Surgical pinealectomy accelerates intervertebral disc degeneration process in chicken

Despite the importance of intervertebral disc (IVD) degeneration both in research and clinical practice, the underlying biological mechanism of this phenomenon remains obscure. The current study investigated the effects of neonatal pinealectomy on the development of IVD degeneration process in chicken. Thirty chicks (3 days of age) were divided into two equal groups: unoperated controls (Group X) and pinealectomized chicks (Group Y). Pinealectomies were performed at the age of 3 days. At the age of 8 weeks, magnetic resonance imaging examination of one animal in each experimental group was taken. At the end of the study, serum melatonin level was determined by using ELISA method and histopathological or biochemical examination of specimens from all subjects was done. The results of biochemical analyses were compared using Mann-Whitney U test, whereas The Chi-square test was adopted for the histological findings. In this study, the serum melatonin levels in Group Y were significantly lower than those in Group X (P < 0.001). Similarly, scoliosis was developed in 14 out of 15 (93%) in Group Y. Hydroxyproline content of IVD tissue was high in Group Y compared with the values in Group X, although there was no significant difference. Histologically, an appearance of normal IVD was observed in Group X, while the presence of a degenerated IVD was observed in Group Y. From the results of the current study, it is evident that surgical pinealectomy in new-hatched Hybro Broiler chicks has a significant effect on serum melatonin level as well as on the development of IVD degeneration and spinal malformation. In the light of these results from present animal study, melatonin may play a role in the development of IVD degeneration in human beings, but this suggestion need to be validated in the human setting.