Axon-Sparing Brain Lesioning Technique: The Use of Monosodium-L-Glutamate and Other Amino Acids

Simson, Earl L.; Gold, Richard M.; Standish, Leanna J.; Pellett, Peter L.

doi:10.1126/science.910144

Cited by 78 publications

(25 citation statements)

References 22 publications

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“…These mutant strains are not widely available, but the GHdeficient mouse can be produced in normal animals as well. MSG produces G H deficiency of hypothalamic origin in mice (22)(23)(24), which is due to selective destruction of G R F neurons in the arcuate nucleus as demonstrated in rats bji immunohistochemistry (48). Another hypothalamic GH-deficient model may be produced by GTG, a toxic form of glucose.…”

Section: Immunoliistochemical Identification Of Mcrf Neuronsmentioning

confidence: 99%

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Characterization and Localization of Mouse Hypothalamic Growth Hormone‐Releasing Factor and Effect of Gold Thioglucose‐Induced Hypothalamic Lesions

Miki¹,

Ono²,

Asakawa-Yasumoto³

et al. 1994

J Neuroendocrinology

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Hypothalamic growth hormone-releasing factor (GRF) in higher mammals, including human GRF, is a 44 amino acid residue peptide and is highly homologous in structure. By contrast, mouse GRF (mGRF) recently deduced by cDNA cloning consists of only 42 residues and shows relatively low homology to the GRFs of higher mammals and the same rodent species, rat. To characterize and localize the predicted mature mGRF peptide in the hypothalamus, we have generated its antiserum and developed a homologous radioimmunoassay. lmmunoreactive mGRF in the acid hypothalamic extract was eluted as a single peak at a position identical to that of synthetic peptide on both gel filtration chromatography and reverse-phase high-performance liquid chromatography (HPLC). Secretion of immunoreactive mGRF from incubated hypothalami increased several fold in response to 50 mM K' , and this rise was abolished in the absence of medium Ca'+. Only a single peak of irnmunoreactive mGRF that coeluted with synthetic replicate was observed after the K+-stimulated medium was extracted on Bond Elut C18 cartridges and applied on reverse-phase HPLC. lmmunohistochemistry identified many mGRF-positive cell bodies in the arcuate nucleus and dense bundles of immunoreactive fibers in the median eminence. Treatment of mice with gold thioglucose (GTG), a chemical agent known to cause hypothalamic lesions, markedly depleted both content and in vitro secretion of immunoreactive mGRF. The decline in mGRF secretion was greater in GTG obese than in nonobese mice, whereas somatostatin secretion was not affected by GTG treatment. AS compared to the previous findings obtained on rat GRF, mouse had approximately the same content of hypothalamic GRF, but retained only one third the capacity to release GRF in response to the same depolarizing stimulus.These findings demonstrate that mouse hypothalamus contains and secretes a mGRF-like molecule which has immunological and chromatographic characteristics identical to that predicted by molecular cloning. The depolarization-evoked, Ca' ' -dependent release of immunoreactive mGRF and its neuronal localization in the arcuate nucleus-median eminence region indicate that it functions as a hypophysiotropic hormone of physiological importance. GTG produces hypothalamic GRF deficiency, probably sparing hypophysiotropic somatostatin neurons, and could be used to generate a mouse model for human GRF-deficient dwarfism.

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Section: Immunoliistochemical Identification Of Mcrf Neuronsmentioning

confidence: 99%

“…In normal mice, growth failure is induced by chemical destruction of the hypothalamus. The most popular agent used is monosodium glutamate (MSG) (22)(23)(24). Also, GTG may bc employed for this purpose since this agent is reported to cause necrotic hypothalamic lesions in mice (25)(26)(27).…”

mentioning

confidence: 99%

Characterization and Localization of Mouse Hypothalamic Growth Hormone‐Releasing Factor and Effect of Gold Thioglucose‐Induced Hypothalamic Lesions

Miki¹,

Ono²,

Asakawa-Yasumoto³

et al. 1994

J Neuroendocrinology

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“…MSG administered sc during the neonatal period has been reported to destroy a vast majority of the perikarya in the hypothalamic arcuate nuclei while sparing the axons that passed through (Simson et al, 1977). We have shown that immunoreactive GRF content in SME was severely depleted by neonatal MSG treatment.…”

Section: Discussionmentioning

confidence: 54%

Production of antisera to growth hormone-releasing factor: Usefulness in radioimmunoassay and passive immunization.

et al. 1985

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We have produced two antisera (R-1 & R-2) to human growth hormonereleasing factor (GRF) NH2. Both antisera can be used for human GRF radioimmunoassay (RIA) at a final dilution of 1: 50000. The antiserum R-2 was specific for the C-terminal amidated sequence of human GRF-44 and selectively recognized GRF [1-44] NH2 but not GRF [1-44] OH or GRF OH. The antiserum R-1 also significantly bound 125I-rat GRF OH at a final dilution of 1: 5000 and enabled us to establish RIA for rat GRF. In both RIA systems, intra-and inter-assay coefficients of variation at 50% inhibition were 8 and 12%, respectively. A median effective dose was 90-120 pg in human GRF RIA and 250-300 pg in rat GRF RIA. Utilizing the RIA, we demonstrated that the hypothalamic GRF content in rats which received monosodium glutamate during the neonatal period was less than 20% of that of controls.However, the hypothalamic GRF content was not altered in rats made hypothyroid by methimazole administration, another condition known to greatly impair GH secretion. An iv administration of the antiserum R-1 significantly suppressed GH release following the injection of antisomatostatin serum. Thus, these antisera can be a useful tool in examining the physiological and/or pathophysiological roles of GRF in human and rat.

