Role of serotonin for scoliotic deformity in pinealectomized chicken

Study Design. The effect of intraperitoneal injection of 5-hydroxytryptophan (5-HTP) versus control in pinealectomized chickens. Objective. To find if the serotonin may have some role in the cause or treatment of idiopathic scoliosis. Summary of Background Data. One of the causes of idiopathic scoliosis is thought to be the disruption of postural reflex. Serotonin has been proposed to have a crucial role in maintaining normal postural muscle tone or postural equilibrium. Method. Forty pinealectomized chickens served as controls, and an additional 40 pinealectomized chickens received daily intraperitoneal injections of 5-hydroxytryptophan, a precursor of serotonin, which can pass through the blood-brain barrier. Spine radiographs were examined to measure the scoliotic deformity. Results. Scoliosis developed in all 40 pinealectomized chickens (control), whereas only 28 chickens in the 5-hydroxytryptophan-treated group (6 in severe, 22 in mild) had scoliosis developed. The remaining 12 chickens grew up with normal spines. Mast chickens with mild scoliosis did not have curve progression but continued to have wedged vertebrae. Conclusion. Serotonin deficit secondary to a defect of melatonin may have disturbed postural muscle tone or postural equilibrium resulting in scoliosis in pinealectomized chicken. Prevention from the development of scoliosis or its progression in chickens treated with 5-hydroxytryptophan suggests that serotonin may have potential therapeutic value.