title: Pituitary growth hormone network responses are sexually dimorphic and regulated by gonadal steroids in adulthood.
abstract: There are well-recognized sex differences in many pituitary endocrine axes, usually thought to be generated by gonadal steroid imprinting of the neuroendocrine hypothalamus. However, the recognition that growth hormone (GH) cells are arranged in functionally organized networks raises the possibility that the responses of the network are different in males and females. We studied this by directly monitoring the calcium responses to an identical GH-releasing hormone (GHRH) stimulus in populations of individual GH cells in slices taken from male and female murine GH-eGFP pituitary glands. We found that the GH cell network responses are sexually dimorphic, with a higher proportion of responding cells in males than in females, correlated with greater GH release from male slices. Repetitive waves of calcium spiking activity were triggered by GHRH in some males, but were never observed in females. This was not due to a permanent difference in the network architecture between male and female mice; rather, the sex difference in the proportions of GH cells responding to GHRH were switched by postpubertal gonadectomy and reversed with hormone replacements, suggesting that the network responses are dynamically regulated in adulthood by gonadal steroids. Thus, the pituitary gland contributes to the sexually dimorphic patterns of GH secretion that play an important role in differences in growth and metabolism between the sexes.
authors.affiliation: Department of Endocrinology, Institute of Functional Genomics, 34094 Montpellier, France.
authors.forename: Claudia
authors.initials: C
authors.lastname: Sanchez-Cardenas
authors.forename: Pierre
authors.initials: P
authors.lastname: Fontanaud
authors.forename: Zhenhe
authors.initials: Z
authors.lastname: He
authors.forename: Chrystel
authors.initials: C
authors.lastname: Lafont
authors.forename: Anne-Cécile
authors.initials: AC
authors.lastname: Meunier
authors.forename: Marie
authors.initials: M
authors.lastname: Schaeffer
authors.forename: Danielle
authors.initials: D
authors.lastname: Carmignac
authors.forename: François
authors.initials: F
authors.lastname: Molino
authors.forename: Nathalie
authors.initials: N
authors.lastname: Coutry
authors.forename: Xavier
authors.initials: X
authors.lastname: Bonnefont
authors.forename: Laurie-Anne
authors.initials: LA
authors.lastname: Gouty-Colomer
authors.forename: Elodie
authors.initials: E
authors.lastname: Gavois
authors.forename: David J
authors.initials: DJ
authors.lastname: Hodson
authors.forename: Paul
authors.initials: P
authors.lastname: Le Tissier
authors.forename: Iain C A F
authors.initials: IC
authors.lastname: Robinson
authors.forename: Patrice
authors.initials: P
authors.lastname: Mollard
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D005260:Female; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D012727:Sex Characteristics
chemical_list: D012739:Gonadal Steroid Hormones; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D002118:Calcium