Nerve Astrocytes

Genetic evidence supports the importance of coordinated expression and distributions of a2 or a3 Na+/K+ pump isoforms with the Na+/Ca2+ exchanger (NCX) and Ca2+ pumps to function in excitable and contractile cells deletion of one copy of the a2 Na+/K+ pump gene in mice leads to increased contractile force in cardiac and skeletal muscle while deletion of one copy of the al gene leads to reduction of contractile force [25]. In rat optic nerve astrocytes, deletion of the a2 gene or ouabain treatment of cells expressing a2 leads to increased capacitative calcium entrance responses, which reflect a decreased ability to rapidly remove cytosolic Ca2+ [26]. 

Hartford, A. K., Messer, M. L., Moseley, A. E., Lingrell, J. B. and Delamere, N. A. Na,K-ATPase alpha-2 inhibition alters calcium responses in optic nerve astrocytes. Glia 45 229-237, 2004. 

Skoff, R.P. (1990) Gliogenesis in rat optic nerve astrocytes are generated in a single wave before oligodendrocytes. Dev. Biol. 139 149-168. 

Saez ET, Pehar M, Vargas MR, Barbeito L, Maccioni RB (2006) Production of nerve growth factor by beta-amyloid-stimulated astrocytes induces p75NTR-dependent tau hyperphosphorylation in cultured hippocampal neurons. J Neurosci Res 84 1098-1106 Sala C, Roussignol G, Meldolesi J, Fagni L (2005) Key role of the postsynaptic density scaffold proteins Shank and Homer in the functional architecture of Ca homeostasis at dendritic spines in hippocampal neurons. J Neurosci 25 4587 592 Santello M, Volterra A (2008) Synaptic modulation by astrocytes via Ca(2-l-)-dependent glutamate release. Neuroscience 158 253-9... 

Miller RH, David S, Patel R, Abney ER, Raff MC 1985 A quantitative immunohistochemical study of macroglial cell development in the rat optic nerve in vivo evidence for two distinct astrocyte lineages. Dev Biol 111 35-41... 

Histamine is stored within and released from neurons but a neuronal transporter for histamine has not been found. Newly synthesized neuronal histamine is transported into TM neuronal vesicles by the vesicular monoamine transporter VMAT2 [16]. Both in vivo and in vitro studies show that depolarization of nerve terminals activates the exocytotic release of histamine by a voltage- and calcium-dependent mechanism. Once released, histamine activates both postsynaptic and presynaptic receptors. Unlike the nerve terminals from other amine transmitters, however, histaminergic nerve terminals do not exhibit a high-affinity uptake system for histamine [5, 9, 23]. Astrocytes may contain a histamine transport system. 

The astrocyte-neuron lactate shuttle hypothesis is controversial. In recent years the possibility that lactate, formed within the brain and released by astrocytes, is an important neuronal substrate both for energy and incorporation into neurotransmitters has been the subject of many studies and considerable controversy. There is evidence that suggests transient release of lactate in human brain on stimulation [48,8,88], Little is known about the highly active metabolism that takes place in the many elaborate, lamellar distal processes of astrocytes dispersed through the neuropil and interacting with an estimated >100,000 synapses [82, and references therein]. However, it is well established that astrocytes do respond to neuronal activity [89], For example, in the isolated mouse optic nerve preparation, upon stimulation, astrocytic glycogen... 

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