Insulin temporal sensitivity and its signaling pathway in the rat pineal gland

Author(s)

Peliciari-Garcia, Rodrigo A. ^[1] ; Marcal, Anderson C. ^[1] ; Silva, Jessica A. ^[1] ; Carmo-Buonfiglio, Daniella ^[1] ; Amaral, Fernanda G. ^[1] ; Afeche, Solange Castro ^[2] ; Cipolla-Neto, Jose ^[1] ; Carvalho, Carla R. O. ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Physiol & Biophys, Inst Biomed Sci 1, Sao Paulo - Brazil

^[2] Butantan Inst, Pharmacol Lab, Sao Paulo - Brazil

• Document type: Journal article
• Source: Life Sciences; v. 87, n. 5-6, p. 169-174, JUL 31 2010.
• Web of Science Citations: 14

Abstract

Aims: In our previous work, we reported that the insulin potentiating effect on melatonin synthesis is regulated by a post-transcriptional mechanism. However, the major proteins of the insulin signaling pathway (ISP) and the possible pathway component recruited on the potentiating effect of insulin had not been characterized. A second question raised was whether windows of sensitivity to insulin exist in the pineal gland due to insulin rhythmic secretion pattern. Main methods: Melatonin content from norepinephrine(NE)-synchronized pineal gland cultures was quantified by high performance liquid chromatography with electrochemical detection and arylalkylamine-N-acetyltransferase (AANAT) activity was assayed by radiometry. Immunoblotting and immunoprecipitation techniques were performed to establish the ISP proteins expression and the formation of 14-3-3: AANAT complex, respectively. Key findings: The temporal insulin susceptibility protocol revealed two periods of insulin potentiating effect, one at the beginning and another one at the end of the in vitro induced ``night{''}. In some Timed-insulin Stimulation (TSs), insulin also promoted a reduction on melatonin synthesis, showing its dual action in cultured pineal glands. The major ISP components, such as IR beta, IGF-1R, IRS-1, IRS-2 and PI3K(p85), as well tyrosine phosphorylation of pp85 were characterized within pineal glands. Insulin is not involved in the 14-3-3:AANAT complex formation. The blockage of PI3K by LY 294002 reduced melatonin synthesis and AANAT activity. Significance: The present study demonstrated windows of differential insulin sensitivity, a functional ISP and the PI3K-dependent insulin potentiating effect on NE-mediated melatonin synthesis, supporting the hypothesis of a crosstalk between noradrenergic and insulin pathways in the rat pineal gland. (C) 2010 Elsevier Inc. All rights reserved. (AU)

• FAPESP's process: 07/07790-6 - Role of insulin on the regulation of melatonin synthesis by pineal gland: action mechanisms and functional characteristics
• Grantee: Rodrigo Antonio Peliciari Garcia
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 04/06767-2 - Melatonin and the control of energy metabolism: central and peripheral actions and their interaction with other hormones
• Grantee: José Cipolla Neto
• Support type: Research Projects - Thematic Grants