Effect of neurotensin and substance P on adrenal cortex regeneration.

The influence of neurotensin (NT) and substance P (SP) on the early stage of adrenal regeneration was investigated. Neurotensin (5 and 50 micrograms/kg) and SP (10 and 100 micrograms/kg) were given to rats subjected to adrenal enucleation combined with contralateral adrenalectomy. The mitotic index was employed to assess cell growth, and plasma corticosterone was determined by a radioimmunological assay. The animals were killed 4 and 8 days after operation. Neurotensin did not evoke any significant changes either in the proliferation ratio or corticosterone production of regenerating adrenal cortex. However, it was found that SP (100 micrograms/kg) stimulated both the proliferation and steroidogenesis on the eighth day after operation.