Effect of electrophysical resources on healing of neurotendinous injury in an experimental model of type I diabetes and kidney disease

Abstract

Purpose: To evaluate and describe the effect of electrophysical resources laser therapy (LLLT), intravascular laser blood irradiation (ILIB), and cryotherapy on the healing process of neurotendinous injury, as well as possible systemic changes, in the experimental model of type 1 diabetes associated with kidney injury.

Methods: The animals were randomized into four groups: G1) healthy control with untreated injury; G2) healthy control with injury and treatment; G3) disease control with untreated lesion; G4) disease with injury and treatment. Furthermore, the treated groups were divided into three, according to the type of treatment. All animals were induced to neurotendinous injury and treated according to the therapeutic protocols. Healing and inflammation were analyzed by semiquantitative histopathological study.

Results: It was observed in sick animals treated with cryotherapy and ILIB reduction of inflammatory exudate, presence of fibroblasts and organization of collagen, when compared to the effects of LLLT. Moreover, there was reduction in glycemic levels in the group treated with ILIB.

Conclusions: Cryotherapy promoted reduction in inflammatory exudate and organization of collagen fibers, in addition to the absence of signs of tissue necrosis, in the groups treated with and without the disease. ILIB therapy showed the same findings associated with significant reduction in glycemic levels in the group of diseased animals. The application of LLLT showed increased inflammatory exudate, low organization of collagen fibers and low sign of tissue degeneration and necrosis. This study in a model of associated diseases (diabetes and kidney disease) whose effects of electrophysical resources studied after neurotendinous injury allows us to verify histopathological variables suggestive of patients with the same comorbidities.

Figure 1. Flowchart of the distribution of animals in groups and protocols. The flowchart shows the random division of animals into groups: G1 (healthy control with untreated injury); G2 (healthy control with injury and treatment), subdivided into subgroups L (low-level laser therapy treatment), I (intravascular laser irradiation of blood treatment), and C (cryotherapy treatment); G3 (disease control with untreated lesion); G4 (disease with injury and treatment), subdivided into subgroups L (low-level laser therapy treatment), I (intravascular laser irradiation of blood treatment), and C (cryotherapy treatment). While the timeline illustrates the phases of the experiment: acclimatization period (seven days), kidney disease induction (14 days), glucose monitoring (21 days), induction of the streptozotocin type I diabetes protocol (21 days), glucose monitoring (28 days), neurotendinous injury protocol (29 days), five days of consecutive treatment, and glucose monitoring and glucose monitoring, before euthanasia (35 days).

Figure 2. Compression of local left hind limb structures (tibial nerve and common calcaneal tendon). (a) Containment. (b) Local region compressed by the forceps.

Figure 3. Irradiation with low intensity laser therapy. (a) Parameter of energy and application. (b) – Direct punctual application. Parameters: 808 nm, continuous, 30 seconds, 100 mW, 3 J/cm², 3 J, 1 cm² area.

Figure 4. Intravascular blood irradiation with laser. (a) Therapeutic laser equipment. (b) Direct punctual application in the femoral artery. Parameters: 660 nm, continuous, 360 seconds, 100 mW, 36 J/cm², 36 J, 1 cm² area.

Figure 5. Immersion cryotherapy. (a) Average temperature 8-10°C. (b) Animal submitted to thecryotherapy protocol.

Figure 6. (a) (G2C): Photomicrograph of a tendinous segment showing the presence of fibroblasts (arrows) in dense modeled connective tissue. (b) (G1): Tendon segment also showing fibroblast nuclei (arrows), dense connective tissue sheath (star) and areas of degeneration (asterisks). (c) (G2L) and (d) (G2I): Tendon segments showing area of mononuclear inflammatory infiltrate (star) and fibroblast nuclei (arrows). 40x magnification, hematoxylin and eosin staining.

Figure 7. Comparisons between groups: analysis of variance of one-way repeated measures, with Tukey’s post-test. Representation of the semiquantitative analysis of the sections of the anatomopathological parts of the groups (G1, G2C, G2L and G2I). G2C presented better statistically significant results in relation to G1, G2L and G2I, illustrated by the star symbol. Results are presented as mean ± standard deviation of mean.

Figure 8. (a) (G4C): Photomicrograph of a tendon segment showing the presence of fibroblasts (arrows) in dense patterned connective tissue and an area of peritendinous inflammatory infiltrate (star). (b) (G4L): Tendon segment also showing fibroblast nuclei (arrows) and area of peritendinous inflammatory infiltrate (star). (c) (G4I) Tendon segment with lower intensity of inflammatory cells (star). (d) (G3): Tendon segments showing area of mononuclear inflammatory infiltrate (star) and fibroblast nuclei (arrows). 40x magnification, hematoxylin and eosin coloring.

Figure 9. Comparisons between groups: analysis of variance of one-way repeated measures, with Tukey’s post-test. Representation of the semiquantitative analysis of the sections of the anatomopathological parts of the groups (G3, G4C, G4L and G4I). G4I presented better statistically significant results in relation to G3, G4C and G4L, illustrated by the star symbol. Results are presented as mean ± standard deviation of mean.