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Local NO synthase inhibition produces histological and functional recovery in Achilles tendon of rats after tenotomy

Tendon repair and local NOS inhibition


Repair of injured tendon is a very slow process and involves the release of many molecules, including nitric oxide. We investigate the influence of local nitrergic inhibition in histological and functional recovery of injured Achilles tendon. A standard murine model of tendon injury by rupture was used. The animals were divided into three experimental groups: control, injury + vehicle (normal saline) and injury + Nω-nitro-L-arginine methyl ester (L-NAME). The products were injected into the paratendinous region every 2 days and body weight gain and Achilles functional index (AFI) were evaluated on days 0, 7, 14 and 21 after tendon injury. On day 21 post-injury, the animals were killed to evaluate nitric oxide production and tissue organization. We observed that tendon surgical division led to increased tissue nitrite levels, which were reduced in L-NAME-treated rats. The AFI revealed functional recovery of L-NAME-treated animals on day 21 post-injury, which was not observed in the saline-treated group. Microscopic analysis of hematoxylin-eosin staining and collagen autofluorescence showed that L-NAME-treated rats had more aligned areas of collagen fibers and that the diameter of newly organized collagen in this group was also greater than that in the vehicle-treated one. We demonstrate that local treatment with L-NAME significantly improves the functional parameters and accelerates histomorphological recovery.

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Correspondence to Anderson M. Herculano.

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Moraes, S.A.S., Oliveira, K.R.M., Crespo-López, M.E. et al. Local NO synthase inhibition produces histological and functional recovery in Achilles tendon of rats after tenotomy. Cell Tissue Res 353, 457–463 (2013).

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  • Tendon injury
  • Nitric oxide
  • Tendon healing
  • Nitric oxide synthase
  • Wound healing