A Developmental Study of Glycerol Oxidation by Rat Brain

Mc, McKenna; Mm, Fife; Jt, Tildon

doi:10.1159/000112241

Cited by 4 publications

(11 citation statements)

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“…The data show that the rate of oxidation of glycerol in vitro is different in discrete brain areas and that the oxidation of glycerol in each area changes during brain development. A preliminary report of these data has been presented (McKenna et al, 1985).…”

Section: Discussionmentioning

confidence: 99%

“…Glycerol oxidation in brain is unique in that the rate of oxidation is biphasic (Tildon and Roeder, 1980;McKenna et al, 1986). We have previously shown that brain tissue has the capability to oxidize large concentrations of glycerol, which could be potentially toxic to the central nervous system (McKenna et al, 1986).…”

Section: Discussionmentioning

confidence: 99%

“…We have previously shown that brain tissue has the capability to oxidize large concentrations of glycerol, which could be potentially toxic to the central nervous system (McKenna et al, 1986). The rate of oxidation of glucose and 3-hydroxybutyrate levelled off at a concentration of 2.5 mM and 1.0 mM, respectively; the rate of glycerol oxidation, however, continued to increase, even at a substrate concentration of 10.0 mM (Tildon et al, 1983;McKenna et al, 1986). Evidence of central nervous system glycerol toxicity (i.e., lethargy, vomiting, loss of consciousness, and sometimes retardation) has been reported in a number of young patients with unidentified metabolic disorders (MacLaren et al, 1975), with fructose-1, 6-diphosphatase deficiency (Greene et al, 1972), with multiple liver enzyme deficiencies (Wapnir et al, 1982), and with the infantile and iuvenile forms of dvcerol kinase…”

Section: Discussionmentioning

confidence: 99%

“…We recently characterized the oxidation of glycerol by developing rat brain and demonstrated that the oxidation of glycerol was significantly lower in whole brain from neonatal and 1-to 3-day old rats than in older animals (McKenna et al, 1986). In whole brain the rate of glycerol oxidation increased during the second to third week of life to levels comparable to those found in adults.…”

mentioning

confidence: 92%

“…A high rate of glycerol oxidation may reflect the importance of glycerol as an energy substrate in that area of brain. In addition, an area of brain with a large capability to oxidize glycerol may be relatively protected from the toxic effects of excess glycerol (Greene et al, 1972;Wapnir et al, 1982;MacLaren et al, 1975;McCabe et al, 1977;McCabe, 1983;Ginns et al, 1984;McKenna et al, 1986). The rate of oxidation of a particular substrate may be very different in individual brain areas than in whole brain.…”

mentioning

confidence: 99%

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Glycerol oxidation in discrete areas of rat brain from young, adolescent, and adult rats

Tildón

Bezold

1988

J of Neuroscience Research

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We have reported previously that the oxidation rate of [1,3-14C] glycerol to 14CO2 is lower in whole brain homogenates from neonatal rats and increases about 30% during the suckling period to adult levels. To determine whether there are developmental changes in glycerol oxidation in discrete regions of brain, we examined the oxidation of glycerol by homogenates of hypothalamus, cerebellum, brain stem, hippocampus, and cerebral cortex of young (4-6 days) and older (18-20 days) pups and adult (greater than 90 day) rats. The oxidation was measured at both low (0.2 mM) and high (2.0 mM) concentrations of glycerol, since the oxidation of glycerol by brain tissue has been shown to exhibit biphasic kinetics. At each age, and with both concentrations of glycerol, there were significant differences among the discrete brain regions. Although the rate of glycerol oxidation increased with age in most areas of brain, each brain region had a distinct developmental profile. In the hypothalamus, the oxidation of glycerol increased significantly between 4-6 days and adult levels at 18-20 days. The oxidation of glycerol was essentially the same in homogenates of cortex from young and older pups, but it was significantly increased in adults. In contrast with other brain regions, the oxidation of glycerol by brain stem was highest at 4-6 days and significantly decreased with age. The developmental profile of glycerol oxidation in hippocampus and cerebellum was particularly complex, since it increased with age at low, but not at high, concentrations of glycerol. This developmental pattern in hippocampus and cerebellum could be related to changes in the biphasic kinetics of glycerol oxidation and suggests that glycerol metabolism is different in these two areas of brain compared with other areas of brain.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 92%

mentioning

confidence: 99%

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Glycerol oxidation in discrete areas of rat brain from young, adolescent, and adult rats

Tildón

Bezold

1988

J of Neuroscience Research

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Metabolic Alterations in Brain Autopsies: Proton NMR Identification of Free Glycerol

1996

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Competition of glycerol with other oxidizable substrates in rat brain

McKenna¹,

Bezold²,

Kimatian³

et al. 1986

Biochemical Journal

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The rate of conversion of [1,3-14C]glycerol into 14CO2 was measured in the presence and absence of unlabelled alternative substrates in whole homogenates from the brains of young (4-6 and 18-20 days old) and adult rats. Unlabelled glucose decreased 14CO2 production from [1,3-14C]glycerol by about 40% at all ages studied. Unlabelled 3-hydroxybutyrate significantly decreased the 14CO2 production from both low (0.2 mM) and high (2.0 mM) concentrations of glycerol in 4-6- and 18-20-day-old rat pups. However, the addition of 3-hydroxybutyrate had no effect on the rate of 14CO2 production from 2.0 mM-glycerol in adult rats, suggesting that the interaction of 3-hydroxybutyrate with glycerol in adult rat brain is complex and may be related to the biphasic kinetics previously reported for glycerol oxidation. Unlabelled glutamine decreased the production of 14CO2 by brain homogenates from 18-20-day-old and adult rats, but not in 4-6-day-old rat pups. In the converse situation, the addition of unlabelled glycerol to whole brain homogenates had little effect on the rate of 14CO2 production from [6-14C]glucose, 3-hydroxy[3-14C]butyrate and [U-14C]glutamine, although some significant differences were noted. Collectively these results suggest that glycerol and these other substrates may be metabolized in separate subcellular compartments in brain such that the products of glucose, 3-hydroxybutyrate and glutamine metabolism can dilute the oxidation of glycerol, but the converse cannot occur. The data also demonstrate that there are complex age-related changes in the interaction of glycerol with 3-hydroxybutyrate and glutamine. The fact that glycerol oxidation was only partially suppressed by the addition of 1-5 mM-glucose, -3-hydroxybutyrate or -glutamine could also suggest that glycerol may be selectively utilized as an energy substrate in some discrete brain region.

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A Developmental Study of Glycerol Oxidation by Rat Brain

Cited by 4 publications

References 24 publications

Glycerol oxidation in discrete areas of rat brain from young, adolescent, and adult rats

Glycerol oxidation in discrete areas of rat brain from young, adolescent, and adult rats

Metabolic Alterations in Brain Autopsies: Proton NMR Identification of Free Glycerol

Competition of glycerol with other oxidizable substrates in rat brain

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