Effect of radiofrequency on patellar ligament repair of Wistar rats.

This study aimed to evaluate the effects of radiofrequency (RF) on patellar ligament repair through the analysis of type I and III collagens and immunostaining for TGF-ß3. To evaluate the effect of RF on patellar ligament repair of Wistar rats, cross-sectional incision (60% of the width - grade I) was performed in patellar ligaments of the groups: lesion (L, n = 7), treated with RF on the 5-day (5RF, n = 7) and 7-day (7RF, n = 7) post injury were compared to control group (C, n = 7). Histological evaluation, immunohistochemistry, morphometry and statistical analysis were performed. At 10 days post injury, ligament rupture were observed only in L. Active fibroblasts, type 3 collagen and TGF-ß3 in L, 5RF and 7RF was significantly (p < 0.05) higher than control (C). Type 1 collagen was significantly (p < 0.05) higher in C than L, 5RF and 7RF. A positive correlation (p < 0.05) was observed: TGF-ß3 vs active fibroblasts and TGF-ß3 vs type 3 collagen; otherwise, negative correlation (p < 0.05): type I collagen vs TGF-ß3. These results suggest that RF seemed to accelerate the wound healing process of the patellar ligament and may be used as a non-invasive treatment of partial ligament injuries.

Environmental novelty modulates the induction and expression of single injection-induced behavioral sensitization to morphine.

Opioid addiction is a growing public health problem, being currently considered an epidemic in the United States. Investigating the behavioral effects of opioids and the factors influencing their development becomes of major importance. In animals, the effects of drugs of abuse can be assessed using the behavioral sensitization model, which shares similar neuronal substrates with drug craving in humans. Importantly, novelty plays a critical role on the development of behavioral sensitization. The aim of the present study was to investigate the influence of a new environment on both the induction and expression phases of morphine (Mor)-induced behavioral sensitization in the two-injection protocol. Mice were initially treated with saline, 15 or 30 mg/kg Mor (induction phase), and subsequently challenged 7 days later with 15 mg/Kg Mor (expression phase). Locomotor frequency was evaluated during behavioral sessions, performed as follow: induction session on a novel environment and expression on a familiar open-filed apparatus; induction session on animals' home-cage (familiar environment) and expression session on an unknown open-filed apparatus; both sessions on novel environments; and both sessions on familiar contexts. Mor-induced behavioral sensitization was only observed when animals were exclusively exposed to novelty during the induction phase, not being observed when both the induction and expression sessions were performed on similar (novel or familiar) environments. Our results suggest that the development of behavioral sensitization to Mor depends on the exposure to novelty during the induction phase and absence of novelty during the expression phase, indicating a complex relationship between novelty and Mor-induced behavioral effects.

Depressive behavior induced by social isolation of predisposed female rats.

Depression is a mood disorder that is more prevalent in women and has been closely associated with chronic stress. Many models of depression have been suggested that consider different forms of stress. In fact, stress is present in the life of every human being, but only a few develop depression. Accordingly, it seems wrong to consider all stressed animals to be depressed, emphasizing the importance of predisposition for this mood disorder. Based on this finding, we evaluated a predisposition to depressive behavior of female rats on the forced swim test (FST), and the more immobile the animal was during the FST, the more predisposed to depression it was considered to be. Then, animals were subjected to the stress of social isolation for 21 days and were re-evaluated by the FST. The Predisposed/Isolated rats presented higher immobility times. Once all the rats had prior experience in the FST, we calculated an Index of Increase by Isolation, confirming the previous results. Based on this result, we considered the Predisposed/Isolated group as presenting depressive behavior ('Depressed') and the Nonpredisposed/Nonisolated group as the control group ('Nondepressed'). The animals were distributed into 4 new groups: Nondepressed/Vehicle, Nondepressed/Amitriptyline, Depressed/Vehicle, Depressed/Amitriptyline. After 21 days of treatment, only the Depressed/Vehicle group differed from the other 3 groups, demonstrating the efficacy of amitriptyline in treating the depressive behavior of the Depressed animals, validating the model. This study shows that conducting an FST prior to any manipulation can predict predisposition to depressive behavior in female rats and that the social isolation of predisposed animals for 21 days is effective in inducing depressive behavior. This behavior can be considered real depressive behavior because it takes into account predisposition, chronic mild stress, and the prevalent gender.