Intracellular cAMP and Calcium Signaling by Serotonin in Mouse Cumulus-Oocyte Complexes

Abstract

cAMP and intracellular Ca 2ϩ are important second messengers involved in mammalian follicular growth and oocyte meiotic maturation. We investigated the capacity of the neurohormone serotonin (5-hydroxytryptamine, 5-HT) to regulate intracellular cAMP and Ca 2ϩ in mouse oocytes and surrounding cumulus cells. On the basis of a reverse transcription-polymerase chain reaction study, 5-HT 7 receptor mRNA is expressed in cumulus cells, oocytes, and embryos up to the four-cell stage, and 5-HT 2A and 5-HT 2B receptor mRNAs are expressed in cumulus cells only, whereas 5-HT 2C , 5-HT 4 , and 5-HT 6 receptors are expressed in neither oocytes nor cumulus cells. The addition of 5-HT (10 nM to 10 M) to isolated metaphase II oocytes had no effect on their internal cAMP or Ca 2ϩ levels, whereas it caused dose-dependent cAMP and Ca 2ϩ increases in cumulus cells. This cAMP increase in cumulus cells could be mimicked by 5-HT agonists with the following order of potency: 5-HT Ͼ 8-hydroxy-2-(di-n-propylamino) tetralin ϭ ␣-methyl-5-HT ϭ 5-carboxamidotryptamine maleate Ͼ 2-[1-(4-piperonyl)piperazinyl]benzo-triazole, thereby supporting a preferential involvement of 5-HT 7 receptors. As measured with cumulus cells preloaded with fura-2/acetoxymethyl ester (AM), the addition of 5-HT also caused dose-dependent Ca 2ϩ increases, which were probably linked to detected 5-HT 2A and 5-HT 2B receptors.

Physiological Endpoints for Potential SSRI Interactions in Fish

“…The same authors demonstrated that 5-HT caused a dose-dependent increase of cAMP and Ca 2+ levels in cumulus cells, presumably via 5-HT 7 and 5-HT 2A /5-HT 2B receptors, respectively. 146 Furthermore, 5-HT was shown to modulate gonadotropininduced steroid secretion of human granulosa cells in vitro. 147 In fish, the functional relationship of hypothalamus and pituitary regions varies between different species, but in general, the formation of neurological interfaces during phylogeny resulted in increased hypothalamic control of pituitary function.…”

Serotonin receptor 5-HT7 regulates morphology and migratory properties of dendritic cells

“…Next, we studied the effect of receptor stimulation on BMDC maturation. Immature and mature BMDCs were treated with the 5-HT 7 R agonist 5-carboxamidotryptamine maleate (5-CT; 10 µM) either alone or in combination with 10 µM of the highly selective 5-HT 7 R antagonist SB 269970 for 48 h. These concentrations were selected based on previously published data (Amireault and Dube, 2005;Crider et al, 2003;Kvachnina et al, 2005;Saitow et al, 2009). Quantitative analysis of flow cytometry data showed no difference in the number of immature and mature BMDCs after 5-HT 7 R stimulation (Fig.…”

Local serotonergic signaling in mammalian follicles, oocytes and early embryos

“…Also using RT-PCR, it was found that mouse oocytes and pre-implantation embryos, up to the blastocyst stage, expressed 5-HT 1D but not 5-HT 1B or 5-HT 2C receptors (Vesela et al, 2003). Through both RT-PCR and immunological analyses, additional receptors, namely 5-HT 2A and 5-HT 2B , were discovered in mouse cumulus cells while 5-HT 7 receptor was expressed in both cumulus cells and oocytes as well as in embryos up to the four-cell stage, whereas 5-HT 2C , 5-HT 4 and 5-HT 6 receptors were not detected in any of these cells (Amireault and Dubé, 2005b). In contrast to mice, hamster oocytes appear to express the 5-HT 2A receptor but not the 5-HT 7 subtype (Amireault and Dubé, 2005b).…”

“…Through both RT-PCR and immunological analyses, additional receptors, namely 5-HT 2A and 5-HT 2B , were discovered in mouse cumulus cells while 5-HT 7 receptor was expressed in both cumulus cells and oocytes as well as in embryos up to the four-cell stage, whereas 5-HT 2C , 5-HT 4 and 5-HT 6 receptors were not detected in any of these cells (Amireault and Dubé, 2005b). In contrast to mice, hamster oocytes appear to express the 5-HT 2A receptor but not the 5-HT 7 subtype (Amireault and Dubé, 2005b). As part of a study on expressed sequence tags amplified by PCR, human oocytes also appeared to express 5-HT 2A receptors (Neilson et al, 2000), even though more direct confirmation would be required, as well as for the reported possible expression of 5-HT 5A receptor in mouse oocytes detected by microarray analyses of RNA (Hinckley et al, 2005).…”