Neuron：大麻素受体拮抗剂影响大脑发育
生物谷报道：5月8日，美国麻省理工大学研究人员在Neuron杂志上报告说，大麻素受体拮抗剂类减肥药物可能会危害儿童大脑发育。
大麻素受体拮抗剂由于能通过阻断大脑组织中大麻素受体来降低人的食欲，因而被开发成一种新的减肥药物，如法国塞诺菲－安万特制药集团研发的新型减肥药利莫纳班。
通常说的大麻药物是从植物大麻中提取而来，大麻中含有的特殊活跃化合物统称为大麻素。人体内也会产生大麻素，被称为内源性大麻素。内源性大麻素可以帮助调节人体食物摄入、能量储存和消耗。
研究人员通过老鼠实验发现，大麻素受体拮抗剂在降低人的食欲的同时，可能也会抑制儿童神经系统发育时所必需的大脑适应性重塑。
大脑有根据环境调整神经功能的能力，这对于儿童和动物幼崽的大脑发育特别重要。例如，把新生老鼠一只眼睛蒙上，即便是一天，大脑中大部分的神经键也会转向另一只未被蒙上的眼睛，这就是幼鼠大脑的适应性重塑功能。然而，当实验幼鼠被注射大麻素受体拮抗剂后，研究人员发现神经键无法转向大脑的特定区域，大脑适应性重塑能力消失了。
生物谷推荐原始出处：
Neuron，Vol 58, 340-345, 08 May 2008，Cheng-Hang Liu, Mark F. Bear
Cannabinoid Receptor Blockade Reveals Parallel Plasticity Mechanisms in Different Layers of Mouse Visual Cortex
Cheng-Hang Liu,1 Arnold J. Heynen,1 Marshall G. Hussain Shuler,1 and Mark F. Bear1,
1 Howard Hughes Medical Institute, The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Corresponding author
Mark F. Bear
mbear@mit.edu
Summary
The ocular dominance (OD) shift that occurs in visual cortex after brief monocular deprivation (MD) is a classic model of experience-dependent cortical plasticity. It has been suggested that OD plasticity in layer 2/3 of visual cortex precedes and is necessary for plasticity in the thalamocortical input layer 4. Here, we show in mouse visual cortex that rapid OD plasticity occurs simultaneously in layers 2/3 and 4. Remarkably, pharmacological blockade of cannabinoid receptors completely prevents the OD shift in layer 2/3, leaving plasticity intact in layer 4. Thus, experience-dependent cortical modifications in layers 2/3 and 4 can occur in parallel, via distinct mechanisms. These findings simplify the mechanistic description of plasticity in layer 4, force a revision in the interpretation of previous studies in which laminar differences in OD plasticity mechanisms were unrecognized, and have important implications for the therapeutic use of cannabinoid receptor antagonists in humans.
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