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“…In contrast, small amounts of L-glut are neurotoxic when administered directly into the brain parenchyma (38). Intracerebroventricular infusion of NMDA (7) or administration of L-glut to the pial surface (28) in rats results in BBB dysfunction and brain edema that could be attenuated with MK801, an NMDA receptor antagonist.…”

Section: Discussionmentioning

confidence: 99%

Cerebromicrovascular endothelial cells are resistant to l-glutamate

Domoki

Kis

Gáspár

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Cerebral microvascular endothelial cells (CMVECs) have recently been implicated as targets of excitotoxic injury by L-glutamate (L-glut) or N-methyl-Daspartate (NMDA) in vitro. However, high levels of L-glut do not compromise the function of the blood-brain barrier in vivo. We sought to determine whether primary cultures of rat and piglet CMVECs or cerebral microvascular pericytes (CMVPCs) are indeed sensitive to L-glut or NMDA. Viability was unaffected by 8-h exposure to 1-10 mM L-glut or NMDA in CMVECs or CMVPCs isolated from both species. Furthermore, neither 1 mM L-glut nor NMDA augmented cell death induced by 12-h oxygen-glucose deprivation in rat CMVECs or by 8-h medium withdrawal in CMVPCs. Additionally, transendothelial electrical resistance of rat CMVEC-astrocyte cocultures or piglet CMVEC cultures were not compromised by up to 24-h exposure to 1 mM L-glut or NMDA. The Ca 2ϩ ionophore calcimycin (5 M), but not L-glut (1 mM), increased intracellular Ca 2ϩ levels in rat CMVECs and CMVPCs assessed with fluo-4 AM fluorescence and confocal microscopy. CMVEC-dependent pial arteriolar vasodilation to hypercapnia and bradykinin was unaffected by intracarotid infusion of L-glut in anesthetized piglets by closed cranial window/intravital microscopy. We conclude that cerebral microvascular cells are insensitive and resistant to glutamatergic stimuli in accordance with their in vivo role as regulators of potentially neurotoxic amino acids across the blood-brain barrier.N-methyl-D-aspartate; blood-brain barrier; cerebrovascular reactivity; glutamate excitotoxicity; intracellular calcium L-GLUTAMATE (L-glut) is one of the most important excitatory amino acids in the central nervous system. Apart from its well-known neurotransmitter role, L-glut plays a critical role in ammonia removal from the brain. L-Glut transported from the blood plasma takes up ammonia and leaves as L-glutamine (12). This balanced L-glutamate/L-glutamine countertransport is regulated by cerebral microvascular endothelial cells (CMVECs) forming the blood-brain barrier (BBB). Furthermore, CMVECs can pump L-glut from the brain to the blood, and thus they provide a functional interface for the regulated bidirectional transport of L-glut (18, 39). Human blood plasma L-glut levels range between 20 and 200 M, and they may exceed 700 M after ingestion of high amounts of L-glut under experimental conditions (4, 41). These plasma L-glut concentrations are not neurotoxic in vivo, although these levels are excitotoxic to neurons in vitro, suggesting that CMVECs are resistant to high L-glut levels and prevent the passive transport of L-glut into the brain.Surprisingly, several recent reports have proposed that the L-glut levels that occur during cerebral ischemia can injure or kill CMVECs via excitotoxic mechanisms in vitro. CMVECs have been reported to possess various L-glut receptor subunits or L-glut binding sites in rat, piglet, or human CMVECs (1,5,27,34,36,45). High concentrations of L-glut (1-3 mM), at least in vitro, are claimed to result in N-met...

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Axon-Sparing Brain Lesioning Technique: The Use of Monosodium-L-Glutamate and Other Amino Acids

Cited by 78 publications

References 22 publications

Characterization and Localization of Mouse Hypothalamic Growth Hormone‐Releasing Factor and Effect of Gold Thioglucose‐Induced Hypothalamic Lesions

Characterization and Localization of Mouse Hypothalamic Growth Hormone‐Releasing Factor and Effect of Gold Thioglucose‐Induced Hypothalamic Lesions

Production of antisera to growth hormone-releasing factor: Usefulness in radioimmunoassay and passive immunization.

Cerebromicrovascular endothelial cells are resistant to l-glutamate

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