Testicular Reaction to Prolonged Exposure to Nitrous Oxide

Kripke, Benjamin J.; Kelman, Asher D.; Shah, Nishant K.; Balogh, Károly; Handler, Alfred H.

doi:10.1097/00000542-197602000-00002

Cited by 44 publications

(13 citation statements)

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“…The testicular histologic changes in N2O-exposed rats are similar to those seen in dietary B12-deficient rats, as follows: B12-deficient rats had a reduced wet weight in their testes (10,11) and the dry weight of testes from the N2O-exposed rats was also lower after 32 d of N2O exposure (21). Both rats' testes show abnormal spermatogenesis, such as aplasia of sperm and spermatoids.…”

Section: Discussionmentioning

confidence: 52%

“…The casein diet contains more methionine than soybean protein does, because a primary limiting amino acid of soybean protein, generally known as legume protein, is methionine. Interestingly, the N 2 O-exposed rats' testes showed loss of dry weight and reduced spermatogenesis ( 21 ). Together, these lines of evidences imply that methionine synthase plays an important role in maintaining testicular function.…”

Section: Testicular Injury To Rats Fed On Soybean Protein-based Vitammentioning

confidence: 81%

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Testicular Injury to Rats Fed on Soybean Protein-Based Vitamin B12-Deficient Diet Can Be Reduced by Methionine Supplementation

Yamada

Kawata

Wada

et al. 2007

J Nutr Sci Vitaminol

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SummaryWe have previously reported that rats fed on a vitamin B 12 (B 12 )-deficient diet containing 180 g soybean protein per kg diet showed marked histologic damage in their testes. In this paper, we report the effect of B 12 -deficiency on B 12 -dependent methionine synthase in the rats' testes and the effect of methionine supplementation of the diet on testicular damage. Rats were fed the soybean protein-based B 12 -deficient diet for 120 d. We confirmed that those rats were in serious B 12 -deficiency by measuring urinary methylmalonic acid excretion and B 12 content in tissues. Methionine synthase activity in the testis of the B 12 -deficient rats was less than 2% of that in B 12 -supplemented (control) rats. To complement disrupted methionine biosynthesis, methionine was supplied in the diet. A supplement of 5 g D,L-methionine per kg diet to the B 12 -deficient diet did not affect urinary methylmalonic acid excretion of B 12 -deficient rats. The testicular histology of rats fed the methioninesupplemented B 12 -deficient diet was almost indistinguishable from that of control rats. Thus, we conclude that the lowered testicular methionine synthase activity is the primary cause of the histologic damage due to B 12 -deficiency and that methionine supplementation to the diet can reduce the damage. These findings would indicate the importance of the methionine synthase activity, especially for testicular function. Key Words vitamin B 12 -deficiency, rat, testis, methionine synthase In mammals, vitamin B 12 (B 12 ) acts as a cofactor for two enzymes, methylmalonyl-CoA mutase and methionine synthase. Adenosylcobalamin is required for methylmalonyl-CoA mutase, which catalyzes a reaction that interconverts succinyl-CoA and methylmalonylCoA. Dysfunction of methylmalonyl-CoA mutase causes methylmalonic aciduria. Methylcobalamin (MeB 12 ) binding to methionine synthase serves as an intermediary in methyl transfer from methyltetrahydrofolate to homocysteine, donating the methyl group to homocysteine to form methionine, and then accepting a methyl group from methyltetrahydrofolate to form tetrahydrofolate. Methionine synthase is important both to resynthesize methionine and to metabolize methyltetrahydrofolate. Tetrahydrofolate accepts C1-groups from serine or formate. Then, the C1-group can be donated to either homocysteine to form methionine or deoxyuridine monophosphate to form deoxythymidine monophosphate. The C1-group also is precursor in de novo purine biosynthesis. Methionine is one of the amino acids that are building blocks for protein. In addition, methionine is activated to S -adenosylmethionine (AdoMet), which is well known as a major methyldonor for numerous substrates and an allosteric regulator for methylenetetrahydrofolate reductase (MTHFR) and cystathionine-␤ -synthase. While causal of symptoms related with dysfunction of methionine synthase, such as megaloblastic anemia and neuropathy, might be explained by the "Methyl trap" hypothesis ( 1-4 ), the biochemical mechanism has not yet been fully understoo...

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Section: Discussionmentioning

confidence: 52%

Section: Testicular Injury To Rats Fed On Soybean Protein-based Vitammentioning

confidence: 81%

Testicular Injury to Rats Fed on Soybean Protein-Based Vitamin B12-Deficient Diet Can Be Reduced by Methionine Supplementation

Yamada

Kawata

Wada

et al. 2007

J Nutr Sci Vitaminol

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“…It would appear that inhalatory anesthetics might be responsible for all these fertility problems. Several studies have been conducted on the effects of inhalatory anesthetics on sexual behavior and sperm motility [3,6,9,17,22,24]. However, little is known about the effect of new generation inhalatory anesthetics (sevoflurane and isoflurane) on spermatogenesis and sperm morphology.…”

Section: Introductionmentioning

confidence: 99%

Effects of Exposure to New Inhalational Anesthetics on Spermatogenesis and Sperm Morphology in Rabbits

Ceyhan

Cıncık

Bedir

et al. 2005

Archives of Andrology

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& The effects of chronic exposure to new inhalation anesthetics (sevoflurane and isoflurane) on spermatogenesis and sperm morphology were examined in 23 rabbits, randomly divided in 3 groups. Rabbits received 20 exposure hours (four hours=day Â 5 days), as follows: group I: 2.3% (1.2 MAC) sevoflurane þ 2L=min oxygen, group II: 1.3% (1.2 MAC) isoflurane þ 2L=min oxygen, and group III (control): 2L=min oxygen. Semen was collected on the 12th, 19th, 26th, 33rd, and 41st days of exposure. Sperm concentration, motility and morphological changes were evaluated. On the 41st day, testicular biopsies were taken and observed with light microscopy. Sperm concentration and motility significantly decreased in the sevoflurane and the isoflurane groups, compared to control. There were no significant changes in the control group. It is concluded that chronic exposure to the new inhalational anesthetics had negative effects on spermatogenesis and sperm morphology.

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“…N20 has been shown to cause neutropenia in rats (13)(14)(15)(16) and to inhibit the growth of malignant mouse (17), and normal (18) and malignant (19)(20)(21) human cells. Chronic exposure to N20 can cause a peripheral neuropathy in humans (22)(23)(24), and an increased incidence of birth defects in rats (25) and in humans (26)(27)(28).…”

mentioning

confidence: 99%

Nitrous oxide has multiple deleterious effects on cobalamin metabolism and causes decreases in activities of both mammalian cobalamin-dependent enzymes in rats.

Kondo¹,

Osborne²,

Kolhouse³

et al. 1981

J. Clin. Invest.

193

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Testicular Reaction to Prolonged Exposure to Nitrous Oxide

Cited by 44 publications

References 0 publications

Testicular Injury to Rats Fed on Soybean Protein-Based Vitamin B12-Deficient Diet Can Be Reduced by Methionine Supplementation

Testicular Injury to Rats Fed on Soybean Protein-Based Vitamin B12-Deficient Diet Can Be Reduced by Methionine Supplementation

Effects of Exposure to New Inhalational Anesthetics on Spermatogenesis and Sperm Morphology in Rabbits

Nitrous oxide has multiple deleterious effects on cobalamin metabolism and causes decreases in activities of both mammalian cobalamin-dependent enzymes in rats.

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