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Arthroscopically assisted techniques for the treatment of foveal triangular fibrocartilage complex (TFCC) injuries offer a less invasive option. Reports of the ulnar tunnel technique on a larger patient population are needed. This prospective cohort study of 44 patients aimed to evaluate the clinical and patient-reported outcome after arthroscopic foveal re-attachment using a novel, modified ulnar tunnel technique. Furthermore, preoperative magnetic resonance imaging findings were compared with the findings from the arthroscopic evaluation. History of ulnar sided wrist pain, positive fovea-sign at the clinical examination and positive hook test at the surgery were the main inclusion criteria for the study. Pain, grip strength, wrist motion and patient-reported outcomes were assessed pre-and postoperatively. The follow-up of this study was 31 months (range 18-48). No complications occurred during the surgery. All outcomes improved besides the range of motion, which remained unchanged. Pain on a visual analogue scale was 63 before, and 14 after the surgery (p = .0004). Pre- and postoperative values of Disability of Arm, Shoulder and Hand Questionnaire were 41/6, respectively (p=.007). Grip strength, measured in Kilogram-force were 29 and 36, pre-and postoperatively (p = .0004). Conspicuously, all patients achieved stability. Six patients needed re-operation, three for renewed injury. Thirty-nine of 44 patients scored excellent or good on the satisfaction score. We found the devised method to be with fewer complications and with favourable results compared with other techniques for the treatment of TFCC injuries.

Cleavage of amyloid precursor protein (APP) by β-secretase BACE1 initiates the production and accumulation of neurotoxic amyloid-β peptides, which is widely considered an essential pathogenic mechanism in Alzheimer's disease (AD). Here, we report that BACE1 is essential for normal auditory function. Compared with wild-type littermates, BACE1−/−mice of either sex exhibit significant hearing deficits, as indicated by increased thresholds and reduced amplitudes in auditory brainstem responses (ABRs) and decreased distortion product otoacoustic emissions (DPOAEs). Immunohistochemistry revealed aberrant synaptic organization in the cochlea and hypomyelination of auditory nerve fibers as predominant neuropathological substrates of hearing loss in BACE1−/−mice. In particular, we found that fibers of spiral ganglion neurons (SGN) close to the organ of Corti are disorganized and abnormally swollen. BACE1 deficiency also engenders organization defects in the postsynaptic compartment of SGN fibers with ectopic overexpression of PSD95 far outside the synaptic region. During postnatal development, auditory fiber myelination in BACE1−/−mice lags behind dramatically and remains incomplete into adulthood. We relate the marked hypomyelination to the impaired processing of Neuregulin-1 when BACE1 is absent. To determine whether the cochlea of adult wild-type mice is susceptible to AD treatment-like suppression of BACE1, we administered the established BACE1 inhibitor NB-360 for 6 weeks. The drug suppressed BACE1 activity in the brain, but did not impair hearing performance and, upon neuropathological examination, did not produce the characteristic cochlear abnormalities of BACE1−/−mice. Together, these data strongly suggest that the hearing loss of BACE1 knock-out mice represents a developmental phenotype.SIGNIFICANCE STATEMENTGiven its crucial role in the pathogenesis of Alzheimer's disease (AD), BACE1 is a prime pharmacological target for AD prevention and therapy. However, the safe and long-term administration of BACE1-inhibitors as envisioned in AD requires a comprehensive understanding of the various physiological functions of BACE1. Here, we report that BACE1 is essential for the processing of auditory signals in the inner ear, as BACE1-deficient mice exhibit significant hearing loss. We relate this deficit to impaired myelination and aberrant synapse formation in the cochlea, which manifest during postnatal development. By contrast, prolonged pharmacological suppression of BACE1 activity in adult wild-type mice did not reproduce the hearing deficit or the cochlear abnormalities of BACE1 null mice.

