ABSTRACT
The objective of the present study was to determine the antihyperalgesic effect of sertraline, measured indirectly by the changes of sciatic afferent nerve activity, and its effects on cardiorespiratory parameters, using the model of formalin-induced inflammatory nociception in anesthetized rats. Serum serotonin (5-HT) levels were measured in order to test their correlation with the analgesic effect. Male Wistar rats (250-300 g) were divided into 4 groups (N = 8/per group): sertraline-treated group (Sert + Saline (Sal) and Sert + Formalin (Form); 3 mg·kg-1·day-1, ip, for 7 days) and saline-treated group (Sal + Sal and Sal + Form). The rats were injected with 5 percent (50 µL) formalin or saline into the right hind paw. Sciatic nerve activity was recorded using a silver electrode connected to a NeuroLog apparatus, and cardiopulmonary parameters (mean arterial pressure, heart rate and respiratory frequency), assessed after arterial cannulation and tracheotomy, were monitored using a Data Acquisition System. Blood samples were collected from the animals and serum 5-HT levels were determined by ELISA. Formalin injection induced the following changes: sciatic afferent nerve activity (+50.8 ± 14.7 percent), mean arterial pressure (+1.4 ± 3 mmHg), heart rate (+13 ± 6.8 bpm), respiratory frequency (+4.6 ± 5 cpm) and serum 5-HT increased to 1162 ± 124.6 ng/mL. Treatment with sertraline significantly reduced all these parameters (respectively: +19.8 ± 6.9 percent, -3.3 ± 2 mmHg, -13.1 ± 10.8 bpm, -9.8 ± 5.7 cpm) and serum 5-HT level dropped to 634 ± 69 ng/mL (P < 0.05). These results suggest that sertraline plays an analgesic role in formalin-induced nociception probably through a serotonergic mechanism.
Subject(s)
Animals , Male , Rats , Formaldehyde/antagonists & inhibitors , Nociception/drug effects , Selective Serotonin Reuptake Inhibitors/pharmacology , Sertraline/pharmacology , Arterial Pressure/drug effects , Formaldehyde/pharmacology , Heart Rate/drug effects , Neurons, Afferent/drug effects , Pain Measurement/drug effects , Rats, Wistar , Respiratory Rate/drug effects , Sciatic Nerve/drug effects , Serotonin/bloodABSTRACT
The anti-inflammatory activity of a purified fraction of the rhizome of Wilbrandia (cf) verticillata, which contains two novel norcucurbitacin glucosides, is reported. The increase of vascular permeability induced by acetic acid in mice (N = 5) was inhibited 69% and 90% by 50 and 100 mg/kg of the purified fraction, po (P<0.01). Acetylsalicylic acid (200 mg/kg), po, inhibited the response by 62% under the same conditions (P<0.05). The purified fraction (100 mg/kg, po) also significantly inhibited paw swelling in the rat formaldehyde-induced arthritis model on 8 of 10 days and reduced the swelling by 63% on day 10. Dexamethasone (1 mg/kg, ip) was more effective than the extract under the same conditions. These data partially characterize the anti-inflammatory activity of the purified fraction from this plant which is used in Brazilian folk medicine for the treatment of arthritis and related disorders