ABSTRACT
Plasticity in the glutamatergic synapses on striatal medium spiny neurons (MSNs) is not only essential for behavioral adaptation but also extremely vulnerable to drugs of abuse. Modulation on these synapses by even a single exposure to an addictive drug may interfere with the plasticity required by behavioral learning and thus produce impairment. In the present work, we found that the negative reinforcement learning, escaping mild foot-shocks by correct nose-poking, was impaired by a single in vivo exposure to 20 mg/kg cocaine 24 h before the learning in mice. Either a single exposure to cocaine or reinforcement learning potentiates the glutamatergic synapses on MSNs expressing the striatal dopamine 1 (D1) receptor (D1-MSNs). However, 24 h after the cocaine exposure, the potentiation required for reinforcement learning was disrupted. Specific manipulation of the activity of striatal D1-MSNs in D1-cre mice demonstrated that activation of these MSNs impaired reinforcement learning in normal D1-cre mice, but inhibition of these neurons reversed the reinforcement learning impairment induced by cocaine. The results suggest that cocaine potentiates the activity of direct pathway neurons in the dorsomedial striatum and this potentiation might disrupt the potentiation produced during and required for reinforcement learning.
ABSTRACT
Objective To prepare recombinant human epidermal growth factor (rhEGF) sustained-release microspheres and evaluate their morphology, rhEGF releasing activities and cell proliferation activity in vitro and compare difference of rhEGF sustained-release microspheres and rhEGF in facilitaring ulcer healing in diabetic rats. Methods (1) rhEGF sustained-release microspheres were prepared by the modified double emulsion method. Morphology of the microspheres was detected by transmission electron microscope and size distribution measured by laser granularity meter/Zeta electric potential meter. ELISA assays were applied to determine rhEGF releasing. (2)Proliferation of mouse fibroblasts was analyzed by MTr method. (3) Diabetic rat models were prepared and divided into four groups, ie, rhEGF sustained-release mierospheres group (Group A), rhEGF stock solution group (Group B), blank sustainedrelease mierospheres group (Group C) and PBS meustruum control group (Group D), which were given drug once a day. The wound healing rate was calculated by taking photographs at days 3,7,14 and 21. Skin specimens from the wound edge were harvested partially for observation of hydroxyproline (HYP) contents. Immunohistochemistry was employed to detect integrin 131 and keratin-19 and measure their positive staining area ratio. Results (1) The particle diameter of rhEGF sustained-release microspheres was 193.5 nm, with relative uniform particle diameter distribution. There showed no conglutination among rhEGF susrained-release microspheres, with good dispersibility. Releasing drug lasted for 24 hours and accorded with Higuchi release kinetic model. (2) Different concentrations of rhEGF sustained-release microspheres could promote the proliferation of mouse fibroblast, especially the concentration of 10 μg/L (P <0.05, compared with the control). (3) From the 7th day after treatment, Group A had the fastest wound healing rate, with statistical difference compared with other three groups (P < 0.05). Group A had higher HYP contents and positive area ratio of integrin β1 and keratin-19 than Group B. Conclusions rhEGF sustained-release microspheres prepared by the modified double emulsion method have uniform particle size and can last release for 24 hours. Compared with rhEGF stock solution, rhEGF sustained-release microspheres have faster and better ulcer healing and higher healing quality in diabetic rats.
ABSTRACT
Objective To explore the effect of Ligustrazine on neurogenesis in cortex after focal cerebral ischemia in rats. Methods Focal cerebral ischemia was induced by left middle cerebral arteryocclusion with asuture. Two hours later, injection of Ligustrazine (80 mg/kg, 1 time/d) was performed peritoneally. Four hours after the ischemia,5-bromodeoxyuridine (BrdU) (50 mg/kg, 1 time/d) was injected peritoneally. At 7 d, 14 d and 21 d after ischemia,BrdU positive cells in the cortex were observed by immunohistochemical staining. Results In ischemic model group, at 7 day, sparsely-distributed BrdU positive cells were observed in the Ⅱ - Ⅵ layers of the ipsilateral cortex, with a band-like distribution in ischemic penumbra. With the prolongation of ischemia, the number of BrdU positive cells increased.In Ligustrazine group, BrdU positive cells were also observed in the Ⅱ - Ⅵ layers of the cortex, with an intense distribution in ischemic penumbra. The numbers of BrdU positive cells at 7 d, 14 d and 21 d were more than those in ischemic model group respectively. Conclusion Ligustrazine increases the proliferated cells in cortex after focal cerebral ischemia in rats. The results suggest that it may be useful for promoting self-repair after ischemia.
ABSTRACT
Objective To develop a method to analyze functional grouping cDNA microarray gene expression in microvessels and neurons from rat brain using laser capture microdissection(LCM). Methods Microvessels and neurons were captured using the PixCell ⅡLCM instrument. The total RNA was extracted from the LCM samples according to the manufacturer's protocol of RNAqueous-Micro kit. The total RNA were processed for one round of T7-based RNA amplification; cDNA probe were synthesized using gene-specific primer and labeled for cDNA microarray analysis. Results Amplified RNA from microvessels and neurons allowed us to measure 96 gene expression in functional grouping cDNA microarray. Conclusion LCM allowed us to harvest pure microvessels and neurons from their native tissue environment, combined with methods of T7 RNA amplification and gene-specific primer amplification so that we can analyze functional grouping cDNA profiling in LCM samples.