Background Enhanced GABA activity in the brain and a hyperactive hypothalamic-pituitary-gonadal axis are associated with polycystic ovary syndrome (PCOS), the most common form of anovulatory infertility. Women with PCOS exhibit elevated cerebrospinal fluid GABA levels and preclinical models of PCOS exhibit increased GABAergic input to GnRH neurons, the central regulators of reproduction. The arcuate nucleus (ARN) is postulated as the anatomical origin of elevated GABAergic innervation; however, the functional role of this circuit is undefined. Methods We employed a combination of targeted optogenetic and chemogenetic approaches to assess the impact of acute and chronic ARN GABA neuron activation. Selective acute activation of ARN GABA neurons and their fiber projections was coupled with serial blood sampling for luteinizing hormone secretion in anesthetized male, female and prenatally androgenised (PNA) mice modelling PCOS. In addition, GnRH neuron responses to ARN GABA fiber stimulation were recorded in ex vivo brain slices. Chronic activation of ARN GABA neurons in healthy female mice was coupled with reproductive phenotyping for PCOS-like features. Findings Acute stimulation of ARN GABA fibers adjacent to GnRH neurons resulted in a significant and long-lasting increase in LH secretion in male and female mice. The amplitude of this response was blunted in PNA mice, which also exhibited a blunted LH response to GnRH administration. Infrequent and variable GABAA-dependent changes in GnRH neuron firing were observed in brain slices. Chronic activation of ARN GABA neurons in healthy females impaired estrous cyclicity, decreased corpora lutea number and increased circulating testosterone levels. Interpretation ARN GABA neurons can stimulate the hypothalamic-pituitary axis and chronic activation of ARN GABA neurons can mimic the reproductive deficits of PCOS in healthy females. Unexpectedly blunted HPG axis responses in PNA mice may reflect a history of high frequency GnRH/LH secretion and reduced LH stores, but also raise questions about impaired function within the ARN GABA population and the involvement of other circuits.

Funder: Health Research Council of New Zealand; FundRef: http://dx.doi.org/10.13039/501100001505, Funder: Wellcome Trust; FundRef: http://dx.doi.org/10.13039/100004440, The necessity and functional significance of neurotransmitter co-transmission remains unclear. The glutamatergic ‘KNDy’ neurons co-express kisspeptin, neurokinin B (NKB), and dynorphin and exhibit a highly stereotyped synchronized behavior that reads out to the gonadotropin-releasing hormone (GnRH) neuron dendrons to drive episodic hormone secretion. Using expansion microscopy, we show that KNDy neurons make abundant close, non-synaptic appositions with the GnRH neuron dendron. Electrophysiology and confocal GCaMP6 imaging demonstrated that, despite all three neuropeptides being released from KNDy terminals, only kisspeptin was able to activate the GnRH neuron dendron. Mice with a selective deletion of kisspeptin from KNDy neurons failed to exhibit pulsatile hormone secretion but maintained synchronized episodic KNDy neuron behavior that is thought to depend on recurrent NKB and dynorphin transmission. This indicates that KNDy neurons drive episodic hormone secretion through highly redundant neuropeptide co-transmission orchestrated by differential post-synaptic neuropeptide receptor expression at the GnRH neuron dendron and KNDy neuron.

Acute stress is a potent suppressor of pulsatile luteinizing hormone (LH) secretion, but the mechanisms through which corticotrophin-releasing hormone (CRH) neurons inhibit gonadotropin-releasing hormone (GnRH) release remain unclear. The activation of paraventricular nucleus (PVN) CRH neurons with Cre-dependent hM3Dq in Crh-Cre female mice resulted in the robust suppression of pulsatile LH secretion. Channelrhodopsin (ChR2)-assisted circuit mapping revealed that PVN CRH neuron projections existed around kisspeptin neurons in the arcuate nucleus (ARN) although many more fibers made close appositions with GnRH neuron distal dendrons in the ventral ARN. Acutely prepared brain slice electrophysiology experiments in GnRH- green fluorescent protein (GFP) mice showed a dose-dependent (30 and 300 nM CRH) activation of firing in ~20% of GnRH neurons in both intact diestrus and ovariectomized mice with inhibitory effects being uncommon (

