31P Magnetic resonance spectroscopyによるラット精巣機能の評価法の検討

Abstract

精巣の血流遮断と解除, 放射線照射, およびホルモン投与の3つの条件下で31P MRSを測定した。1)血流遮断後, ATPはすみやかに減少し60分以内に完全に消失した。2) 3時間までの血流遮断では遮断解除後にATPの回復が認められたが, 4時間以上の遮断では解除後もATPの回復は認められなかった。3)放射線照射2週間後ではPME/β-ATP比およびPME/PDE比の減少が認められ, PMEの減少は造精機能障害の指標として有用と考えられた。4)ホルモン投与によるgonadotropin抑制モデルでは, PME/PDE比の減少とPDE/β-ATPの増加を認め, PDEの増加も造精機能障害の第二の指標となりうる

To evaluate the efficacy of 31P magnetic resonance spectroscopy (31P MRS) as a diagnostic method for abnormal testicular function, we examined three conditions using rat testes, ischemia, irradiation, and hormone manipulation. 1) Ischemia: Immediately after clamping of the feeding vessels, ATP signals began to fall and disappeared within 60 minutes. With the release of blood supply after 3 hours of ischemia, ATP appeared within 2 hours. However, after more than 4 hours of ischemia, ATP did not recover within 2 hours and the testis became necrotic after 1 week. 2) Irradiation: 31P MRS of the testis 2 weeks after irradiation with 10 Gy., 9 MeV showed a significant decrease (P < 0.05) in the PME/beta-ATP ratio from 1.30 +/- 0.11 (control level) to 1.11 +/- 0.12 and a decrease in PME/PDE ratio from 1.43 +/- 0.17 to 1.13 +/- 0.20. However 3 weeks later, the PME/beta-ATP ratio recovered to a control level. 3) Hormone manipulation: In the testes 5 weeks after weekly intramuscular injections of estradiol benzoate and testosterone enanthate, PDE/beta-ATP ratio significantly increased (P < 0.01) from 0.83 +/- 0.09 (control level) to 1.03 +/- 0.19. 31P MRS is a non-invasive method for evaluation of various testicular abnormalities, and ATP signals may be useful to evaluate an acute ischemic change for example testicular torstion and the changes of PME, PDE signals may be useful parameters in the assessment of the status of spermatogenesis.