Regulation of glycogen content in rat pineal gland by norepinephrine

Eliseo Eugenin, Claudia G. Sáez, Gladys Garcés, Juan C. Sáez

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

In the rat pineal gland the glycogen stores were cytochemically localized in astrocytes and pinealocytes. Moreover, it was found that norepinephrine (NE) induced a time- and concentration-dependent reduction in pineal glycogen content and yielded lactic acid. The NE effect was prevented by blocking α1- but not α2 or β-adrenoceptors. Activation of α2- adrenoceptors induced a small decrease in glycogen levels that could have pre- and postsynaptic components. Activation of β-adrenoceptors with 10- 12-10-3 M isoproterenol (ISO) induced a bell shape concentration- response curve, presumably due to desensitization, since the response induced by 10-4 M ISO was greater with shorter period of stimulation. On the other hand, activation of α1-adrenoceptors with 10-12-10-3 M phenylephrine (PHN) induced a hyperbolic concentration-response curve with a maximum at concentrations above 10-8 M. Moreover, treatment with ISO drastically reduced the response induced by PHN concentrations lower but not higher than 10-6 M, favoring a concentration-dependent response between 10-6 and 10- 4 M PHN, similar to that induced by equimolar NE concentrations. Thus, the NE-induced reduction in glycogen content of the rat pineal gland is mainly mediated by α-adrenoceptors and modulated by intracellular mechanisms by β- adrenoceptors.

Original languageEnglish (US)
Pages (from-to)34-41
Number of pages8
JournalBrain Research
Volume760
Issue number1-2
DOIs
StatePublished - Jun 20 1997
Externally publishedYes

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Keywords

  • Adrenoceptor
  • Desensitization
  • Epiphysis cerebri
  • Glycogen
  • Lactic acid
  • Norepinephrine

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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