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Leptin modulates norepinephrine-mediated melatonin synthesis in cultured rat pineal gland.

Peliciari-Garcia RA, Andrade-Silva J, Cipolla-Neto J, Carvalho CR - Biomed Res Int (2013)

Bottom Line: Pineal expression of Ob-Rb mRNA was also observed in vivo.Administration of leptin (1 nM) associated with NE ( 1 µM) reduced melatonin content as well as arylalkylamine-N-acetyl transferase (AANAT) activity and expression in cultured pineal glands.In conclusion, leptin inhibition of pineal melatonin synthesis appears to be mediated by a reduction in AANAT activity and expression as well as by increased expression of Icer mRNA.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil. rodrigousp@gmail.com

ABSTRACT
Pineal melatonin synthesis can be modulated by many peptides, including insulin. Because melatonin appears to alter leptin synthesis, in this work we aimed to investigate whether leptin would have a role on norepinephrine- (NE-)mediated melatonin synthesis in cultured rat pineal glands. According to our data, cultured rat pineal glands express leptin receptor isoform b (Ob-Rb). Pineal expression of Ob-Rb mRNA was also observed in vivo. Administration of leptin (1 nM) associated with NE ( 1 µM) reduced melatonin content as well as arylalkylamine-N-acetyl transferase (AANAT) activity and expression in cultured pineal glands. Leptin treatment per se induced the expression of STAT3 in cultured pineal glands, but STAT3 does not participate in the leptin modulation of NE-mediated pineal melatonin synthesis. In addition, the expression of inducible cAMP early repressor (ICER) was further induced by leptin challenge when associated with NE. In conclusion, leptin inhibition of pineal melatonin synthesis appears to be mediated by a reduction in AANAT activity and expression as well as by increased expression of Icer mRNA. Peptidergic signaling within the pineal gland appears to be one of the most important signals which modulates melatonin synthesis; leptin, as a member of this system, is not an exception.

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Leptin effect on Icer mRNA expression in cultured rat pineal gland. The glands were challenged with leptin (Lep 1 nM) associated with norepinephrine (NE 1 μM). One-way ANOVA, followed by Bonferroni's post hoc test. *P < 0.05 versus control, **P < 0.05 versus NE 1 μM. Data are reported as the number of transcripts per number of ribosomal protein L37a (Rpl37a) molecules. n = 6 glands/group and each experiment was repeated 3 times.
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fig6: Leptin effect on Icer mRNA expression in cultured rat pineal gland. The glands were challenged with leptin (Lep 1 nM) associated with norepinephrine (NE 1 μM). One-way ANOVA, followed by Bonferroni's post hoc test. *P < 0.05 versus control, **P < 0.05 versus NE 1 μM. Data are reported as the number of transcripts per number of ribosomal protein L37a (Rpl37a) molecules. n = 6 glands/group and each experiment was repeated 3 times.

Mentions: Finally, the expression of Icer, which directly inhibits the transcription of Aanat, was investigated in cultured pineal glands. Interestingly, the expression of Icer was further stimulated by leptin associated with NE than by NE alone (4.92 ± 0.49 versus 3.44 ± 0.24, P < 0.05, increase of 43%) (Figure 6).


Leptin modulates norepinephrine-mediated melatonin synthesis in cultured rat pineal gland.

Peliciari-Garcia RA, Andrade-Silva J, Cipolla-Neto J, Carvalho CR - Biomed Res Int (2013)

Leptin effect on Icer mRNA expression in cultured rat pineal gland. The glands were challenged with leptin (Lep 1 nM) associated with norepinephrine (NE 1 μM). One-way ANOVA, followed by Bonferroni's post hoc test. *P < 0.05 versus control, **P < 0.05 versus NE 1 μM. Data are reported as the number of transcripts per number of ribosomal protein L37a (Rpl37a) molecules. n = 6 glands/group and each experiment was repeated 3 times.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3713337&req=5

fig6: Leptin effect on Icer mRNA expression in cultured rat pineal gland. The glands were challenged with leptin (Lep 1 nM) associated with norepinephrine (NE 1 μM). One-way ANOVA, followed by Bonferroni's post hoc test. *P < 0.05 versus control, **P < 0.05 versus NE 1 μM. Data are reported as the number of transcripts per number of ribosomal protein L37a (Rpl37a) molecules. n = 6 glands/group and each experiment was repeated 3 times.
Mentions: Finally, the expression of Icer, which directly inhibits the transcription of Aanat, was investigated in cultured pineal glands. Interestingly, the expression of Icer was further stimulated by leptin associated with NE than by NE alone (4.92 ± 0.49 versus 3.44 ± 0.24, P < 0.05, increase of 43%) (Figure 6).

Bottom Line: Pineal expression of Ob-Rb mRNA was also observed in vivo.Administration of leptin (1 nM) associated with NE ( 1 µM) reduced melatonin content as well as arylalkylamine-N-acetyl transferase (AANAT) activity and expression in cultured pineal glands.In conclusion, leptin inhibition of pineal melatonin synthesis appears to be mediated by a reduction in AANAT activity and expression as well as by increased expression of Icer mRNA.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil. rodrigousp@gmail.com

ABSTRACT
Pineal melatonin synthesis can be modulated by many peptides, including insulin. Because melatonin appears to alter leptin synthesis, in this work we aimed to investigate whether leptin would have a role on norepinephrine- (NE-)mediated melatonin synthesis in cultured rat pineal glands. According to our data, cultured rat pineal glands express leptin receptor isoform b (Ob-Rb). Pineal expression of Ob-Rb mRNA was also observed in vivo. Administration of leptin (1 nM) associated with NE ( 1 µM) reduced melatonin content as well as arylalkylamine-N-acetyl transferase (AANAT) activity and expression in cultured pineal glands. Leptin treatment per se induced the expression of STAT3 in cultured pineal glands, but STAT3 does not participate in the leptin modulation of NE-mediated pineal melatonin synthesis. In addition, the expression of inducible cAMP early repressor (ICER) was further induced by leptin challenge when associated with NE. In conclusion, leptin inhibition of pineal melatonin synthesis appears to be mediated by a reduction in AANAT activity and expression as well as by increased expression of Icer mRNA. Peptidergic signaling within the pineal gland appears to be one of the most important signals which modulates melatonin synthesis; leptin, as a member of this system, is not an exception.

Show MeSH