Galanin-like immunoreactive nerve fibres in the anterior pituitary of the normal and adrenalectomized rat.

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