GnRH Neuron-Specific Ablation of Gαq/11 Results in Only Partial Inactivation of the Neuroendocrine-Reproductive Axis in Both Male and Female Mice: In Vivo Evidence for Kiss1r-Coupled Gαq/11-Independent GnRH Secretion.

The gonadotropin-releasing hormone (GnRH) is the master regulator of fertility and kisspeptin (KP) is a potent trigger of GnRH secretion from GnRH neurons. KP signals via KISS1R, a Gαq/11-coupled receptor, and mice bearing a global deletion of Kiss1r (Kiss1r(-/-)) or a GnRH neuron-specific deletion of Kiss1r (Kiss1r(d/d)) display hypogonadotropic hypogonadism and infertility. KISS1R also signals via ß-arrestin, and in mice lacking ß-arrestin-1 or -2, KP-triggered GnRH secretion is significantly diminished. Based on these findings, we hypothesized that ablation of Gαq/11 in GnRH neurons would diminish but not completely block KP-triggered GnRH secretion and that Gαq/11-independent GnRH secretion would be sufficient to maintain fertility. To test this, Gnaq (encodes Gαq) was selectively inactivated in the GnRH neurons of global Gna11 (encodes Gα11)-null mice by crossing Gnrh-Cre and Gnaq(fl/fl);Gna11(-/-) mice. Experimental Gnaq(fl/fl);Gna11(-/-);Gnrh-Cre (Gnaq(d/d)) and control Gnaq(fl/fl);Gna11(-/-) (Gnaq(fl/fl)) littermate mice were generated and subjected to reproductive profiling. This process revealed that testicular development and spermatogenesis, preputial separation, and anogenital distance in males and day of vaginal opening and of first estrus in females were significantly less affected in Gnaq(d/d) mice than in previously characterized Kiss1r(-/-) or Kiss1r(d/d) mice. Additionally, Gnaq(d/d) males were subfertile, and although Gnaq(d/d) females did not ovulate spontaneously, they responded efficiently to a single dose of gonadotropins. Finally, KP stimulation triggered a significant increase in gonadotropins and testosterone levels in Gnaq(d/d) mice. We therefore conclude that the milder reproductive phenotypes and maintained responsiveness to KP and gonadotropins reflect Gαq/11-independent GnRH secretion and activation of the neuroendocrine-reproductive axis in Gnaq(d/d) mice. SIGNIFICANCE STATEMENT: The gonadotropin-releasing hormone (GnRH) is the master regulator of fertility. Over the last decade, several studies have established that the KISS1 receptor, KISS1R, is a potent trigger of GnRH secretion and inactivation of KISS1R on the GnRH neuron results in infertility. While KISS1R is best understood as a Gαq/11-coupled receptor, we previously demonstrated that it could couple to and signal via non-Gαq/11-coupled pathways. The present study confirms these findings and, more importantly, while it establishes Gαq/11-coupled signaling as a major conduit of GnRH secretion, it also uncovers a significant role for non-Gαq/11-coupled signaling in potentiating reproductive development and function. This study further suggests that by augmenting signaling via these pathways, GnRH secretion can be enhanced to treat some forms of infertility.

Clinical efficacy of macrophage-activating Chinese mixed herbs (MACH) in improvement of embryo qualities in women with long-term infertility of unknown etiology.

Despite the recent technological advances in in vitro fertilization and embryo transfer (IVF-ET), a significant proportion of women still do not become pregnant after long-term infertility, whether it is originally due to older age or other undetermined factors. In the present study, macrophage activating Chinese herbs (MACH) were evaluated for their effects on embryo qualities in women who were undergoing repeated IVF-ET because of long-term infertility. Thirty women, who had significantly low rates of developing good quality cleaved embryos and did not become pregnant after three or more cycles of Assisted Reproductive Technology (ART) procedure, were included in the study. Oral administration of MACH significantly increased the percentage of good quality early stage blastocysts (the number of grade 1 or grade 2 cleaved embryos/the number of retrieved oocytes) from 18.7 ± 16.2% to 36.1 ± 27.1% (1.9-fold increase, p < 0.01). The rate of good quality early stage blastocysts increased in all patients. In 19 patients who desired embryo transfer using late stage blastocysts, MACH significantly increased the percentage of late stage blastocysts from the initial value of 14.8 ± 11.2% to 21.1 ± 23.1% (1.4-fold increase, p < 0.05). The rate of embryonic progress into late stage blastocyst increased in 52.6% (10/19) of the patients. Furthermore, treatment with MACH significantly decreased the plasma follicle stimulating hormone (FSH) concentration on the day of oocyte retrieval from 14.4 ± 3.2 to 10.5 ± 2.4 mIU/ml (p < 0.05). No adverse events were observed with MACH supplementation, and there was no patient dropout. Administration of MACH resulted in improved embryo quality in the difficult cases. The present study demonstrates a new benefit of this herbal blend in women with refractory infertility of unknown etiology.

Novel concepts about normal sexual differentiation of reproductive neuroendocrine function and the developmental origins of female reproductive dysfunction: the sheep model.

The neuroendocrine regulation of GnRH secretion plays a central role in timing gamete release in both sexes. This regulation is more complex in the female because the discontinuous release of ova is more complex than the continuous release of spermatozoa. This review provides an evolving understanding of the sex differences in reproductive neuroendocrine controls and how these differences arise. The rules for sexual differentiation of steroid feedback control of GnRH secretion conceptually parallel the well-established principles that underlie the sexual differentiation of the internal and external genitalia. In the context of the neuroendocrine regulation of the ovarian cycle, and using the sheep as a model, four steroid feedback controls for GnRH secretion are inherent (default). They require no ovarian developmental input to function appropriately during adulthood. Two steroid feedback controls regulate the preovulatory surge mode of GnRH secretion, and two regulate the pulsatile mode. If the individual is a male, three steroid feedback controls of GnRH secretion become unnecessary or irrelevant, and these are abolished or become functionally inoperative through programmed reductions in hypothalamic sensitivity. This central programming occurs through exposure of presynaptic GnRH neurons in the developing male brain to the androgenic and estrogenic actions of testicular steroids. In precocial species such as ruminants, this programming begins well before birth. Understanding how GnRH secretion normally becomes sexually differentiated is of practical importance to determining how inappropriate hormonal environments during development can variously malprogram the neuroendocrine system to produce a variety of reproductive dysfunctions relating to patterning of gonadotropin secretion.