ventricular injection of saffron aqueous extract resulted in an increase in serum corticosterone level and reduced symptoms of freezing behavior, and corticotrophin releasing hormone and glucocorticoid receptor gene expression in post-traumatic stress disorder groups.Saffron administration could improve the symptoms of stress-induced post-traumatic stress disorder, possiblythrough the adjustment ofhypothalamic-pituitary-adrenal axis function.

Effect of Intermittent Feeding on Gonadal Function in Male And Female NMRI Mice During Chronic Stress

ABSTRACT Stress can inhibit gonadal activity via Hypothalamus-Pituitary-Gonad (HPG) axis activity suppression. In the present study, effects of intermittent feeding (IF) on gonadal function under stress in male and female mice were evaluated. Twenty eight male and twenty eight female mice's were divided into four groups. The control group received adequate food and water without stress. The second group received four days of electric shock without food deprivation. The third group was deprived of food two hours/day for a week, and the fourth group was deprived of food (2 hours/day for seven consecutive days) and then electric foot shock stress was applied to them for four days. Blood samples were collected from all animals for plasma testosterone, estrogen and/or Interlukin-6 (IL-6) evaluation. The animals' gonads were also removed and fixed for the measure of their weight. Results showed that stress reduces both testosterone and estrogen levels, whereas IF did not change the hormone levels. In addition, stress increases blood IL-6 concentration. The combination of IF and stress, increased the hormone levels in animals. Stress and IF alone had no significant effect on gonadal weight in the male mice, whereas stress decreased gonadal weight in the females. Combination of stress with IF increased gonadal weight in both male and female mice. In conclusion stress showed a negative effect on gonadal function in both animals with more effect on females. Intermittent feeding inhibits the stress effect and even promotes the gonadal function in both sexes. The effect may be due to IL-6 reduction.

Analgesic and anti-inflammatory activities of hydro-alcoholic extract of Lavandula officinalis in mice: possible involvement of the cyclooxygenase type 1 and 2 enzymes

Abstract Lavandula officinalis Chaix, Lamiaceae, extracts can inhibit inflammation and also pain induced by formalin in mice. This study evaluated the effects of L. officinalis hydro-alcoholic extract on pain induced by formalin and also cyclooxygenase (COX) type 1 and 2 activity in mice. To evaluate probable analgesic and anti-inflammatory effects of the extract, flowers were prepared by maceration and extraction in alcohol and their analgesic effects were studied in male mice, using formalin and hot plate tests. The effect of intraperitoneal hydro-alcoholic extracts of L. officinalis (100, 200, 250, 300, 400 and 800 mg/kg), subcutaneous morphine (10 mg/kg), dexamethasone (10 mg/kg; i.p.) and indomethacin (10 mg/kg; i.p.) on formalin induced pain were studied. Our results indicated that administration of the extract (100, 200, 250, 300, 400 and 800 mg/kg; i.p.) has inhibitory effects on inflammation induced by formalin injection into the animals hind paw. Moreover, this inhibitory effect was equal to the effects of morphine, dexamethasone and indomethacin. The extract in100, 200 and 300 mg/kg; significantly reduced heat-induced pain. The extract also reduced COX activity in dose dependent manner, where the inhibitory effect on COX1 activity was 33% and on COX2 activity was 45%. Here for the first time we show that L. officinialis extract can modulate pain and inflammation induced by formalin by inhibition of COX enzymes.