Microscopic evidences that bone marrow mononuclear cell treatment improves sciatic nerve regeneration after neurorrhaphy.

Cell therapy constitutes a possibility for improving nerve regeneration, increasing the success of nerve repair. We evaluate the use of mononuclear cells in the regeneration of the sciatic nerve after axotomy followed by end-to-end neurorrhaphy. Forty adult male Wistar rats (250-300 g) were divided into four groups: (1) sham, (2) neurorrhaphy: the sciatic nerve was sectioned and repaired using epineural sutures, (3) culture medium: after the suture, received an injection of 10 µL of culture medium into the nerve, and (4) mononuclear cell: after the suture, a concentration of 3 × 10(6) of mononuclear cell was injected in epineurium region. Mononuclear cells were obtained from the bone marrow aspirates and separated by Ficoll-Hypaque method. The histological analyses were performed at the 4th postoperative day. The sciatic functional index, histological, and morphometric analyzes were used to evaluate nerve regeneration at the 6th postoperative week. Six rats were used for immunohistochemical analysis on the 4th postoperative day. In the group 4, on the fourth day, the histological analysis demonstrated a more accelerated degenerative process and an increase of the neurotrophic factors was observed. In the 6th week, all the morphometric results of the group 4 were statistically better compared with groups 2 and 3. There was a statistically significant improvement in the sciatic functional index for group 4 compared with groups 2 and 3. Mononuclear cells stimulated nerve regeneration, most probably by speeding up the Wallerian degeneration process as well as stimulating the synthesis of neurotrophic factors.

Ultrasonic rat vocalizations during the formalin test: a measure of the affective dimension of pain?

The emission of ultrasonic vocalization (USV) by rats submitted to the formalin test has not yet been demonstrated. We performed two experiments to establish the formalin concentration to induce USV and the relationship of USV emission with motor behaviors and the effects of morphine and naloxone on USV during the formalin test. Male Wistar rats were used. In Experiment 1, 3 different groups of rats were subcutaneously injected with 5%, 10%, or 12.5% formalin in 1 of the anterior paws. Experiment 2 was intended to verify the effect of morphine 1, 2.5, or 5 mg/kg on USV during the 12.5% formalin test, whereas other groups of rats received naloxone 2 mg/kg with each one of the morphine doses to verify the specificity of opioid action. USV and motor behaviors were simultaneously measured in 5-min windows for 40 min, and early (0-5 min), interphase (5-20 min), and late (20-40 min) phases of the test were characterized. Vocalization was detected mostly during the interphase of the formalin test, mainly after formalin 12.5%. Morphine suppressed USV in a naloxone-reversible manner. This is a demonstration of USV during the formalin test, allowing the inclusion of an additional nonreflex behavioral measure to help characterize more clinically relevant integrated behavioral patterns in this rat model of pain.