, 2001) were maintained on a C57Bl/6 background Plxnd1+/− mice (

, 2001) were maintained on a C57Bl/6 background. Plxnd1+/− mice ( Gu et al., 2005), Npn1 mice ( Gu et al., 2003), and VegflacZ mice ( Miquerol et al., 1999) were maintained on an outbred Swiss Webster background. Sema3e+/− mice were maintained on an 129SVE background. Ngn1 ( Ma et al., 1998) and Ngf ( Crowley et al., 1994) knockout embryos were obtained from Dr. Quifu Ma (Harvard Medical School) and Dr. Rejji Kuruvilla (Johns Hopkins University), respectively. Swiss Selleckchem INCB024360 Webster, C57Bl/6, and 129SVE wild-type mice were obtained from Taconic Farms. All animals were treated

according to institutional and National Institutes of Health guidelines approved by the Institutional Animal Care and Use Committee at Harvard Medical School. Embryos were removed,

immediately frozen in liquid nitrogen, and sectioned at 16 μm using a cryostat (Leica). Sections were fixed in 4% paraformaldehyde (PFA) for 5 min and briefly washed in 1× PBS several times at room temperature. After washing, sections were blocked in 1× PBS containing 0.1% Triton X-100 (PBST) and 10% normal goat serum for 1 hr and then Sirolimus nmr incubated with primary antibodies in blocking buffer at 4°C overnight. For Plexin-D1 immunohistochemisty, embryos were fixed in 4% PFA in 0.1 M phosphate buffer (pH 7.5) for 2 hr and equilibrated in 30% sucrose at 4°C overnight. The antibodies used are: α-neurofilament (1:100; Item No. 2H3, Developmental Studies Hybridoma Bank), α-PECAM (1:500; 553370, BD Pharmingen), α-Plexin-D1 (1:6,000, a gift from Dr. Yutaka Yoshida, Cincinnati Children’s Hospital), and α-TrkA (1:500; 06-574, Millipore). After washing in 1× PBST for 5 min three times, sections were incubated in Alexa Fluor-conjugated secondary antibodies (1:1,000, Invitrogen) for 1 hr, then washed several times in PBST, and mounted with Fluoromount G (Electron Microscopy Sciences). Immunostained sections were analyzed by fluorescence microscopy using a Nikon Eclipse 80i microscope equipped with a all Nikon DS-2 digital camera. Images were processed using Adobe Photoshop and ImageJ (National Institutes

of Health). For whole-mount whisker follicle staining, embryos were fixed in 4% PFA for 6 hr and equilibrated in 30% sucrose at 4°C overnight. Embryo snout areas were sectioned at 100 μm using a cryostat (Leica) and blocked in 1× PBST, 10% DMSO, and 5% normal goat serum for 1 hr, and then incubated with primary antibodies in blocking buffer at room temperature for 2 days. The antibodies used were α-neurofilament (1:50; 2H3) and α-VE-cadherin (1:100; ab33168, Abcam). After washing in 1× PBST for 1 hr five times, sections were incubated in Alexa Fluor-conjugated secondary antibodies (1:500, Invitrogen), diluted in the blocking buffer for 1 day, then washed several times in PBST, and dehydrated with 100% methanol. Before mounting, sections were cleared with benzyl alcohol and benzyl benzoate mixture.

, 2010 and Doyon

, 2010 and Doyon BI-2536 and Benali, 2005). Studies that examined the neuronal mechanisms involved in the slow stage of motor skill learning typically had subjects learn a motor skill over several weeks and scanned them on different occasions throughout the training period (Karni et al., 1995, Floyer-Lea and Matthews, 2005, Coynel et al., 2010 and Lehéricy et al., 2005). Slow learning is associated with increased activation in M1 (Floyer-Lea and Matthews, 2005), primary somatosensory cortex (Floyer-Lea and Matthews, 2005), SMA (Lehéricy et al., 2005), and putamen

