Absence of change in hepatic lactate metabolism after burn injury

A Metabonomics Approach to Drug Toxicology in Liver Disease and its Application in Traditional Chinese Medicine

BACKGROUND

The progression of liver disease causes metabolic transformation in vivo and thus affects corresponding endogenous small molecular compounds. Metabonomics is a powerful technology which is able to assess global low-molecular-weight endogenous metabolites in a biological system. This review is intended to provide an overview of a metabonomics approach to the drug toxicology of diseases of the liver.

METHODS

The regulation of, and relationship between, endogenous metabolites and diseases of the liver is discussed in detail. Furthermore, the metabolic pathways involved in drug interventions of liver diseases are reviewed. Evaluation of the protective mechanisms of traditional Chinese medicine in liver diseases using metabonomics is also reviewed. Examples of applications of metabolite profiling concerning biomarker discovery are highlighted. In addition, new developments and future prospects are described.

RESULTS

Metabonomics can measure changes in metabolism relating to different stages of liver disease, so metabolic differences can provide a basis for the diagnosis, treatment and prognosis of various diseases.

CONCLUSION

Metabonomics has great advantages in all aspects of the therapy of liver diseases, with good prospects for clinical application.

Metabolic effects of l-alanyl-glutamine in burned rats

Burn injury elicits a sustained hypermetabolic state characterized by accelerated hepatic synthesis of amino acids and proteolysis leading to negative nitrogen balance. This paper was aimed at studying the effects l-alanyl-glutamine (Ala-Gln) exogenous offer to rats submitted to thermal burn. Twenty-four anesthetized male Wistar rats were submitted to scald burn of dorsal skin (30% body surface). Eighteen and 42-h later rats were randomized to receive (by gavage) 2ml of water (G-1) or equal volume (0.5g/kg weight/day) of Ala-Gln solution (G-2). Tissue and blood samples were collected at the end of 24 and 48-h post-burn trauma (PBT). Blood concentrations of metabolites (glucose, pyruvate, lactate and ketone bodies) were similar in all groups. There were significant differences in tissue metabolites concentrations in Ala-Gln treated rats (G-2) compared to control (G-1) following scald injury. The administration of Ala-Gln to burned rats induces a fall ATP (muscle, healthy skin), pyruvate and ketone bodies (liver) concentrations 24-h PBT. It also induces significant increase of lactate (burned skin) 24-h and glucose (liver) 28/48-h PBT. Rise of tissue lactate concentrations may be due to enhanced anaerobic glycolysis resulting from increased availability of glutamate, derived from glutamine, with possible activation of the malate-aspartate shuttle.

Efeitos metabólicos da glutamina em ratos submetidos à queimadura por água fervente (escaldadura)

OBJETIVO: Investigar os efeitos metabólicos da L-glutamina (Gln) em ratos anestesiados submetidos à queimadura por água fervente. MÉTODOS: Foram estudados vinte e quatro ratos Wistar machos, anestesiados, submetidos a queimaduras da pele dorsal após exposição à água quente (100ºC) durante 10 segundos (30% de superfície corporal). Os ratos foram randomizados para receber, por gavagem, 2ml de água (G-1) ou igual volume de solução de Gln (0,5g/peso/dia) (G-2). Amostras de tecido (pele sadia e queimada, músculo e fígado) e sangue foram coletadas 24h (D1) e 48h (D2) pós-trauma para análise enzimática. RESULTADOS: A oferta de Gln induziu aumento significante nas concentrações de glicose na pele saudável em animais do G-2 no D2, e na pele queimada em G-2/D1. As concentrações de lactato também aumentaram significantemente em G-2/D1 no músculo (11,29 ± 1,25 mmol/g contra 7,43 ± 0,93 mmol/g - p<0,05) e no G-2/D2 no fígado (7,68 ± 1,49 mmol/g contra 3,27 ±0,67 mmol/g p<0,01), e em pele sadia (5,30 ± 0,42 mmol/g contra 3,57 ± 0,38 mmol/g - p<0,05). As concentrações de piruvato diminuíram significantemente no grupo G-2/D1 (músculo e fígado) e aumentaram na pele sadia no grupo G-2/D2. As concentrações de ATP diminuíram significantemente no músculo em G-2 nos tempos D1 e D2. CONCLUSÕES: A oferta de Gln sinaliza para utilização de piruvato para glicólise preponderantemente anaeróbica no músculo. O aumento nas concentrações de lactato tecidual pode vir a ser decorrente da oferta exógena de Gln, que transformada em glutamato, leva à ativação do ciclo malato-aspartato com conseqüente favorecimento da glicólise anaeróbica. A oferta de Gln induz a possível aumento na captação de glicose tanto por pele sadia quando na pele queimada. Houve falha de desenvolvimento da hipercetonemia adaptativa ao jejum em ambos os grupos. A oferta exógena de Gln parece não induzir alteração na ureagênese.