title: Paliperidone and aripiprazole differentially affect the strength of calcium-secretion coupling in female pituitary lactotrophs.
abstract: Hyperprolactinemia is a common adverse in vivo effect of antipsychotic medications that are used in the treatment of patients with schizophrenia. Here, we compared the effects of two atypical antipsychotics, paliperidone and aripiprazole, on cAMP/calcium signaling and prolactin release in female rat pituitary lactotrophs in vitro. Dopamine inhibited spontaneous cAMP/calcium signaling and prolactin release. In the presence of dopamine, paliperidone rescued cAMP/calcium signaling and prolactin release in a concentration-dependent manner, whereas aripiprazole was only partially effective. In the absence of dopamine, paliperidone stimulated cAMP/calcium signaling and prolactin release, whereas aripiprazole inhibited signaling and secretion more potently but less effectively than dopamine. Forskolin-stimulated cAMP production was facilitated by paliperidone and inhibited by aripiprazole, although the latter was not as effective as dopamine. None of the compounds affected prolactin transcript activity, intracellular prolactin accumulation, or growth hormone secretion. These data indicate that paliperidone has dual hyperprolactinemic actions in lactotrophs i) by preserving the coupling of spontaneous electrical activity and prolactin secretion in the presence of dopamine and ii) by inhibiting intrinsic dopamine receptor activity in the absence of dopamine, leading to enhanced calcium signaling and secretion. In contrast, aripiprazole acts on prolactin secretion by attenuating, but not abolishing, calcium-secretion coupling.
authors.affiliation: Section on Cellular Signaling, National Institutes of Child Health and Human Development, NIH, Bethesda, MD 20892.
authors.forename: Marek
authors.initials: M
authors.lastname: Kucka
authors.affiliation: Section on Cellular Signaling, National Institutes of Child Health and Human Development, NIH, Bethesda, MD 20892.
authors.forename: Melanija
authors.initials: M
authors.lastname: Tomić
authors.affiliation: Section on Cellular Signaling, National Institutes of Child Health and Human Development, NIH, Bethesda, MD 20892.
authors.forename: Ivana
authors.initials: I
authors.lastname: Bjelobaba
authors.affiliation: Section on Cellular Signaling, National Institutes of Child Health and Human Development, NIH, Bethesda, MD 20892.
authors.forename: Stanko S
authors.initials: SS
authors.lastname: Stojilkovic
authors.affiliation: Clinical Trials Unit, Kennedy Krieger Institute/Johns Hopkins School of Medicine, Baltimore, MD 21205.
authors.forename: Dejan B
authors.initials: DB
authors.lastname: Budimirovic
mesh_terms: D000818:Animals; D000068180:Aripiprazole / Q000009:adverse effects* / Q000627:therapeutic use; D020013:Calcium Signaling / Q000187:drug effects; D004298:Dopamine / Q000008:administration & dosage / Q000378:metabolism; D005260:Female; D006801:Humans; D006966:Hyperprolactinemia / Q000139:chemically induced; D052682:Lactotrophs / Q000187:drug effects / Q000378:metabolism; D000068882:Paliperidone Palmitate / Q000009:adverse effects* / Q000627:therapeutic use; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D012559:Schizophrenia / Q000150:complications* / Q000188:drug therapy; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000068180:Aripiprazole; D011388:Prolactin; D000068882:Paliperidone Palmitate; D004298:Dopamine