Articles
Formalin test observation box
Features
- Observation boxes Made of durable and easy to clean Plexyglass™ plastic
- Base made of aluminum and glass
Specification
|
Base dimensions (HxWxD) |
60 cm X 30 cm X 40 cm |
|
Observation box dimensions (HxWxD) |
25 cm X 25 cm X 30 cm |
|
Mirror angle |
45º |
Definition
The formalin test in rats has been proposed as a chronic pain model which is sensitive to centrally active analgesic agents by Dubuisson and Dennis in 1977. Rats are administered 0.05 ml of 2-5% formalin (intradermally) into the dorsal portion of the front paw. Each individual rat is placed into plastic observation box for observation. Readings are taken at 30 and 60 min and scored according to a pain scale. Pain responses are indicated by elevation or favoring of the paw or excessive licking and biting of the paw. Analgesic response or protection is indicated if both paws are resting on the floor with no obvious favoring of the injected paw. The formalin test may allow dissociation between inflammatory and non-inflammatory pain, a rough classification of analgesics according to their site and their mechanism of action. The formalin-test is a model of chronic pain whereas most other methods measure only the effect on acute pain.
A biphasic response with an early (0–5 min) and a late (20–60 min) phase with high licking activity is observed. Central acting analgesics were active in both phases, whereas non-steroidal anti-inflammatory drugs and corticosteroids inhibited only the late phase. Acetylsalicylic acid and paracetamol were antinociceptive in both phases.