(Lehéricy et al., 2005 and Floyer-Lea and Matthews, 2005), as well as decreased activation in lobule VI of the cerebellum (Figure 4; Lehéricy

et al., 2005). Thus, progress from early to late stages of motor skill learning is characterized by a shift in fMRI activation from anterior to more posterior regions Tyrosine Kinase Inhibitor Library price of the brain (Floyer-Lea and Matthews, 2005), a pattern also reported when learning nonmotor tasks, which is thought to reflect a progressive decrease in reliance on attentional resources and executive function (Kelly and Garavan, 2005). Progressing from fast to slow motor skill learning is also associated with a shift in fMRI activation from associative to sensorimotor striatum (Coynel et al., 2010 and Lehéricy et al., 2005), thought to contribute to slow learning of the motor component of sequences (Hikosaka et al., 2002a). Slow learning has been linked with larger-scale functional reorganization as well. A recent study tracked functional connectivity using fMRI over a period of 4 weeks of training on an explicit motor sequence task (Coynel et al., 2010). Early learning was associated with increased integration, a metric reflecting functional interactions among several brain regions, of a premotor-associative

striatum-cerebellar network. During slow learning, TCL on the other hand, the authors reported decreased integration in this premotor-associative striatum-cerebellar network but stable connectivity within the M1-sensorimotor striatum-cerebellar network, largely consistent with data emerging from regional fMRI analysis (Floyer-Lea and Matthews, 2005 and Lehéricy et al., 2005). Engagement of neurons in the sensorimotor striatum during later stages of learning has been well documented in animal models (Miyachi et al., 2002 and Yin et al., 2009) and has been proposed as a substrate for the acquisition of habitual and automatic behavior (Yin et al., 2004 and Yin et al., 2009). For example, in vivo recordings in behaving rodents revealed that the sensorimotor striatum is engaged later in training, when performance in an accelerated rotarod task asymptoted (Yin et al., 2009).

Minor changes in early patterning events have been shown to under

Minor changes in early patterning events have been shown to underlie large-scale morphogenetic rearrangements of the body plan ( Carroll, 2008).

Consistently, relatively small variations in Shh and Wnt signaling pathways participated in the rapid evolution of the brain in fish populations located in distinct natural environments ( Menuet et al., 2007 and Sylvester et al., 2010). Our results open the intriguing possibility that similar mechanisms may have governed the evolution of brain connectivity, via local changes in the expression of highly conserved guidance cues. What may modulate Slit2 expression in distinct species? One possibility is that upstream transcriptional regulators of INCB024360 order Slit2 may be differentially expressed in mammals and reptiles/birds. A nonexclusive alternative is that Slit2 learn more cis-regulatory sequences may have undergone evolutionary changes, leading to species-specific variations in gene expression. It has been shown that modifications of cis-regulatory sequences constitute a powerful drive for the evolution of complex patterns by modulating

spatially and temporally the transcriptional regulation of conserved genetic cascades ( Carroll, 2008). Therefore, it will be of great interest to investigate whether similar mechanisms are involved in the species-specific expression of Slit2, and may thus have participated in the evolution of brain wiring. The telencephalon of vertebrates has undergone major changes that include a quantitative increase in both neurogenesis and cell migration, and which have led to the development of the six-layered neocortex of living mammals (Kriegstein et al., 2006). If the emergence of the neocortex is directly related to intrinsic changes in the dorsal telencephalon, it is also linked to global modifications of connectivity, such as

the appearance of a large internal capsule. Our study shows that small changes in neuronal cell migration at intermediate targets have been essential to create an opportunity for this axonal highway, acting in parallel with cortical evolution to promote the functional emergence of the mammalian neocortex. What may be the selective advantages of oxyclozanide an internal trajectory of TAs? First, the internal path is associated with the formation of a large fan-shaped thalamic projection that radiates along the entire rostrocaudal axis as it enters the telencephalon. This feature is highly divergent from the reptilian TAs, which navigate as a compact axonal tract as they enter the subpallium. As such, the internal path may allow both the channeling of a large number of axons directly to the neocortex—creating an axonal highway—as well as the early “spreading” of thalamic projections and the entire covering of an expanding mammalian neocortex—creating a capsule versus a peduncle.

Extensive research has been performed over the years to investiga

Extensive research has been performed over the years to investigate why humans choose one particular manner of performing a task out of the infinite number possible. Initially, this has focused on reaching trajectories that tend to exhibit roughly straight-line paths with bell-shaped speed profiles, although certain movements have some path curvature depending on gravitational constraints (Atkeson and Hollerbach, 1985) or visual feedback (Wolpert et al., 1994). The majority of planning models have been placed within the framework of optimizing a cost. The idea is that a scalar value, termed cost, is associated with

each way of achieving a task, allowing all possible solutions to be ranked and the one Proteasome activity with the lowest cost selected. Different costs then make different predictions

