Zinc functions in the central nervous system

脑屏障系统，即，血脑屏障和血脑脊髓液屏障对于脑中锌的体内平衡是重要的。锌通过这两个屏障供应给大脑。大部分锌作为锌金属蛋白存在于神经元和神经胶质细胞中。大脑中约10%的锌（可能是离子锌）存在于突触囊泡中，可能是突触神经传递中的内源性神经调质。含锌神经元是突触能神经元的一个亚类，它将锌隔离在突触前囊泡中，并以钙和脉冲依赖的方式释放锌，这一点已在大脑中得到证实，特别是在边缘系统如海马和杏仁核中。饮食锌剥夺影响锌稳态在大脑中。泡状富锌区域，即，海马体对饮食锌剥夺有反应，导致学习障碍和嗅觉功能障碍。通过喂饲锌充足的饲料，使学习障碍得到恢复。杏仁核神经元末梢释放的锌的螯合作用也可逆地干扰嗅觉识别。此外，锌稳态在大脑中的影响，由癫痫发作（癫痫）小鼠。癫痫发作的易感性，这可能会减少囊泡锌，也增强了缺锌。因此，锌在脑内的稳态与脑功能密切相关。囊泡锌可能通过谷氨酸参与兴奋性神经传递的调节。即使在成年动物和成年人中，充足的锌供应对大脑功能和预防神经系统疾病也很重要。

The brain barrier system, i.e., the blood-brain and blood-cerebrospinal fluid barriers, is important for zinc homeostasis in the brain. Zinc was supplied to the brain via both the barriers. A large portion of zinc serves as zinc metalloproteins in neurons and glial cells. Approximately 10% of the total zinc in the brain, probably ionic zinc, exists in the synaptic vesicles, and may serve as an endogenous neuromodulator in synaptic neurotransmission. The presence of zinc-containing neurons, a subclass of glutamatergic neurons, that sequester zinc in the presynaptic vesicles and release it in a calcium-and impulse-dependent manner has been demonstrated in the brain, especially in the limbic system such as hippocampus and amygdala. Dietary zinc deprivation affected zinc homeostasis in the brain. Vesicular zinc-enriched regions, i.e., the hippocampus, was responsive to dietary zinc deprivation, which caused learning impairment and olfactory dysfunction. The learning impairment was recovered by feeding with zinc-adequate diet. Olfactory recognition was also reversibly disturbed by the chelation of zinc released from amygdalar neuron terminals. Moreover, zinc homeostasis in the brain was affected by seizure in El (epilepsy) mice. The susceptibility to epileptic seizure, which may decrease vesicular zinc, was also enhanced by zinc deficiency. Therefore, zinc homeostasis in the brain is closely related to brain functions. Vesicular zinc may be involved in regulation of excitatory neurotransmission via glutamate. Even in adult animals and probably adult humans, adequate zinc supply is important for brain functions and prevention of neurological diseases.