C-kit ligand (Stem Cell Factor) affects neuronal activity, stimulates pituitary-adrenal axis and prolactin secretion...

Stem Cell Factor (SCF) is a potent growth factor affecting proliferation, differentiation and migration as well as secretory functions of various cells of different origin and function. The effect of SCF on neuronal activity and on neuroendocrine regulation has been studied by injecting SCF i.v. into conscious male rats. Administration of SCF elevated adrenocorticotropin (ACTH), corticosterone and prolactin (PRL) plasma levels in a dose-dependent manner. Adrenocorticotropin and corticosterone secretions were maximal after injecting 10 micrograms SCF, while prolactin secretion only reached a maximum at a dose of 20 micrograms. Hormone secretions were maximal at 15 min (ACTH and PRL) or at 30 min (CORT) and declined to the baseline between 90 and 180 min. The functional anatomical approach, using immediate-early gene product c-Fos as a marker of activated neurones, revealed that systemic administration of SCF activated neurosecretory neurones of the hypothalamus in a time-dependent manner. Somatosensory afferent pathways and extrahypothalamic areas--which are involved in the regulation of hypothalamic neurosecretory cells--including various parts of the lamina terminalis, bed nucleus of stria terminalis, central amygdala, locus coeruleus, parabrachial nucleus, nucleus of the solitary tract and ventrolateral medulla also became Fos-positive. As SCF-induced mediators have been suggested to be involved in brain pathophysiology, and as SCF might have been of potential therapeutic use in certain anaemias and leukaemias, the complex interaction between SCF-induced cell-specific actions and its effect on the neuroendocrine system should also be considered.