Integrin β3 Haploinsufficiency Modulates Serotonin Transport and Antidepressant-Sensitive Behavior in Mice

Converging lines of evidence have identified genetic interactions between the serotonin transporter (SERT) gene and ITGB3, which encodes the β3 subunit that forms the αIIbβ3 and αvβ3 integrin receptor complexes. Here we examine the consequences of haploinsufficiency in the mouse integrin β3 subunit gene (Itgb3) on SERT function and selective 5-hydroxytryptamine (5-HT) reuptake inhibitor (SSRI) effectiveness in vivo. Biochemical fractionation studies and immunofluorescent staining of murine brain slices reveal that αvβ3 receptors and SERTs are enriched in presynaptic membranes from several brain regions and that αvβ3 colocalizes with a subpopulation of SERT-containing synapses in raphe nuclei. Notably, we establish that loss of a single allele of Itgb3 in murine neurons is sufficient to decrease 5-HT uptake by SERT in midbrain synaptosomes. Pharmacological assays to elucidate the αvβ3-mediated mechanism of reduced SERT function indicate that decreased integrin β3 subunit expression scales down the population size of active SERT molecules and, as a consequence, lowers the effective dose of SSRIs. These data are consistent with the existence of a subpopulation of SERTs that are tightly modulated by integrin αvβ3 and significantly contribute to global SERT function at 5-HT synapses in the midbrain. Importantly, our screen of a normal human population for single nucleotide polymorphisms in human ITGB3 identified a variant associated with reductions in integrin β3 expression levels that parallel our mouse findings. Thus, polymorphisms in human ITGB3 may contribute to the differential responsiveness of select patients to SSRIs.     

Single‐dose administration of clenbuterol is detectable in dried blood spots

Clenbuterol is a β₂‐agonist prescribed for asthmatic patients in some countries. Based on its anabolic and lipolytic effects observed in studies on rodents and in livestock destined for food production, clenbuterol is abused by bodybuilders and athletes seeking leanness. Urinary clenbuterol analysis is part of routine doping analysis. However, the collection of urine samples is time‐consuming and can be intimidating for athletes. Dried blood spot (DBS) appears attractive as an alternative matrix, but the detectability of clenbuterol in humans through DBS has not been investigated. This study evaluated if clenbuterol could be detected in DBS and urine collected from six healthy men after oral intake of 80 μg clenbuterol. The DBS and urine samples were collected at 0, 3, 8, 24, and 72 h post‐ingestion, with additional urine collections on days 7 and 10. Using LC–MS/MS, it was shown that clenbuterol could be detected in all DBS samples for 24 h post‐ingestion and with 50% sensitivity 3 days after ingestion. The DBS method was 100% specific. Evaluation of analyte stability showed that clenbuterol is stable in DBS for at least 365 days at room temperature when using desiccant and avoiding light exposure. In urine, clenbuterol was detectable for at least 7–10 days after ingestion. Urinary clenbuterol concentrations below 5 ng/mL were present in some subjects 24 h after administration. Collectively, these data indicate that DBS are suitable for routine doping control analysis of clenbuterol with a detection window of at least 3 days after oral administration of 80 μg.     

