The spinal cord, which connects the brain and the peripheral nervous system, contains millions of neurons responsible for sending information throughout the body. Included in these nerve cells are those for balance and movement. When the spinal cord is injured, the organism may suffer paralysis and recovery from this can be aided by nerve growth factors also called neutrophins. This study aims to demonstrate the effect of spinal cord transection to test animals and the recovery of these animals with the aid of neutrophins (Coumans, et al.).
Spinal cord transection was done using the procedures of Bregman and McAtee (1993) except that the tissue transplantation part was not performed. The test organisms are adult female rats, around 6-8 weeks old, with a weight of 200-250 grams before surgery. The spinal cord was transected with iridectomy scissors. Neutrophin was then administered to the animals subcutaneously. A gel foam soaked in saline solution was placed on top of the transplanted tissue and the muscle and skin covering the transection area were stitched back in place. Ten rats were used in this set-up. For comparative purposes, ten rats were subjected into the same transection surgery procedure, but were not given neutrophins. Ten rats were used as a control, which did not undergo transection and neutrophin administration. The 30 rats were given 20 cc/d of D5 lactated Ringer’s solution for hydration. The test animals were given antibiotics [sulfamethoxazole (4 mg/100 gm)-trimethoprim (0.8 mg/100 gm)] to prevent infection. They were also given food and water inside their cages. The locomotor behavior of the animals was observed to determine the recovery of their spinal cord after the injury (Coumans et al., 2001).
Behavior of the test animals which were subjected to transection only, transection with neutrophin administration, and not subjected to both transection and neutrophin administration (control) were observed and recorded. Observation of movement and locomotor functions to determine the recovery of the rats were started right after the surgical procedure. The results agreed with those of Coumans et al. (2001). All the rats exhibited no voluntary movement of their hind limbs while taking steps. The animals dragged their extended hind limbs passively while being supported by their forelimbs. However, their locomotion functions started to vary 3 to 4 weeks after the transection. The animals which received transection only did not show improvement of their hind limb function. On the other hand, those which received neutrophin together with trasnsection showed improvement of hind limb weight support, nearly showing a pattern similar to that of the control rats. The test animals’ limb movements were further observed using stairs. The control animals (C) showed full support of their weight using their limbs in each step. The animals which were subjected to transection only (T) dragged their hind limbs while climbing. Those which were subjected to transection and were also administered neutrophins (T+N) exhibited improved hind limb function, with their weight supported in each step while climbing (Fig. 1).
Fig. 1. Comparison of the mean total of steps with supported weight of the test animals. Control animals (C) showed 100% weight support, rats which received transection only (T) showed no weight support, and those which were transected and given neutrophins showed increased weight support in their steps.
T T+N C
In the experiment, rats were used as models as they provide consistency or results when it comes to spinal cord injuries (Adamson, 2000). Results show that the test animals were able to recover well with the aid of neutrophins. These also agree with the established fact that neutrophins are important requirements for the survival neurons. These neurons are especially developed in the vestibular ganglia. Since these neurons are located in the inner ear, they are of particular importance for the sense for motion and balance. Since neutrophins are nerve growth factors (NGFs), they help in the recovery of the injured spinal cord (Lodish, et al., 2000).
When the spinal cord is damaged, cytokines are induced in response to the damage. Together with this, growth factors which would function for recovery are also induced. One example is neutrophin, which aided the administered test animals to regain a considerable improvement in their locomotor functions. This would explain the poor recovery of the rats which were subjected only to transection and did not receive neutrophins. Since they are not given the growth factor, their neurons and spinal cord tissues did not improve after the injury promoted by the transection. As opposed to those which received neutrophins, their hind limbs did not heal enough to provide weight-supported steps (Friedman, 2000).
The improvement of locomotor functions of the hind limbs of the test rats can be correlated to the restoration of the neuron connections present in the spinal column. This restoration is further supported by the administered neutrophins (Coumans, 2001).
Results derived from this study as well as from other recent studies on neutrophin receptors, apoptosis, and spinal cord injury can provide mechanisms on how to prevent degeneration of neurons. This would aid in the discovery of therapeutic means to help an injured spinal cord recover (Friedman, 2000).