Changes in serum melatonin levels in response to pinealectomy in the chicken and its correlation with development of scoliosis

Study Design. Normal, sham, and groups of chickens subjected to pinealectomy from which serum melatonin levels were measured and correlated with scoliosis development in a period of 5 weeks. Objectives. To measure serum melatonin levels in chickens subjected to pinealectomy and control chickens and correlate findings with development of scoliosis. Summary of Background Data. In a previous study by others, scoliosis developed in 100% of chickens subjected to pinealectomy, and serum melatonin levels were found to be reduced. Previous results in a study by the authors showed scoliosis developing in only approximately 55% of chickens that underwent pinealectomy. Methods. Young chickens were subjected to pinealectomy. Control groups consisted of sham operation and normal groups. Radiographs and blood samples were taken at weekly intervals to monitor scoliosis development and measure serum melatonin levels using radioimmunoassay techniques. Results. Scoliosis developed in only 52% of chickens that underwent pinealectomy, but all had low levels of serum melatonin and no circadian rhythm. The chickens in the two control groups maintained normal serum melatonin levels and rhythms. Conclusions. Pinealectomy in young chickens reduces serum melatonin levels and eliminates the melatonin circadian rhythm. It can also produce scoliosis, but low levels of serum melatonin are a poor predictor of development of scoliosis.