about the movement trajectory. For example, models that have been able to account for behavioral data include minimizing the rate of change of acceleration of the hand—the so-called minimum jerk model (Flash and Hogan, 1985)—or minimizing the rates of change of torques at the joints—the minimum torque change model (Uno et al., 1989). In these models, the end result is a desired movement. Although noise and environmental disturbances can act to disturb this process, the role of feedback is simply to return the movement back to this desired trajectory. BMN 673 Although able no to account for many features of the empirical trajectories, these models have several features that make them somewhat unattractive in terms of explanatory power. First, it is not clear why the sensorimotor systems should care about costs such as the jerkiness of the hand. Second, even if it did, to optimize this would require measurement of third derivatives of positional information, and for this

to be summed over the movement is not a trivial computation. Third, these models often do not provide information as to what should happen in a redundant system because they only specify endpoint trajectories. Finally, it is hard to generalize these models to arbitrary tasks such as a tennis serve. In an effort to reexamine trajectory control and counter these four problems, a model was developed based on the assumption that there was one key element limiting motor performance, i.e., noise. In particular, motor noise over a reasonable range of motor activity is signal dependent, with the standard deviation of the noise scaling with the mean level of the signal—a constant coefficient of variation. Therefore, for faster, more forceful movements, the noise is greater than for slow movements, naturally leading to the speed-accuracy trade-off.

But a contradicting finding by Shah et al [110] pointed out that

But a contradicting finding by Shah et al. [110] pointed out that β-blocker treatment had no evident beneficial effect on overall survival of patients with common human tumours such as cancers in the lung, breast

and colon, and even produced poorer survival in patients with prostate and pancreatic cancers. Although controversial conclusions are present for the application of β-blockers in cancer treatment, it is noticeable that all of the aforementioned investigations Selleck Y-27632 are population-based retrospective studies which limited the interpretation of the results to some extent. It is time to design clinical trials to test β-blockers in adjuvant treatment of relevant cancers, especially breast cancer. Some important issues need to be considered for future studies including but not limited to blocker selectivity, dose titration and local concentration in tumour mass, β-adrenoceptor RG7420 ic50 expression,

tumour types and stages, and interaction of β-blockers and tumour microenvironment [111] and [112]. Based on preclinical translational data and retrospective analysis, we predict that β-blockers hold considerable promise to treat patients with some cancers in the future as a class of well-defined conventional drug used for cardiovascular diseases in the past decades. Numerous evidences from preclinical and epidemiological studies have implicated that stress hormones or behavioural changes are highly associated with tumour formation and progression. Patients diagnosed

with cancer often endure different degree of stress complicated with high of stress hormones. Likewise nicotine/NNK from cigarette smoke can also stimulate the secretion of stress hormones in cancer patients. All these could Florfenicol stimulate the adrenergic system. It is known that over activation of β-adrenergic system could accelerate cancer development through multiple-step process. An increasing body of information from preclinical investigations and clinical retrospective analysis have shown that β-blockers as a class of drug broadly used for hypertension regulation have great potential to be used to treat cancer patients impacted by psychological stress. However there is no exact conclusion that can be drawn so far from retrospective clinical studies. It is time to launch a well-designed and meticulous clinical trial to affirm the exact role and clinical application of β-blockers in the treatment of cancer patients. On the other hand, it is worthwhile to explore the mechanistic action of β-blockers in the normalization of tumour blood vessels. Indeed it is an emerging and promising therapeutic strategy that vessel remodelling agents in combination with chemotherapeutic drugs are being exploited to treat patients with solid tumours.

This demonstrates that Wnt-induced cell proliferation requires

This demonstrates that Wnt-induced cell proliferation requires

active LEF signaling. Importantly, we found the enhancement of Wnt-induced proliferation by WT-DISC1 or S704C was also significantly reduced upon coexpression of DN-LEF (Figure 1D). These data suggest that learn more the effects of DISC1 and the variants on Wnt-induced cell proliferation do not occur when downstream Wnt signaling is inhibited. Taken together, these data strongly suggest the A83V, R264Q, and L607F variants cannot stimulate cell division/proliferation compared with WT-DISC1 or the S704C variant. To address one potential molecular mechanism to explain these observations, we hypothesized that since DISC1 binds and inhibits GSK3β, the variants might have altered interaction with GSK3β. We overexpressed the different GFP-tagged DISC1 variants in HEK293 cells that were either stimulated or nonstimulated with Wnt3a. Cell lysates were immunoprecipitated with a GSK3β antibody (to UMI-77 immunoprecipitate endogenous GSK3β) and immunoblotted with GFP. We determined that in the absence of Wnt3a stimulation, the R264Q and L607F variants all significantly reduced binding to GSK3β in this assay (Figure 2A), potentially explaining why these variants have reduced signaling. However, the A83V variant did not show reduced binding to GSK3β (Figure 2B). Interestingly, after Wnt3a stimulation, we found that R264Q, L607F, and the A83V variants had reduced binding to GSK3β (Figure 2B). Together these data

