RT info:eu-repo/semantics/article
T1 Multi-responsiveness of single anterior pituitary cells to hypothalamic-releasing hormones: A cellular basis for paradoxical secretion
A1 Villalobos Jorge, Carlos
A1 Núñez Llorente, Lucía
A1 Frawley, L. Stephen
A1 García-Sancho Martín, Francisco Javier
A1 Sánchez, Ana
K1 Calcium
K1 Calcio
K1 Growth hormone
K1 Hormona del crecimiento
K1 Prolactin
K1 Prolactina
AB The classic view for hypothalamic regulation of anterior pituitary (AP) hormone secretion holds that release of each AP hormone is controlled specifically by a corresponding hypothalamic-releasing hormone (HRH). In this scenario, binding of a given HRH (thyrotropin-, growth hormone-, corticotropin-, and luteinizing hormone-releasing hormones) to specific receptors in its target cell increases the concentration of cytosolic Ca2+ ([Ca2+]i), thereby selectively stimulating the release of the appropriate hormone. However, “paradoxical” responses of AP cells to the four well-established HRHs have been observed repeatedly with both in vivo and in vitro systems, raising the possibility of functional overlap between the different AP cell types. To explore this possibility, we evaluated the effects of HRHs on [Ca2+]i in single AP cells identified immunocytochemically by the hormone they stored. We found that each of the five major AP cell types contained discrete subpopulations that were able to respond to several HRHs. The relative abundance of these multi-responsive cells was 59% for lactotropes, 33% for thyrotropes, and in the range of 47–55% for gonadotropes, corticotropes, and somatotropes. Analysis of prolactin release from single living cells revealed that each of the four HRHs tested were able to induce hormone release from a discrete lactotrope subpopulation, the size of which corresponded closely to that in which [Ca2+]i changes were induced by the same secretagogues. When viewed as a whole, our diverse functional measurements of multi-responsiveness suggest that hypothalamic control of pituitary function is more complicated than previously envisioned. Moreover, they provide a cellular basis for the so-called “paradoxical” behavior of pituitary cells to hypothalamic hypophysiotropic agents.
PB National Academy of Sciences
SN 1091-6490
YR 1997
FD 1997
LK http://uvadoc.uva.es/handle/10324/45077
UL http://uvadoc.uva.es/handle/10324/45077
LA eng
NO Proceedings of the National Academy of Sciences of the United States of America, 1997, vol. 94, n. 25. p. 14132-14137
NO Producción Científica
DS UVaDOC
RD 24-nov-2024