Levels of Amino Acid Neurotransmitters during Mouse Cerebellar Neurogenesis and in Histotypic Cerebellar Cultures

Abstract

The variation in the levels of excitatory (glutamate and aspartate) and inhibitory (GABA, glycine and taurine) neurotransmitters during neurogenesis in mouse cerebellum, from embryonic day (E) 15 until the young adult stage, was analyzed by high-pressure liquid chromatography. Between E15 and E21, high contents of GABA, glutamate and aspartate were detected, with the GABA levels approximately 2- to 3-fold higher than those of glutamate and aspartate. After birth, the levels of GABA remained high during the first 2 postnatal weeks and then reached a plateau comparable to adult values by the third week. The levels of glutamate and aspartate increased gradually from birth to the young adult stage, showing peak values at postnatal days (P) 3 and P11. Glycine and taurine were present at relatively low concentrations during the prenatal period, then rose significantly by about 4-fold after birth; their levels decreased by the end of the first postnatal week but increased gradually thereafter until reaching adult values by the third week. To determine the endogenous neurotransmitter production in the cerebellar cortex, primary histotypic cerebellar cultures prepared at P10 were analyzed and the in vitro transmitter contents were compared with the adult in situ values. The cultures showed about the same levels of glutamate and aspartate; however, their concentrations were lower by half than in vivo, suggesting that both play an equally important role in the excitatory neurotransmission of the cerebellar cortex internal circuitry pathways and that in mature cerebellum, about 50% of the excitatory synaptic inputs derive from the afferent climbing and mossy fibers. The in vitro GABA and glycine contents were comparable with the in vivo levels, whereas the taurine concentrations were about 5-fold lower in vitro than in vivo. These findings indicate that most of the GABA and glycine transmitters are produced intrinsically while a high proportion of taurine in the cerebellum comes from extracerebellar afferents. This study provides data on the changing levels of the amino acid neurotransmitters in developing mouse cerebellum and the relative proportions of neurotransmitter contents that are produced by intrinsic neurons in contrast to those derived from extrinsic afferent fibers.

Single-neuron identification of chemical constituents, physiological changes, and metabolism using mass spectrometry

“…In addition to the coexistence of Glu and GABA, consistent with previous studies reporting age-dependent changes in multiple neurotransmitter systems in brain tissue (36,37), we also found that the concentrations of amino acids neurotransmitters, including Glu and GABA, in single cells decrease with age. Interestingly, we observed that the correlation among single-cellular Gln, Glu, and GABA is much more significant in infants than that in children or adolescents.…”

“…( Changes in the Levels of Cytoplasmic Chemical Constituents at Different Stages of Brain Development. Previous reports suggest that the levels of amino acid neurotransmitters tend to decrease with age (36,37). Using single-cell MS, we investigated this idea at the single-neuron level.…”

Quantitative Assessment of Metabolic Changes in the Developing Brain of C57BL/6 Mice by In Vivo Proton Magnetic Resonance Spectroscopy

“…Comparing our data with those from Weiss et al, who also used high temporal resolution, our data correlated better with concentrations measured ex vivo by high-performance liquid chromatography during brain maturation in the thalamus and with concentrations in humans, (own unpublished data) [11,21,25,26]. For instance, in our study, the concentrations of tCr, tNAA, and Glx show a steady increase in the developing brain and reach a plateau when the brain maturation is finished.…”

Proton MRS of early post‐natal mouse brain modifications in vivo

“…Similarly to our in vivo MRS study, HPLC analysis indicated that the taurine content in the thalamus was twofold lower at D9 and D11 compared with those at D7 and P15 and at D19, twofold higher compared with the cerebellum and olfactory bulb. Comparison of ex vivo HPLC levels with those observed in vitro, in histotypic cerebellar cultures, demonstrated a content which was fivefold lower in vitro than ex vivo (13), suggesting that the high proportion of endogenous taurine observed in cerebellum could come from an extrinsic origin. In the rat brain, specific antibodies of high-affinity Tau transporters showed a predominant localisation in the cerebellum, in the neuronal Purkinje cell and in Bergmann glial cells (15).…”

“…Furthermore, the Tau content in thalamus is twofold higher than in other structures. When the Tau concentration was measured ex vivo by high-performance liquid chromatography (HPLC) during brain maturation in these three regions (12)(13)(14), its values decreased between birth and the young adult stage. Similarly to our in vivo MRS study, HPLC analysis indicated that the taurine content in the thalamus was twofold lower at D9 and D11 compared with those at D7 and P15 and at D19, twofold higher compared with the cerebellum and olfactory bulb.…”