Homeostatic processes like metabolism and reproduction are tightly regulated by neural circuits, and any disruption of these neural circuits causes energy imbalance and infertility, respectively. Furthermore, in conditions of energy imbalance, such as anorexia or obesity, there is also reproductive dysfunction. This causal relationship between metabolism and reproduction, strongly suggests an interdependence of these neuronal networks. In order to better understand the mechanisms underlying infertility caused by metabolic imbalance, it is important to identify the specific circuitry governing the coordination of energy balance and reproductive function. Neuropeptide Y (NPY) / Agouti related peptide (AgRP) expressing neurons in the arcuate nucleus (ARN) are likely to play an important role as they are crucial in regulating food intake and also affect gonadotropin-releasing hormone (GnRH) neuronal activity and luteinizing hormone (LH) secretion. However, the precise impact of the ARN NPY/AgRP circuit on GnRH neuron activity and fertility remains unclear. To assess this, we used the stimulatory DREADD in AgRP-Cre mice to specifically activate ARN NPY/AgRP neurons and measured pulsatile LH secretion, as a readout of GnRH neuronal activity, in conscious male and female mice. We found that activation of NPY/AgRP neurons by injection of the DREADD ligand, clozapine-N-oxide (CNO), decreased post-castration LH pulse secretion in both sexes, suggesting a slowing of GnRH pulse generation. To map the specific circuit associated with slowing of LH secretion following ARN NPY/AgRP neuron activation, region specific activation of NPY/AgRP fibres was achieved with optogenetics. Selective optogenetic stimulation of NPY/AgRP terminals surrounding GnRH neuron cell bodies in the rostral preoptic area (rPOA) was capable of decreasing GnRH neuron activity in ex vivo slices and significantly decreased LH pulsatility in conscious animals, indicating a functional ARN NPY/AgRP to GnRH neuron circuit capable of slowing pulse generation. Chemogenetic and optogenetic activation of ARN NPY/AgRP neurons was also able to significantly reduce LH pulse frequency in a prenatally androgenised (PNA) model of polycystic ovary syndrome that exhibits high LH pulse frequency, thereby demonstrating therapeutic potential. However, chronic activation of ARN NPY/AgRP neurons with CNO delivery in drinking water over 2 weeks did not ameliorate the PCOS-like reproductive pathology in PNA mice. Together, these data show that activation of ARN NPY/AgRP neurons can slow GnRH/LH pulse generation, potentially through a direct circuit to GnRH neurons in the rPOA. These findings identify a specific mechanism by which ARN NPY/AgRP neurons mediate nutritional infertility and highlight the therapeutic potential of modulating ARN NPY/AgRP activity in infertile conditions associated with high GnRH/ LH pulsatility. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

Kv7.1 (KCNQ1) coassembles with KCNE1 to generate the cardiac IKs-channel. Gain- and loss-of-function mutations in KCNQ1 are associated with cardiac arrhthymias, highlighting the importance of modulating IKs activity for cardiac function. Here, we report proteolysis of Kv7.1 as an irreversible posttranslational modification. The identification of two C-terminal fragments of Kv7.1 led us to identify an aspartate critical for the generation of one of the fragments and caspases as responsible for mediating proteolysis. Activating caspases reduces Kv7.1/KCNE1 currents, which is abrogated in cells expressing caspase-resistant channels. Enhanced cleavage of Kv7.1 can be detected for the LQT mutation G460S, which is located adjacent to the cleavage site, whereas a calmodulin-binding-deficient mutation impairs cleavage. Application of apoptotic stimuli or doxorubicin-induced cardiotoxicity provokes caspase-mediated cleavage of endogenous IKs in human cardiomyocytes. In summary, caspases are novel regulatory components of IKs channels that may have important implications for the molecular mechanism of doxorubicin-induced cardiotoxicity., Anne Strigli et al. report that the voltage-gated potassium channel Kv7.1 undergoes caspase-mediated proteolytic cleavage, which reduces its cardiac activity. Their findings implicate caspases as regulators of the IKs channel complex, which may have implications for understanding drug-induced cardiotoxicity.

Cues that predict the availability of food rewards influence motivational states and elicit food-seeking behaviors. If a cue no longer predicts food availability, then animals may adapt accordingly by inhibiting food-seeking responses. Sparsely activated sets of neurons, coined “neuronal ensembles,” have been shown to encode the strength of reward–cue associations. Although alterations in intrinsic excitability have been shown to underlie many learning and memory processes, little is known about these properties specifically on cue-activated neuronal ensembles. We examined the activation patterns of cue-activated orbitofrontal cortex (OFC) and nucleus accumbens (NAc) shell ensembles using wild-type andFos-GFPmice, which express green fluorescent protein (GFP) in activated neurons, after appetitive conditioning with sucrose and extinction learning. We also investigated the neuronal excitability of recently activated, GFP+ neurons in these brain areas using whole-cell electrophysiology in brain slices. Exposure to a sucrose cue elicited activation of neurons in both the NAc shell and OFC. In the NAc shell, but not the OFC, these activated GFP+ neurons were more excitable than surrounding GFP− neurons. After extinction, the number of neurons activated in both areas was reduced and activated ensembles in neither area exhibited altered excitability. These data suggest that learning-induced alterations in the intrinsic excitability of neuronal ensembles is regulated dynamically across different brain areas. Furthermore, we show that changes in associative strength modulate the excitability profile of activated ensembles in the NAc shell.SIGNIFICANCE STATEMENTSparsely distributed sets of neurons called “neuronal ensembles” encode learned associations about food and cues predictive of its availability. Widespread changes in neuronal excitability have been observed in limbic brain areas after associative learning, but little is known about the excitability changes that occur specifically on neuronal ensembles that encode appetitive associations. Here, we reveal that sucrose cue exposure recruited a more excitable ensemble in the nucleus accumbens, but not orbitofrontal cortex, compared with their surrounding neurons. This excitability difference was not observed when the cue's salience was diminished after extinction learning. These novel data provide evidence that the intrinsic excitability of appetitive memory-encoding ensembles is regulated differentially across brain areas and adapts dynamically to changes in associative strength.

