Temporal evaluation of c-fos expression in amygdaloid and hypothalamic areas following experimental tooth movement in rats
In the accomplishment of the orthodontic treatment, it is described that the pain happens immediately after the application of orthodontic forces and disappears after few days. Regarding the neural pathways involved in the sensorial mediation of the orthodontic movement (OM) few are the studies that approach this theme, and in the last decades solid founds demonstrate the involvement of the trigeminal system as well as its projection areas in this mediation. In this context, discoveries demonstrate that besides brainstem areas, such as periaquedutal gray matter, trigeminal spinal nucleus, and parabrachial area, limbic areas can present increase in FOS immunorreactivity(IR-FOS) 24 hours after the beginning of the tooth movement of rat molars. It is possible that this limbic activation happens due to the local liberation of prostaglandins. In this way, this work evaluated the activation of the central amygdala (CEA) and the lateral hypothalamus (LH) after OM. In addition, we verified if the previous administration of sodium diclofenac (painkiller and anti-inflammatory) or of morphine sulfate (painkiller of central action) alters IR-FOS after the application of force for tooth movement of rat superior incisors, in the analyzed limbic areas. Our results show that the OM increased the IR-FOS in CEA and in HL after 3, 6 and 24hs. After the OM for 48hs, the IR-FOS was similar to the control. The histological periodontal analysis of those animals evidenced an active process of bone remodeling, suggesting the deposition of osteoid material and the radiographic analysis demonstrated that the separation of the superior incisors of the animals happened due to the orthodontic movement and not orthopedic movement, since the interpremaxillary suture was fused. The pre-treatment with morphine sulfate (2mg/kg) inhibited the IR-FOS in both studied areas, suggesting that the expression of FOS after OM can be due to the transmission of nociceptive information. In addition, pre-treatment with sodium diclofenac (5mg/kg) reduced IR-FOS in CEA and in HL in the animals that received the orthodontic apparel for 6hs.
Advisor:Christie Ramos Andrade Leite Panissi; Jose Tarcisio Lima Ferreira; Patricia Maria de Paula; Christie Ramos Andrade Leite Panissi
School:Universidade de São Paulo
Source Type:Master's Thesis
Date of Publication:07/11/2008