AI Article Synopsis
- The study investigated how alpha and beta-receptor activation affects cAMP levels in pinealocytes from female rats, specifically comparing ovariectomized rats to intact rats during proestrus.
- Isoproterenol significantly boosted cAMP levels in both groups, with a stronger response observed in rats treated with RU486 or Tamoxifen alone, but not when both were used together.
- The combination of isoproterenol and phenylephrine had a synergistic effect in ovariectomized rats and those treated with RU486, indicating that ovarian steroids may influence how these receptors interact and modify melatonin synthesis throughout the oestrous cycle.
Article Abstract
We have examined the effects of alpha 1- and beta-receptor activation on cyclic AMP (cAMP) accumulation in cultured pinealocytes from female ovariectomized rats, and from intact rats at proestrus treated with the antiestrogen Tamoxifen, the antiprogestagen RU486, or with both. Isoproterenol (a beta-agonist) significantly increased cAMP levels in pinealocytes from intact and ovariectomized rats. This response was considerably enhanced in pinealocytes from rats treated with RU486 or Tamoxifen alone, but not with both. Moreover, incubation of pinealocytes with isoproterenol together with phenylephrine (an alpha 1-agonist) produced a synergistic effect in animals that had been ovariectomized, or that had received RU486, either alone or in combination with Tamoxifen. These results suggest that, in female rats, ovarian steroids may regulate the interactions between alpha 1- and beta-adrenergic receptors, and thus modulate pineal melatonin synthesis during the oestrous cycle through these mechanisms.
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| http://dx.doi.org/10.1097/00001756-199501000-00030 | DOI Listing |
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