title: Partial characterization of a thyrotropin releasing hormone-sensitive glycosyl-phosphatidylinositol in pituitary lactotrophes.
abstract: Metabolic labelling experiments performed with cultured pituitary lactotrophes revealed the presence of a glycosyl-phosphatidylinositol (GPtdIns) structurally related to GPtdIns lipids isolated from other cell types as demonstrated by: (i) metabolic incorporation of [3H]galactose, [3H]glucosamine and [3H]inositol into the polar inositolphosphoglycan moiety (InsPG) and [3H]myristate and [3H]palmitate into the diacylglycerol (DAG) backbone of GPtdIns; (ii) sensitivity of the [3H]labelled GPtdIns to nitrous acid deamination and; (iii) sensitivity of GPtdIns to phosphatidylinositol (PtdIns)-specific phospholipase C (PLC) hydrolysis. In cultured pituitary cells labelled to isotopic steady state with 10 microCi/ml of [3H]glucosamine, treatment with hypothalamic TRH (10(-6) M) induced a rapid and transient hydrolysis (ca. 50%) of the labelled GPtdIns. Moreover, as demonstrated in [3H]inositol labelled cells, treatment with thyrotropin releasing hormone (TRH) elicited the cleavage of [3H]GPtdIns in a similar manner, and this effect was followed by the phosphoinositide (PtdIns, PtdInsP and PtdInsP2) hydrolysis 30 s later. These results suggest that the phosphodiesterase cleavage of GPtdIns could be an early event implicated in TRH action in pituitary lactotrophes.
authors.affiliation: Departamento de Endocrinología Celular y Molecular, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Benítez
authors.forename: L F
authors.initials: LF
authors.lastname: Fanjul
authors.forename: C M
authors.initials: CM
authors.lastname: Ruiz de Galarreta
authors.forename: J
authors.initials: J
authors.lastname: Quintana Aguiar
authors.forename: J
authors.initials: J
authors.lastname: González Reyes
authors.forename: I
authors.initials: I
authors.lastname: Hernández
authors.forename: P
authors.initials: P
authors.lastname: Santana Delgado
authors.forename: J
authors.initials: J
authors.lastname: Cabrera Oliva
authors.forename: R
authors.initials: R
authors.lastname: Alonso Solís
authors.forename: F
authors.initials: F
authors.lastname: Estévez Rosas
mesh_terms: D000818:Animals; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D017261:Glycosylphosphatidylinositols / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000737:chemistry* / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D005227:Fatty Acids; D017261:Glycosylphosphatidylinositols; D013973:Thyrotropin-Releasing Hormone