BACKGROUND. Sex, emotion, and reproduction are fundamental and tightly entwined aspects of human behavior. At a population level in humans, both the desire for sexual stimulation and the desire to bond with a partner are important precursors to reproduction. However, the relationships between these processes are incompletely understood. The limbic brain system has key roles in sexual and emotional behaviors, and is a likely candidate system for the integration of behavior with the hormonal reproductive axis. We investigated the effects of kisspeptin, a recently identified key reproductive hormone, on limbic brain activity and behavior.METHODS. Using a combination of functional neuroimaging and hormonal and psychometric analyses, we compared the effects of kisspeptin versus vehicle administration in 29 healthy heterosexual young men.RESULTS. We demonstrated that kisspeptin administration enhanced limbic brain activity specifically in response to sexual and couple-bonding stimuli. Furthermore, kisspeptin’s enhancement of limbic brain structures correlated with psychometric measures of reward, drive, mood, and sexual aversion, providing functional significance. In addition, kisspeptin administration attenuated negative mood.CONCLUSIONS. Collectively, our data provide evidence of an undescribed role for kisspeptin in integrating sexual and emotional brain processing with reproduction in humans. These results have important implications for our understanding of reproductive biology and are highly relevant to the current pharmacological development of kisspeptin as a potential therapeutic agent for patients with common disorders of reproductive function.FUNDING. National Institute for Health Research (NIHR), Wellcome Trust (Ref 080268), and the Medical Research Council (MRC).

Prenatal folic acid (FA) supplementation prevents neural tube defects. Folate receptor alpha (FRa) is critical for embryonic development, including neural crest (NC) development. Previously we showed that FRa translocates to the nucleus in response to FA, where it acts as a transcription factor. In this study, we examined if FA through interaction with FRa regulates stem cell characteristics of cranial neural crest cells (CNCCs)-critical for normal development. We hypothesized that FRa upregulates coding genes and simultaneously downregulates non-coding miRNA which targets coding genes in CNCCs. Quantitative RT-PCR and chromatin immunoprecipitation showed that FRa upregulates Oct4, Sox2, and Klf4 by binding to their cis-regulator elements-5 0 enhancer/promoters defined by H3K27Ac and p300 occupancy. FA via FRa downregulates miRNAs, miR-138 and miR-let-7, which target Oct4 and Trim71 (an Oct4 downstream effector), respectively. Co-immunoprecipitation data suggests that FRa interacts with the Drosha-DGCR8 complex to affect pre-miRNA processing. Transfecting anti-miR-138 or anti-miR-let-7 into nonproliferating neural crest cells (NCCs) derived from Splotch (Sp 2/2 ), restored their proliferation potential. In summary, these results suggest a novel pleiotropic role of FRa: (a) direct activation of Oct4, Sox2, and Klf4 genes; and (b) repression of biogenesis of miRNAs that target these genes or their effector molecules.

BACKGROUND. Resting brain connectivity is a crucial component of human behavior demonstrated by disruptions in psychosexual and emotional disorders. Kisspeptin, a recently identified critical reproductive hormone, can alter activity in certain brain structures but its effects on resting brain connectivity and networks in humans remain elusive.METHODS. We determined the effects of kisspeptin on resting brain connectivity (using functional neuroimaging) and behavior (using psychometric analyses) in healthy men, in a randomized double-blinded 2-way placebo-controlled study.RESULTS. Kisspeptin’s modulation of the default mode network (DMN) correlated with increased limbic activity in response to sexual stimuli (globus pallidus r = 0.500, P = 0.005; cingulate r = 0.475, P = 0.009). Furthermore, kisspeptin’s DMN modulation was greater in men with less reward drive (r = –0.489, P = 0.008) and predicted reduced sexual aversion (r = –0.499, P = 0.006), providing key functional significance. Kisspeptin also enhanced key mood connections including between the amygdala-cingulate, hippocampus-cingulate, and hippocampus–globus pallidus (all P < 0.05). Consistent with this, kisspeptin’s enhancement of hippocampus–globus pallidus connectivity predicted increased responses to negative stimuli in limbic structures (including the thalamus and cingulate [all P < 0.01]).CONCLUSION. Taken together, our data demonstrate a previously unknown role for kisspeptin in the modulation of functional brain connectivity and networks, integrating these with reproductive hormones and behaviors. Our findings that kisspeptin modulates resting brain connectivity to enhance sexual and emotional processing and decrease sexual aversion, provide foundation for kisspeptin-based therapies for associated disorders of body and mind.FUNDING. NIHR, MRC, and Wellcome Trust.

