Behavioral and physiological methods for early quantitative assessment of spinal cord injury and prognosis in rats

Abstract

Methods for reliable evaluation of spinal cord (SC) injury in rats at short periods (2 and 24 h) after lesion were tested to characterize the mechanisms implicated in primary SC damage. We measured the physiological changes occurring after several procedures for producing SC injury, with particular emphasis on sensorimotor functions. Segmental and suprasegmental reflexes were tested in 39 male Wistar rats weighing 250-300 g divided into three control groups that were subjected to a) anesthesia, b) dissection of soft prevertebral tissue, and c) laminectomy of the vertebral segments between T 10 and L 1 . In the lesion group the SC was completely transected, hemisected or subjected to vertebral compression. All animals were evaluated 2 and 24 h after the experimental procedure by the hind limb motility index, Bohlman motor score, open-field, hot-plate, tail flick, and paw compression tests. The locomotion scale proved to be less sensitive than the sensorimotor tests. A reduction in exploratory movements was detected in the animals 24 h after the procedures. The hot-plate was the most sensitive test for detecting sensorimotor deficiencies following light, moderate or severe SC injury. The most sensitive and simplest test of reflex function was the hot-plate. The hemisection model promoted reproducible moderate SC injury which allowed us to quantify the resulting behavior and analyze the evolution of the lesion and its consequences during the first 24 h after injury. We conclude that hemisection permitted the quantitation of behavioral responses for evaluation of the development of deficits after lesions. Hind limb evaluation scores and spontaneous exploration events provided a sensitive index of immediate injury effects after SC lesion at 2 and 24 h. Taken together, locomotion scales, open-field, and hot-plate tests represent reproducible, quantitatively sensitive methods for detecting functional deficiencies within short periods of time, indicating their potential for the study of cellular mechanisms of primary injury and repair after traumatic SC injury.

Antinociception of petroleum ether fraction derived from crude methanol extract of Melastoma malabathricum leaves and its possible mechanisms of action in animal models

“…The hot plate test is selective toward the centrally-acting analgesic drugs such as opioid analgesics (such as morphine) [47] and measures the complex feedback to a non-inflammatory, acute nociceptive input resulting from a brief exposure to a noxious thermal stimulus. In the present study, PEMM successfully attenuated the thermal-induced nociceptive effect suggesting the extract ability to inhibit the central nociceptive center.…”

Effect of melatonin on the functional recovery from experimental traumatic compression of the spinal cord

“…Rearing on the hind limbs involves primarily individual limbs 20. While just qualitative observations of locomotion are not sufficiently sensitive to assess the pattern of locomotion deficit 18, exploratory activity, rearing and grooming events are sensitive parameters for the detection of sensorimotor deficiencies 10. In summary, the results of the present study indicate that spinal cord injury produces a decrease in spontaneous locomotor activity as measured in an open-field test in spite of melatonin treatment.…”

“…Animals were anesthetized with an intraperitoneal ( ip ) injection of 250 mg/kg 2,2,2-tribromoethanol (Aldrich Chemical Company, USA), followed by subcutaneous administration of penicillin. After shaving the skin, animals were kept in a stereotaxic apparatus (David Kopf, USA) and a posterior incision in the skin and underlying muscles was made in the mid-thoracic region 10. Muscles were retracted and a mid-thoracic total laminectomy was performed at the level of the T10 vertebra.…”

Methods for behavioral testing of spinal cord injured rats

“…A progressive weight is then applied and the test stopped when the animal performs any movement of the paw or when the weight reaches a maximum, cut-off level. The force at which the rat withdraws its hindpaw is noted, multiplied by 10, and the withdrawal force in grams is thus obtained (Randall and Selitto, 1957;Giglio et al, 2006).…”