Analgesic, Anti-inflammatory and CNS Depressant Activities of the Methanolic Extract of Abelmoschus esculentus Linn. Seed in Mice.

Aims: The study was carried out to assess the analgesic, anti-inflammatory and CNS depressant activity of the methanolic extract of Abelmoschus esculentus Linn. Seeds. Study Design: The Present study was designed to observe pharmacological activities of the crude extract of the plant Abelmoschus esculentus seeds. The study consisted of hot extraction of the seeds of the A. esculantus with methanol. Afterwards, Methanolic crude extract was filtered and the filtrate was evaporated. Finally, screening of analgesic, antiinflammatory and CNS depressant activity of crude extracts of A. esculantus on Swiss Albino mice. Place and Duration of Study: Department of Pharmacy, Atish Dipankar University of Science and Technology, Dhaka, Bangladesh. January, 2013- July 2013. Methodology: The animals are divided into Four groups and each group consists of five mice. Analgesic activity was performed by acetic acid-induced writhing model and formalin induced licking and biting in mice. Anti-inflammatory effects of Abelmoschus esculentus seed extract were done by carrageenan induced anti-inflammatory method at the dose of 100 and 200 mg/kg b.wt., (p.o). The CNS depressant activity was evaluated by observing the reduction of locomotor and exploratory activities in the hole cross and opens field tests at the dose of 100 and 200 mg/kg body weight. Results: In statistical analysis, the dose (200 mg/kg) was found to exhibit (significant p=0.05) better analgesic activity (65.16% and 54.38%) against both acetic acid and formalin induced pain in mice which is about similar to standard drug Indomethacin. The extract of A. esculentus (100 and 200mg/kg) also showed sustained inhibition (54.97% and 65.56%) of paw edema at the 4th hour compared to Indomethacin (74.17%). Besides this A. esculentus (significant p=0.05) seed extract (100 and 200mg/kg p.o.) also possesses depressant activity at 90min in both methods. Conclusion: this study recommends that the methanolic extract of the Abelmoschus esculentus seeds has significant CNS depressant, analgesic and anti-inflammatory properties.

The effect of sciatic nerve injection of dexmedetomidine on the nociceptive behavior and spinal c-fos expression in formalin mice / 重庆医学

Objective To investigate the effect of sciatic nerve injection of dexmedetomidine on the nociceptive behavior and spi-nal c-fos expression in formalin mice .Methods Adult male Kunming mice ,20-25 g ,were divided into 4 groups randomly :mice in group A and D were given an injection of NS (10 μL) and 0 .1 μg dexmedetomidine in 10 μL adjacent to the right sciatic nerve , sepretely .Mice in group B received intacutaneous injection of 10μL formalin(5% ) in the right hindpaws .Mice in group C were giv-en an injection of 0 .1 μg dexmedetomidine in 10 μL adjacent to the right sciatic nerve 15 min before formalin injection in the right hindpaws .Paw licking/biting time was counted every 5 min for an hour after hindpaw injections ,calculated pain score .1 hour after behavior tests ,the L4-5 of spinal cord were harvested to immunofluorescence for c-fos expression in the dorsal corn of spinal cord . Results Mice in group A、C and D showed no obvious foot licking/biting behaviors and a low level of c-fos expression in the dorsal corn of spinal cord .Compared with group A ,mice in group B displayed obvious two phases foot licking/biting behaviors(P<0 .05 , both in Phase Ⅰ and Phase Ⅱ) and a significant increasing expression of c-fos(P<0 .05) .Compared with group B ,dexmedetomi-dine injected to the adjacent of right sciatic nerve decreased the pain score and spinal c-fos expression in goup C(P<0 .05) .Conclu-sion Injection of dexmedetomidine to the right sciatic nerve alleviated intraplantar injected formalin-induced acute inflammatory pain ,and reduced the expression of spinal c-fos protein .

Sertraline inhibits formalin-induced nociception and cardiovascular responses

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.

Antinociception induced by central administration of histamine in the formalin test in rats.

In the present study, effects of intracerebroventricular (icv) administration of histamine, mepyramine (H1-receptor antagonist) and famotidine (H2-receptor antagonist) have been investigated on the formalin test in rats. Subcutaneous injection of formalin (50 μl, 1%) into the ventral surface of the left hind paw produced a marked biphasic pain response (first phase: 0–5 min and second phase: 15–45 min). All the performed treatments did not significantly influence the first phase of pain. Histamine at the doses of 10 and 40 μg and mepyramine and famotidine at the same doses of 20 and 80 μg, significantly (P<0.05) decreased the late phase of formalin-induced pain. Pretreatments with mepyramine and famotidine at the same dose of 80 μg, significantly (P<0.05) prevented the histamine (40 μg)-induced antinociception. These results indicate that brain histamine produces antinociception, and both central H1 and H2 receptors may involve in the histamine-induced antinociception in the formalin test in rats.