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.
Bertini
L T
LT
Institute of Histology and Embryology, University of Geneva, Medical School, Switzerland.
Kiss
J Z
JZ
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