Effects of varying doses of methionine sulfoximine on liver glutamine synthetase activity and time courses of blood and urinary nitrogenous compounds in the chicken (Gallus domesticus)

Glutamine depletion potentiates leucocyte-dependent inflammatory events induced by carrageenan or Clostridium difficile toxin A in rats

This research investigated the effect of glutamine (Gln) depletion on leucocyte-dependent inflammatory events. Rats were treated intraperitoneally, 16 hr prior to the peak of every parameter evaluated, with either 0.9% NaCl, methionine-sulphoximine (MSO, an inhibitor of endogenous Gln synthesis, 25 mg/kg) or with MSO + Gln (MSO as above plus Gln 3 g/kg in three doses). MSO-induced Gln depletion increased paw oedema induced both by carrageenan (Cg) and by Clostridium difficile toxin A (TxA) (66.2% and 45.5%, respectively; P < 0.05). In dextran-injected animals, oedema and myeloperoxidase (MPO) activity were not modified by Gln depletion. In Cg-treated paws, Gln depletion increased MPO activity by 44% (P < 0.05), interleukin-1beta (IL-1beta) and tumour necrosis factor-alpha (TNF-alpha) concentrations by 47% and 52%, respectively (P < 0.05), and immunostaining for TNF-alpha in paw tissue. In TxA-injected paws, Gln depletion increased MPO activity (46%; P < 0.05). Gln depletion increased Cg- and TxA-induced neutrophil migration to subcutaneous air pouches by 56% and 77% (P < 0.05), respectively, but did not affect migration induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP). Gln infusions reversed all the effects of MSO. Leucocyte counts did not differ between groups. Gln depletion potentiates acute inflammation, possibly by increasing neutrophil migration through resident cell activation and production of IL-1beta and TNF-alpha. Gln supplementation reverses these effects and may be useful during inflammatory catabolic stress.

Incorporation of intraportally infused [15N]ammonia into urinary uric acid in cockerels pretreated with methionine sulfoximine

1. Measurements were made in situ to determine the incorporation of intraportally infused ammonia-15N into urinary uric acid in cockerels pre-treated with methionine sulfoximine (MSM), a glutamine synthetase inhibitor. 2. The incorporation of 15N into urinary uric acid was 34% of the infused amount in MSM-treated birds. This was not significantly different from the value of 46% for control birds. 3. Pre-treatment with MSM inhibited the activity of liver glutamine synthetase to 7% of the control value and decreased the incorporation of the infused ammonia-15N into plasma glutamine amide-N to 3% of the control. 4. Increases in glutamine concentrations in the blood, liver and kidney caused by the infusion of ammonia were also completely inhibited by the MSM treatment (P less than 0.05). 5. It is concluded that in the cockerel ammonia-N can be incorporated into uric acid other than by glutamine formation.