Hypophysiotrophic neurons are capable of altering the ratio of co-packaged neurohormones.
Neuronal dense-core vesicles provide a mechanism whereby peptide messengers are secreted in discrete quanta. Here we report on the capacity of rat hypophysiotrophic corticotropin releasing factor-41 neurons to alter the peptide content as well as the size of dense-core vesicles after removal of glucocorticoid negative feedback by adrenalectomy. We demonstrate, using quantitative immunoelectron microscopy, that long-term adrenalectomy induces a progressive increase in the ratio of vasopressin to corticotropin releasing factor-41-immunoreactive sites in the dense-core vesicle compartment. The intravesicular concentration of vasopressin appeared to be the variable parameter while that of the corticotropin releasing factor-41 remained stable at all survival times after adrenalectomy. Moreover, observations for up to 5 weeks indicate that adrenalectomy results in a progressive increase in the mean volume of dense-core vesicles to about three times normal. These results suggest that the quantal size and the composition of dense-core vesicles are subject to long-term modulation. The capacity of corticotropin releasing factor-41 neurons to alter dense-core vesicles could enhance or diminish the efficacy of the hypothalamohypophyseal communication underlying physiological adaptation to stress, as well as pathological changes.
Institute of Histology and Embryology, University of Geneva, Medical School, Switzerland.
L T
LT
Bertini
J Z
JZ
Kiss
D000315:Adrenalectomy; D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D003346:Corticotropin-Releasing Hormone / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D016253:Microscopy, Immunoelectron; D009474:Neurons / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000502:physiology*; D010904:Pituitary Gland, Posterior / Q000166:cytology* / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D014667:Vasopressins / Q000502:physiology
D018377:Neurotransmitter Agents; D014667:Vasopressins; D003346:Corticotropin-Releasing Hormone