ABSTRACT
For studying the role of CRF in the process of depression, chronic intra-cerebral ventricular administration of CRF in normal rats for 21 days were performed and compared with the depression model of chronic unpredictable miled stress (CUMS) in rats. The Open-field Test and Morris water Maze were employed to test the ability of locomotion and learning and memory. HPLC-UV, RT-PCR were employed to analyze the level of blood serum cortisol and the expression of CRF as well as its receptors (R1 and R2) of CUMS models. After chronic stress, the locomotion activity and spatial learning and memory ability decreased obviously, while the level of serum cortisol increased evidently, and the CRF and its receptor-1 mRNA levels were higher compared with those in normal rats. The rats with chronic administration of CRF also consistently decreased the weight gain, locomotion activity and the ability of spatial learning and memory as the CUMS model. This work demonstrates that CRF plays a very important role in the depression genesis and development, sustained elevation of CRF induced by stress may be the chief factor for depression.
Subject(s)
Corticotropin-Releasing Hormone/therapeutic use , Depression/drug therapy , Hypothalamo-Hypophyseal System/drug effects , Maze Learning/drug effects , Motor Activity/drug effects , Pituitary-Adrenal System/drug effects , Animals , Brain-Derived Neurotrophic Factor/pharmacology , Corticotropin-Releasing Hormone/pharmacology , Depression/physiopathology , Disease Models, Animal , Male , Maze Learning/classification , Maze Learning/physiology , Motor Activity/physiology , Rats , Rats, Sprague-Dawley , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
The present study was performed to explore learning and memory ability in the depression models of rats. The chronic unpredictable stress and olfactory bulbectomy model of rats were adopted. Open-field test was used to detect the locomotion activity and HPLC-UV was employed to analyze the level of blood serum cortisol. The method of Morris water Maze was used to measure learning and memory ability and the results of LTP and LTD in hippocampus CA1 were recorded to observe the synaptic plasticity of hippocampus neurons. The results showed that compared with control group, the locomotion activity and learning ability for two models decreased extremely, while there was no apparent difference in the feedback of memory. Meanwhile, the synaptic plasticity of hippocampus neurons for two models decreased significantly and the level of serum cortisol increased evidently. These results suggested that both methods employed to build the models could cause rats depression and learning inhibition, but do no effects on the feedback of memory.
Subject(s)
Depression/physiopathology , Learning/physiology , Memory/physiology , Animals , Depression/blood , Depression/metabolism , Disease Models, Animal , Hippocampus/cytology , Hippocampus/metabolism , Hydrocortisone/blood , Male , Maze Learning , Neurons/metabolism , Rats , Rats, Sprague-DawleyABSTRACT
The expression of galanin and galanin receptor-2 in hippocampus and dorsal raphe nucleus of depression model was studied. The chronic stress rat model was adopted as the modal of depression. Open-field test was used to observe the transformation of their behavior and HPLC-EC was employed to analysis the level of blood serum cortisol. The method of in situ hybridization was used for testing the expression of Galanin and galanin receptor-2 in hippocampus and dorsal raphe nucleus and the method of RT-PCR was used to further analysis of the expression. The results showed that the locomotion activity decreased extremely after chronic stress, but the level of serum cortisol increased evidently. The expression of Galanin and its receptor-2 in hippocampus and dorsal raphe nucleus increased obviously. The higher expression for galanin and galanin receptor-2 in some brain area suggested that galanin probably takes part in the modulation of the function of neurons during the stress process.
