The Study On The Expression Of Motilin In Human Thyroid And Clinical Significance

AIM: To research the expression and sequencing of motilin precursor mRNA in human thyroid;To explore the expression and location of motilin active peptide in human thyroid;And to study the expression of motilin and motilin precursor mRNA in human thyroid tumors and clinical significance.METHODS: In the current study, RT-PCR, Sourthern blot and molecular cloning were used to detect motilin transcripts expression in human thyroid, immunohistochemical techniques to investigate the cellular distribution of this peptide in human thyroid and tumours, and real-time PCR and immunohistochemical techniques to quantify motilin precursor mRNA and motilin peptide in different thyroid tissues (thyroid adenoma, medullar, follicular, papillary and nodular goiter).RESULTS: RT-PCR and Southern blot showed that motilin mRNA expressed in human thyroids was identical to that expressed in duodenum from Genbank in America. Immunohistochemical result showed there are many positive cells of motilin in human thyroid. Motilin was co-localized with Calcitonin (CT) in thyroid C cells. Thyroid carcinomas (thyroid medullar, acidophilic adenoma, follicular, papillary and nodular goiter) also showed intense and diffuse immunostaining for motilin. It has been shown that expression of motilin in thyroid medullar and acidophilic adenoma were significantly higher than those of normal thyroid tissue (P<0.001);The expression of motilin in thyroid follicular and papillary were significantly lower than those of normal thyroid tissue(P<0.01);However there is no difference between the thyroid nodular goiter and normal tissue(P>0.05). In Real-time PCR experiments, the expression of motilin precursor in thyroid medullar and acidophilic adenoma were significantly higher than those of normal thyroid tissue(P<0.01). The expression of motilin precursor mRNA in thyroid follicular and papillary were significantly lower than those of normal thyroid tissue(P<0.05);There is no difference between the thyroid nodular goiter and normal tissue(P>0.05).CONCLUSION: Motilin mRNA expressed in human thyroids was identical to that expressed in duodenum from Genbank in America. There are many positive cells of motilin in human thyroid. Motilin immunoreactivity was co-localized with Calcitonin. It suggests that motilin located in thyroid C cells. Thyroid carcinomas (thyroidmedullar, acidophilic adenoma,follicular, papillary and nodular goiter) also showed intense and diffuse immunostaining for motilin. The expressions of both motilin and motilin precursor mRNA in thyroid medullar and acidophilic adenoma were significantly higher than those of normal thyroid tissue. However the expressions of motilin and motilin precursor mRNA in thyroid follicular and papillary were significantly lower than those of normal thyroid tissue. These data suggest that motilin may well be acting in a paracrine fashion in the regulation of physiology. The motilin immunostaining found in the thyroid gland opens up the possibility of its secretion to the bloodstream or its involvement in the regulation of the thyroid function. Moreover we maybe provide the basis of medicine for the patient of affected thyroid medullary carcinoma.