GALANIN-LIKE IMMUNOREACTIVE NERVE-FIBERS IN THE ANTERIOR-PITUITARY OFTHE NORMAL AND ADRENALECTOMIZED RAT

Our previous studies have shown the presence of substantial amounts of substance P and calcitonin gene-related peptide-like immunoreactive n erve fibres in the anterior pituitary of the monkey, dog and rat. Furt hermore, synaptic relationships have been demonstrated between these n erve fibres and the gland cells in the dog and rat. The substance P an d calcitonin gene-related nerve fibres increase in number following ad renalectomy and ovariectomy, respectively. The present study was aimed to investigate the galanin-containing nerve fibres in the anterior pi tuitary of normal and adrenalectomized rats. The results showed only a small amount of galanin-like immunoreactive nerve fibres in the norma l anterior pituitary, which were present among the gland cells as well as along the blood vessels. Following adrenalectomy, the number of ga lanin-like immunoreactive nerve fibres increased and ramification appe ared more frequently. The results substantiate our hypothesis of a dua l neural-humoral regulation of the mammalian anterior pituitary gland.