Context:A subpopulation of hypothalamic neurons colocalize three neuropeptides, namely kisspeptin, neurokinin B (NKB), and dynorphin, collectively termed KNDy neurons. Animal studies suggest they interact to affect pulsatile GnRH release (KNDy hypothesis); kisspeptin stimulates, NKB modulates, and dynorphin (an opioid) inhibits.Objective:To investigate the KNDy hypothesis in humans, we assessed for the first time the effects of the coadministration of kisspeptin-54, NKB, and an opioid receptor antagonist, naltrexone, on LH pulsatility (surrogate marker for GnRH pulsatility) and gonadotropin release.Design, Setting, and Participants:This was an ethically approved prospective, single-blinded, placebo-controlled study. Healthy male volunteers (n = 5/group) attended our research facility for eight study visits.Intervention and Main Outcome Measure:After 1 hour of baseline blood sampling, participants received a different intervention at each visit: oral 50 mg naltrexone, 8-hour iv infusions of vehicle, 2.56 nmol/kg · h NKB, 0.1 nmol/kg · h kissspeptin-54 (KP) alone and in combination. Frequent blood sampling to measure plasma gonadotropins and sex steroids was conducted and LH pulsatility was determined using blinded deconvolution analysis.Results:All kisspeptin and naltrexone containing groups potently increased LH and LH pulsatility (P < .001 vs vehicle). NKB alone did not affect gonadotropins. NKB+KP had significantly lower increases in gonadotropins compared with kisspeptin alone (P < .01). Naltrexone+KP was the only group to significantly increase LH pulse amplitude (P < .001 vs vehicle).Conclusions:Our results suggest significant interactions between the KNDy neuropeptides on LH pulsatility and gonadotropin release in humans. This has important implications for improving our understanding of GnRH pulse generation in humans.

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2212 The VWF A1 domain contains the binding site for the platelet receptor glycoprotein (GP)Ib receptor, and this interaction forms the initial tethering event to capture platelets at sites of injury under high shear stress. The VWF-A1:GPIbα interaction has a high association and dissociation rate and as such platelets translocate along the VWF surface until stable attachment can occur. It has been previously shown that under static conditions the VWF D'D3 domains shield the A1 from interaction with GPIbα, however it has not been established if this occurs under conditions of shear stress. To this end we constructed VWF fragments spanning the D'-A3 domains and the A1A2A3 domains. These were expressed and purified and the ability of these constructs to interact with platelets was analysed in an in vitro flow assays system. Purified and fluorescently labelled platelets resuspended in plasma free blood were perfused over immobilised VWF at a range of shear rates (400–2000s−1), and real time movies of the interactions captured. Interestingly, platelets translocated slower across VWF-A1A2A3, with lower rolling velocities compared to VWF-D'A3 at all shear rates tested. Significantly the dissociation rate constant (koff) of the transient tethers formed between GPIbα and VWF was similar for both constructs, indicating that that the observed difference in platelet rolling velocity is not due to an alteration in bond lifetime. Frame-by-frame analysis of platelet translocation demonstrated that platelets paused more often on VWF lacking the D'D3 domains and therefore translocated a shorter distance in a set time when compared to VWF D'A3 resulting in decreased rolling velocities. We hypothesise that the accessibility of the GPIb binding site in the A1 domain is increased in the absence of the D'D3 domains, resulting in more interactions. Together these data demonstrate the D'D3 domains are able to shield the A1 domain under shear stress conditions. Disclosures: No relevant conflicts of interest to declare.

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