Original Article
Spinal Cord advance online publication 23 June 2009; doi: 10.1038/sc.2009.73
Rhythms of serum melatonin in rats with acute spinal cord injury at the cervical and thoracic regions
A R Gezici1, A Karaka
2, R Ergün1 and B Gündüz3
- 1Department of Neurosurgery, Faculty of Medicine, Abant
zzet Baysal University, Bolu, Turkey - 2Department of Biology, Faculty of Arts and Sciences, Abant zzet Baysal University, Bolu, Turkey
- 3Department of Biology, Faculty of Arts and Sciences, Çanakkale Onsekiz Mart University, Çanakkale, Turkey
Correspondence: Dr AR Gezici, Department of Neurosurgery, Faculty of Medicine, Abant zzet Baysal University, Bekavaklar Mahallesi. Öznur Apartment, No: 16/8, Bolu 14300, Turkey. E-mail: geziciar@gmail.com
Received 18 December 2008; Revised 11 May 2009; Accepted 20 May 2009; Published online 23 June 2009.
Abstract
Objective:
To evaluate the serum melatonin levels in acute period of the spinal cord injury (SCI) caused by trauma in the rats.
Background:
Traumatic SCI induces many types of physiological and pathological damage, including hormonal level variations.
Methods:
Forty male Sprague–Dawley rats were divided randomly into four groups. In the control group, neither laminectomy nor SCI were performed; only a large laminectomy was performed without SCI in the sham group. In the cervical and thoracic spinal trauma groups, laminectomies at C5-6 and a T6-7 were performed, respectively, followed by clip compression of the spinal cord. Blood samples were drawn 2, 6, 12 and 24 h after the procedures and assayed immediately.
Results:
The levels of melatonin in the neurotrauma groups were high in the first 2 h, but at the end of sixth hour, melatonin levels increased in sham-operated group, decreased in neurotrauma groups and did not change in control group. At the 12th hour, melatonin levels continued to decrease in thoracic group significantly. At the 24th hour, the melatonin levels decreased in the cervical, control and sham groups, whereas melatonin levels increased in the thoracic group.
Conclusions:
The present study revealed that (1) activation of endogen melatonin secretion of the organism starts immediately after the SCI, but it shows a great lowering trend between 2 and 6 h post-SCI, (2) the tetraplegic rats, which had complete injuries at the lower cervical spinal cord, could not produce enough melatonin secretion; on the contrary, the paraplegic rats, which had complete injury at the upper thoracic spinal cord, showed normal melatonin secretion.
Keywords:
melatonin, neuroprotection, spinal cord injury