β-site APP-cleaving enzyme 1 (BACE1) has become infamous for its pivotal role in the pathogenesis of Alzheimer's disease (AD). Consequently, BACE1 represents a prime target in drug development. Despite its detrimental involvement in AD, it should be quite obvious that BACE1 is not primarily present in the brain to drive mental decline. In fact, additional functions have been identified. In this review, we focus on the regulation of ion channels, specifically voltage-gated sodium and KCNQ potassium channels, by BACE1. These studies provide evidence for a highly unexpected feature in the functional repertoire of BACE1. Although capable of cleaving accessory channel subunits, BACE1 exerts many of its physiologically significant effects through direct, non-enzymatic interactions with main channel subunits. We discuss how the underlying mechanisms can be conceived and develop scenarios how the regulation of ion conductances by BACE1 might shape electric activity in the intact and diseased brain and heart.

The β-secretase BACE1 is widely known for its pivotal role in the amyloidogenic pathway leading to Alzheimer's disease, but how its action on transmembrane proteins other than the amyloid precursor protein affects the nervous system is only beginning to be understood. We report here that BACE1 regulates neuronal excitability through an unorthodox, nonenzymatic interaction with members of the KCNQ (Kv7) family that give rise to the M-current, a noninactivating potassium current with slow kinetics. In hippocampal neurons from BACE1−/−mice, loss of M-current enhanced neuronal excitability. We relate the diminished M-current to the previously reported epileptic phenotype of BACE1-deficient mice. In HEK293T cells, BACE1 amplified reconstituted M-currents, altered their voltage dependence, accelerated activation, and slowed deactivation. Biochemical evidence strongly suggested that BACE1 physically associates with channel proteins in a β-subunit-like fashion. Our results establish BACE1 as a physiologically essential constituent of regular M-current function and elucidate a striking new feature of how BACE1 impacts on neuronal activity in the intact and diseased brain.

Topically applied camphor elicits a sensation of cool, but nothing is known about how it affects cold temperature sensing. We found that camphor sensitizes a subpopulation of menthol-sensitive native cutaneous nociceptors in the mouse to cold, but desensitizes and partially blocks heterologously expressed TRPM8 (transient receptor potential cation channel subfamily M member 8). In contrast, camphor reduces potassium outward currents in cultured sensory neurons and, in cold nociceptors, the cold-sensitizing effects of camphor and menthol are additive. Using a membrane potential dye-based screening assay and heterologously expressed potassium channels, we found that the effects of camphor are mediated by inhibition of Kv7.2/3 channels subtypes that generate the M-current in neurons. In line with this finding, the specific M-current blocker XE991 reproduced the cold-sensitizing effect of camphor in nociceptors. However, the M-channel blocking effects of XE991 and camphor are not sufficient to initiate cold transduction but require a cold-activated inward current generated by TRPM8. The cold-sensitizing effects of XE991 and camphor are largest in high-threshold cold nociceptors. Low-threshold corneal cold thermoreceptors that express high levels of TRPM8 and lack potassium channels are not affected by camphor. We also found that menthol--like camphor--potently inhibits Kv7.2/3 channels. The apparent functional synergism arising from TRPM8 activation and M-current block can improve the effectiveness of topical coolants and cooling lotions, and may also enhance TRPM8-mediated analgesia., Funding for this project was obtained through the German Research Council (DFG): Zi1172/1-1 (K.Z.), Zi1172/2-1 (K.Z., P.W.R.) and KFO130/TP7 (P.W.R.), the Dr Ernst und Anita Bauer-Foundation (S.S.), the Erika Giehrl-Foundation (F.T.), the STAEDTLER Foundation (K.Z., P.W.R.), the Australian Research Council ARC LIEF grant for the FLIPR TETRA (R.J.L.), a National Health and Medical Research Council Project Grant (I.V.), and the Go8 Australia-Germany Joint Research Co-operation Scheme (I.V., K.Z.).