A specific adenylyl cyclase inhibitor (DDA) and a cyclic AMP-dependent protein kinase inhibitor (H-89) block the action of equine growth hormone on in vitro maturation of equine oocytes

Bi-directional modulation of hyperpolarization-activated cation currents (Ih) by ethanol in rat hippocampal CA3 pyramidal neurons

It is widely acknowledged that ethanol (EtOH) can alter many neuronal functions, including synaptic signaling, firing discharge, and membrane excitability, through its interaction with multiple membrane proteins and intracellular pathways. Previous work has demonstrated that EtOH enhances the firing rate of hippocampal GABAergic interneurons and thus the presynaptic GABA release at CA1 and CA3 inhibitory synapses through a positive modulation of the hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels. Activation of HCN channels produce an inward current, commonly called I_h, which plays an essential role in generating/regulating specific neuronal activities in GABAergic interneurons and principal glutamatergic pyramidal neurons such as those in the CA3 subregion. Since the direct effect of EtOH on HCN channels expressed in CA3 pyramidal neurons was not thoroughly elucidated, we investigated the possible interaction between EtOH and HCN channels and the impact on excitability and postsynaptic integration of these neurons. Patch-clamp recordings were performed in single CA3 pyramidal neurons from acute male rat coronal hippocampal slices. Our results show that EtOH modulates HCN-mediated I_h in a concentration-dependent and bi-directional manner, with a positive modulation at lower (20 mM) and an inhibitory action at higher (60-80 mM) concentrations. The modulation of I_h by EtOH was mimicked by forskolin, antagonized by different drugs that selectively interfere with the AC/cAMP/PKA intracellular pathway, as well as by the selective HCN inhibitor ZD7288. Altogether, these data further support the evidence that HCN channels may represent an important molecular target through which EtOH may regulate neuronal activity.

ATP is stored in lysosomes of greater epithelial ridge supporting cells in newborn rat cochleae

Adenosine triphosphate (ATP), which plays a crucial role in both developing and mature cochleae, is released from greater epithelial ridge (GER) supporting cells of the rat cochlea, but the organelles in which ATP is stored have not yet been identified. Thus, we studied the organelles involved in ATP storage and suggest that lysosomes provide this function. GER supporting cells of newborn rats were isolated, purified, and cultured, and labeled vesicles within the supporting cells were identified via confocal microscopy and transmission electron microscopy (TEM). ATP release from GER supporting cells after glycyl-L-phenylalanine-β-naphthylamide (GPN) treatment was measured. The specifically labeled organelles observed by confocal microscopy and TEM were lysosomes, and GPN treatment enhanced ATP luminescence in the extracellular fluid of the supporting cells. The release of ATP from supporting cells was affected by changes in intra- and extracellular Ca²⁺ concentrations. In addition, changes in the intracellular Ca²⁺ caused by inhibiting the phospholipase signaling pathway affected the release of ATP from supporting cells. We demonstrated that ATP is stored in the lysosomes of GER supporting cells within newborn rat cochleae and that ATP release from GER supporting cells may be Ca²⁺ -dependent.

Growth Hormone Promotes in vitro Maturation of Human Oocytes

Increasing the success rate of in vitro maturation (IVM) for human oocytes has a major clinical significance. Previous studies have shown that growth hormone (GH) added into IVM medium could promote IVM of oocytes from non-human beings. However, few studies on systematic IVM for human oocytes with GH have been reported. Human germinal vesicle (GV) oocytes collected for IVM were cultured with different concentrations of GH to optimize the concentration. Metaphase II (MII) stage oocytes obtained from IVM were fertilized by intracytoplasmic sperm injection (ICSI). Maturation rate, fertilization rate, and blastocyst rate were assessed after IVM with or without GH. Furthermore, gene expression profiles were compared in oocytes between the two groups using single-cell RNA-seq. The optimal concentration of GH for IVM was 200 ng/ml, and the maturation rate of this group reached 70% which was double that of the control group (35%, P = 0.004). The fertilization rate (73.1 vs. 60.3%) and blastocyst rate (25.0 vs. 15.5%) both had an increasing trend in the GH group compared to controls. Single-cell RNA-Seq and real-time PCR data showed that GH could significantly enhance the expression of genes associated with meiotic progression and embryo development, such as AURKA (aurora kinase A, P = 0.007), PDIA6 (protein disulfide isomerase family A member 6, P = 0.007), LINGO2 (leucine rich repeat and Ig domain containing 2, P = 0.007), and CENPJ (centromere protein J, P = 0.039). Taken together, GH could promote maturation of human oocytes, probably through accelerating meiotic progression, balancing redox homeostasis of cellular environment, and promoting oocyte developmental competence.

Growth hormone and reproduction: a review of endocrine and autocrine/paracrine interactions

The somatotropic axis, consisting of growth hormone (GH), hepatic insulin-like growth factor I (IGF-I), and assorted releasing factors, regulates growth and body composition. Axiomatically, since optimal body composition enhances reproductive function, general somatic actions of GH modulate reproductive function. A growing body of evidence supports the hypothesis that GH also modulates reproduction directly, exerting both gonadotropin-dependent and gonadotropin-independent actions in both males and females. Moreover, recent studies indicate GH produced within reproductive tissues differs from pituitary GH in terms of secretion and action. Accordingly, GH is increasingly used as a fertility adjunct in males and females, both humans and nonhumans. This review reconsiders reproductive actions of GH in vertebrates in respect to these new conceptual developments.