Trying out tramadol in rats

Zegre Cannon et al. evaluated the applicability of tramadol as a practical and effective analgesic in male Sprague Dawley rats. To measure the efficacy of four dosages and three routes of administration, they used the hot-plate test and the tail-flick test. The intraperitoneal route of administration was effective at dosages of 12.5 mg, 25 mg and 50 mg tramadol per kg body weight, though sedation was observed at dosages of 25 mg and 50 mg per kg body weight. There were no notable side effects after intraperitoneal administration of 12.5 mg tramadol per kg body weight. The authors plan to further study this dosage and route of administration in rodents.

See page 342

Long-term catheter placement

Research using rats sometimes requires long-term placement of catheters in the subarachnoid space, the cavity between the arachnoid mater and the pia mater in the brain. To date, published techniques for penetrating the subarachnoid space of small experimental animals require the use of inflexible or relatively inflexible catheters, which are not ideal for long-term placement in the subarachnoid space. Ehlert and colleagues describe a reliable procedure for long-term catheterization of the subarachnoid cavity of the rat. This new approach allows personnel to repeatedly use the catheter for a period of at least 2 weeks.

See page 352

Manipulation of light:dark cycles

Delaney and colleagues designed and built a device that can house mice or rats and allow researchers to control the light:dark cycles inside. The chamber, which (when closed) completely blocks outside light, contains two units. Each unit can hold eight small mouse cages or six rat cages and contains an optical sensor that triggers an audible and visual alarm when light is detected. Researchers have reported that this chamber is ideal for use in work involving manipulations of light:dark cycles.

See page 360