Platelet glycoproteins IIb and IIIa as a calcium channel in liposomes

Human platelet membrane glycoproteins IIb and IIIa (GPIIb and IIIa) were incorporated into phospholipid vesicles by the reverse-phase technique to assess the ability of GPIIb and IIIa to function as a Ca2+ channel. Movement of Ca2+ across the lipid bilayer was quantitated by injection of proteoliposomes with encapsulated Fura-2 into Ca2+ buffers and measurement of Fura-2 fluorescence as an indicator of Ca2+ influx. Reciprocally, to assess the function of proteins in an inside-out orientation, Ca2+-loaded vesicles were injected into Ca2+-free buffer and Ca2+ efflux monitored by a calcium electrode. Incorporation of the IIb-IIIa complex produced significant facilitation of Ca2+ movement across the lipid bilayer. No net transmembrane Ca2+ movement was seen with dissociated IIb and IIIa. Movement of Ca2+ was proportional to the transmembrane Ca2+ gradient. Ca2+ movement into the vesicles was inversely proportional to extravesicular NaCl from 25 to 150 mmol/L, analogous to several studies in the intact platelet. Adenosine triphosphate had no effect on Ca2+ movement into or out of the vesicles. Specific inhibition of a Ca2+ shift into the vesicles was seen with M148, a monoclonal antibody to IIb/IIIa, while no inhibition was observed with a panel of other anti-IIb/IIIa monoclonal antibodies. This suggests that a specific site on the complex or orientation of the complex is essential for calcium channel function. These data demonstrate that the GPIIb/IIIa complex can serve as a passive Ca2+ channel across a phospholipid bilayer and has the potential to play a role in Ca2+ flux across the platelet plasma membrane.     

Unconscious discrimination of social cues from eye whites in infants

Human eyes serve two key functions in face-to-face social interactions: they provide cues about a person’s emotional state and attentional focus (gaze direction). Both functions critically rely on the morphologically unique human sclera and have been shown to operate even in the absence of conscious awareness in adults. However, it is not known whether the ability to respond to social cues from scleral information without conscious awareness exists early in human ontogeny and can therefore be considered a foundational feature of human social functioning. In the current study, we used event-related brain potentials (ERPs) to show that 7-mo-old infants discriminate between fearful and nonfearful eyes (experiment 1) and between direct and averted gaze (experiment 2), even when presented below the perceptual threshold. These effects were specific to the human sclera and not seen in response to polarity-inverted eyes. Our results suggest that early in ontogeny the human brain detects social cues from scleral information even in the absence of conscious awareness. The current findings support the view that the human eye with its prominent sclera serves critical communicative functions during human social interactions.Eyes play a key role in human social encounters, as they are critically involved in perceiving others as having minds (1), in attributing mental states to others (2), and in social coordination during face-to-face interactions (3). The presence of eyes has also been shown to increase cooperative behavior in laboratory and in real-world contexts (2, 4–7). The human eye is unique in that it is characterized by a prominent white sclera several times larger than that of other primates (8, 9), which allows for the efficient communication and detection of social information. It is thought that the human sclera is adapted to facilitate interpersonal communication and cooperative interactions among humans (10). When humans observe others’ faces, eyes are typically the first features that are scanned for information (11), and, compared with other primates, humans show a stronger focus on the eye region than on other parts of the face when scanning faces (12, 13). Conversely, failure to devote special attention to the eye region during face perception has been linked to severe social deficits that can, for instance, be observed in autism spectrum disorder (14).One reason why human eyes have such prime importance is that emotion perception, as a vital part of any social interaction, heavily relies on information from the eye region (14). This is especially important for the detection of fear in others, as one of the most basic forms of identifying threatening situations. Fear detection has been observed in response to eyes alone (15, 16). This mechanism operates exceptionally fast (17) and occurs irrespective of conscious awareness (15). On a neural level, the processing of fearful eyes critically depends on the amygdala. Depending on the context (18, 19), fearful eyes can elicit an enhanced activation of the amygdala (20), even if not perceived consciously (15). Patients with bilateral amygdala lesions show deficits in recognizing fear, which disappear when they are instructed to focus on the eye region (21). Furthermore, there is recent evidence to show that the amygdala is involved in reflexively directing attention to the eyes and in predicting gaze to fearful eyes (22, 23).Another important social cue conveyed by the eye is the direction of gaze. Eye gaze can inform us about another person’s attentional focus, thereby providing clues about future behavior (24). Critically, eye gaze and emotion perception have been shown to powerfully interact. For example, fearful eyes elicit stronger behavioral and neural responses when averted from than when directed at an observer (25, 26). This presumably relates to the fact that averted fearful eyes inform an observer about a potential danger in the environment (clear threat), whereas directed fearful eyes signal fear of the observer (ambiguous threat). At the brain level, this also relies on the amygdala, as reflected in a differential activation for direct compared with averted gaze (25, 27). Furthermore, behavioral studies suggest that similar to emotion processing, eye gaze discrimination operates even in the absence of conscious awareness (28).Attending and responding to eyes is thought to play a vital role in the early development of social skills (29). From birth, infants respond sensitively to human eyes: Newborns prefer direct gaze faces over averted gaze faces (30) and even show a rudimentary form of gaze following (31). Newborns’ sensitivity to eyes has been shown to be specific to the human sclera, as behavioral preferences disappear when the contrast polarity of the eye is reversed (32). Nevertheless, the ability to attend to the eyes and follow gaze improves considerably over the course of the first year of life and is viewed as an important marker of healthy social development (33, 34). Indeed, orienting to the eyes is present early in infancy but declines between 2 and 6 mo in infants later diagnosed with autism (29). With respect to responding to emotional information, newborns also show a basic sensitivity to (familiar) emotional facial expressions for which they may also use eye cues (30, 35, 36). However, it is not until the age of 7 mo that they show a robust attentional bias to fear, as reflected in their neural and behavioral responses (37–41). The developmental emergence of this fear bias has been linked to the maturation of frontolimbic circuits (42–45) and occurs at a point in development when infants begin to first experience fear themselves (46, 47). Despite our growing understanding of the developmental origins of emotion and gaze processing in humans, some fundamental questions concerning the exact nature of this ability remain unanswered.In the present study we therefore addressed two key questions, which are essential to understanding the mechanisms that underpin sensitive responding to human eyes in infants. First, we asked whether infants’ detection of social cues such as fear and gaze from eyes occurs in the absence of conscious awareness. Second, we examined whether the detection of these social cues can be seen in response to scleral information alone. To address these questions, we conducted two experiments, based on an established paradigm from adult literature (15), which investigated whether the infant brain can discriminate between fearful and nonfearful eyes (experiment 1) and between direct and averted fearful eyes (experiment 2), even if the stimuli are not perceived consciously. We hypothesized that if the eyes indeed serve a critical function in human social communication, then the unconscious detection of social cues from scleral information should be evident early in ontogeny. Specifically, according to our hypothesis, using event-related brain potentials (ERPs), we expected infants to show evidence for neural discrimination between fearful and nonfearful human eyes (experiment 1) and direct and averted gaze (experiment 2).     

