RESUMEN
Testicular Leydig cells (LC) are modulated by several pathways, one of them being the histaminergic system. Heme oxygenase-1 (HO-1), whose upregulation comprises the primary response to oxidative noxae, has a central homeostatic role and might dysregulate LC functions when induced. In this report, we aimed to determine how hemin, an HO-1 inducer, affects LC proliferative capacity and whether HO-1 effects on LC functions are reversible. It was also evaluated if HO-1 interacts in any way with histamine, affecting its regulatory action over LC. MA-10 and R2C cell lines and immature rat LC were used as models. Firstly, we show that after a 24-h incubation with 25 µmol/L hemin, LC proliferation is reversibly impaired by cell cycle arrest in G2/M phase, with no evidence of apoptosis induction. Even though steroid production is abrogated after a 48-h exposure to 25 µmol/L hemin, steroidogenesis can be restored to control levels in a time-dependent manner if the inducer is removed from the medium. Regarding HO-1 and histamine interaction, it is shown that hemin abrogates histamine biphasic effect on steroidogenesis and proliferation. Working with histamine receptors agonists, we elucidated that HO-1 induction affects the regulation mediated by receptor types 1, 2 and 4. In summary, HO-1 induction arrests LC functions, inhibiting steroid production and cell cycle progression. Despite their reversibility, HO-1 actions might negatively influence critical phases of LC development and differentiation affecting their function as well as other androgen-dependent organs. What's more, we have described a hitherto unknown interaction between HO-1 induction and histamine effects.
Asunto(s)
Hemo-Oxigenasa 1/metabolismo , Histamina/farmacología , Células Intersticiales del Testículo/metabolismo , Animales , Apoptosis/efectos de los fármacos , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular , Proliferación Celular/efectos de los fármacos , Inducción Enzimática/efectos de los fármacos , Fase G2/efectos de los fármacos , Hemina/farmacología , Células Intersticiales del Testículo/citología , Células Intersticiales del Testículo/efectos de los fármacos , Masculino , Ratones , Mitosis/efectos de los fármacos , Ratas Sprague-Dawley , Esteroides/biosíntesisRESUMEN
The histamine H4 receptor (HRH4), discovered only 13 years ago, is considered a promising drug target for allergy, inflammation, autoimmune disorders and cancer, as reflected by a steadily growing number of scientific publications and patent applications. Although the presence of HRH4 has been evidenced in the testis, its specific localization or its role has not been established. Herein, we sought to identify the possible involvement of HRH4 in the regulation of Leydig cell function. We first evaluated its expression in MA-10 Leydig tumor cells and then assessed the effects of two HRH4 agonists on steroidogenesis and proliferation. We found that HRH4 is functionally expressed in MA-10 cells, and that its activation leads to the inhibition of LH/human chorionic gonadotropin-induced cAMP production and StAR protein expression. Furthermore, we observed decreased cell proliferation after a 24-h HRH4 agonist treatment. We then detected for the sites of HRH4 expression in the normal rat testis, and detected HRH4 immunostaining in the Leydig cells of rats aged 7-240 days, while 21-day-old rats also presented HRH4 expression in male gametes. Finally, we evaluated the effect of HRH4 activation on the proliferation of normal progenitor and immature rat Leydig cell culture, and both proved to be susceptible to the anti-proliferative effect of HRH4 agonists. Given the importance of histamine (2-(1H-imidazol-4-yl)ethanamine) in human (patho)physiology, continued efforts are directed at elucidating the emerging properties of HRH4 and its ligands. This study reveals new sites of HRH4 expression, and should be considered in the design of selective HRH4 agonists for therapeutic purposes.
Asunto(s)
Proliferación Celular , Células Intersticiales del Testículo/metabolismo , Progesterona/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores Histamínicos/metabolismo , Animales , Western Blotting , Bucladesina/farmacología , Línea Celular Tumoral , Células Cultivadas , Gonadotropina Coriónica/farmacología , AMP Cíclico/metabolismo , Relación Dosis-Respuesta a Droga , Guanidinas/farmacología , Agonistas de los Receptores Histamínicos/farmacología , Inmunohistoquímica , Indoles/farmacología , Células Intersticiales del Testículo/efectos de los fármacos , Masculino , Microscopía Confocal , Oximas/farmacología , Fosfoproteínas/metabolismo , Ratas Sprague-Dawley , Receptores Acoplados a Proteínas G/agonistas , Receptores Histamínicos H4 , Testículo/metabolismo , Tiourea/análogos & derivados , Tiourea/farmacologíaRESUMEN
Histamine (HA) is a neurotransmitter synthesized in most mammalian tissues exclusively by histidine decarboxylase enzyme. Among the plethora of actions mediated by HA, the modulatory effects on steroidogenesis and proliferation in Leydig cells (LCs) have been described recently. To determine whether the effects on LCs reported could be extrapolated to all steroidogenic systems, in this study, we assessed the effect of this amine on adrenal proliferation and steroidogenesis, using two adrenocortical cell lines as experimental models, murine Y1 cells and human NCI-H295R cells. Even when steroidogenesis was not modified by HA in adrenocortical cells, the biogenic amine inhibited the proliferation of H295R cells. This action was mediated by the activation of HRH1 subtype and an increase in the production of inositol phosphates as second messengers, causing cell-cycle arrest in the G2/M phase. These results indicate a new role for HA in the proliferation of human adrenocortical cells that could contribute to a better understanding of tumor pathology as well as to the development of new therapeutic agents.