《英国非酒精性脂肪性肝炎肝移植指南》导读

非酒精性脂肪性肝炎（non—alcoholicsteatohepatitis,NASH）现已成为肝移植愈来愈重要的基础肝病。鉴于晚期NASH患者常并存多种影响肝移植转归的临床问题,而至今尚无针对NASH患者进行肝移植的评估和治疗指南,为此英国移植学会（British Transplant Society,BTS）邀请相关专家制定了指南,以指导肝移植前后NASH患者的处理。     

Impaired nitric oxide synthase signaling dissociates social investigation and aggression

A combination of social withdrawal and increased aggression is characteristic of several mental disorders. Most previous studies have investigated the neurochemical bases of social behavior and aggression independently, as opposed to how these behaviors are regulated in concert. Neuronal nitric oxide synthase (nNOS) produces gaseous nitric oxide, which functions as a neurotransmitter and is known to affect several types of behavior including mating and aggression. Compared with wild-type mice, we observed that nNOS knockout mice showed reduced behavioral responses to an intruder behind a wire barrier. Similar results were observed in mice treated with the selective nNOS inhibitor 3-bromo-7-nitroindazole (3BrN). In habituation-dishabituation tests, treatment with 3BrN did not block recognition of male urine but did attenuate investigation time compared with oil-treated animals. Finally, nNOS knockout mice and 3BrN treated mice were significantly more aggressive than wild-type and oil-treated males, respectively. In general, these behavioral effects are less pronounced in pair-housed males compared with singly-housed males. Thus, nNOS inhibition results in a phenotype that displays reduced social investigation and increased aggression. These data suggest that further study of nNOS signaling is warranted in mental disorders characterized by social withdrawal and increased aggression.