suggest that the A83V, R264Q and L607F variants all have reduced binding to GSK3β, while S704C binds as well as WT-DISC1. In order to test the significance of our in vitro data, we utilized in utero electroporation as an in vivo model to examine whether DISC1 variants regulated

the proliferation of neural progenitor cells. We performed unless in utero electroporation on embryonic day 13 (E13) brains and analyzed brains at E16, a time period when neurogenesis is peaking. We tested the ability of WT-DISC1 or the different DISC1 variants to rescue the decrease in neural progenitor proliferation after DISC1 knockdown, which we previously reported (Mao et al., 2009). We cotransfected neural progenitor cells with Venus-GFP to visualize cells and plasmids expressing control or DISC1 shRNA, together with WT-DISC1 or the different DISC1 variants. To measure proliferation of neural stem cells, we performed a 24 hr pulse label of 5-bromo-2-deoxyuridine (BrdU) at E15. Here, we found that expression of human WT-DISC1 was able to rescue the DISC1 shRNA-mediated decrease in the number of GFP/BrdU double-positive cells, indicating that WT-DISC1 can rescue the neural progenitor proliferation defect caused by DISC1 downregulation (Figure 3A). When comparing the different DISC1 variants against WT-DISC1, we found that the A83V, R264Q, and L607F variants could not rescue the number of double-positive GFP/BrdU cells similar to WT-DISC1, suggesting these variants are loss of function when compared with WT-DISC1 (Figure 3A).

In contrast, β-secretase processing of APP was concomitantly incr

In contrast, β-secretase processing of APP was concomitantly increased in ADAM10 prodomain mutant transgenic mice compared to in ADAM10-WT mice. ADAM10-DN transgenic mice exhibited even greater decreases and increases of α-secretase and β-secretase processing of APP, respectively, than did transgenic

mice expressing either ADAM10-Q170H or ADAM10-R181G, indicating that the prodomain mutations attenuated, but did not eliminate, α-secretase Epigenetic inhibitor activity. Next, the team investigated whether expression of the LOAD ADAM10 prodomain mutations could cause elevated cerebral amyloid deposition. For these experiments, they crossed the ADAM10-Q170H transgenic line, which had the highest APP-CTFβ level, with Tg2576 mice and aged the bigenic mice to 3, 12, and 20 months. Importantly, both endogenous soluble and Tg2576 transgenic soluble and insoluble Aβ40 and Aβ42 levels were dramatically higher in the brains of ADAM10-Q170H/Tg2576 bigenic mice than in those of the ADAM10-WT/Tg2576 mice, especially by 12 months of age. At 20 months of age, both amyloid plaque count and covered area were significantly increased in the brains of ADAM10-Q170H/Tg2576 mice relative to ADAM10-WT/Tg2576 see more mice. Interestingly, 20 month-old ADAM10-WT/Tg2576 mice were nearly devoid of amyloid plaques, whereas age-matched ADAM10-DN/Tg2576 mice displayed an enormous plaque

burden that was much greater than that in Tg2576 monogenic mice. These latter observations

provide proof of concept that increased α-secretase activity should be an efficacious therapeutic MycoClean Mycoplasma Removal Kit strategy for lowering cerebral Aβ accumulation in AD. In addition, aged ADAM10-Q170H/Tg2576 mice exhibited greater levels of microgliosis and astrogliosis than did ADAM10-WT/Tg2576 bigenic mice. Taken together, these results demonstrate that the ADAM10 prodomain mutations promote cerebral amyloid pathology via attenuated α-secretase processing of APP, thus providing a mechanism for the genetic association between LOAD and the ADAM10 Q170H and R181G mutations. Because previous studies suggested that sAPPα and ADAM10 play roles in neurogenesis, Tanzi and colleagues next investigated whether the ADAM10 prodomain mutations affect neurogenesis in the adult hippocampus. Interestingly, they found that proliferation of dentate gyrus neural precursor cells (NPCs) was significantly greater in 4-month-old ADAM10-WT transgenic mice than in nontransgenic mice. In contrast, NPC proliferation in ADAM10-Q170H, ADAM10-R181G, and ADAM10-DN mice was similar to that observed in nontransgenic mice. Importantly, the dentate gyrus in ADAM10-WT transgenic mice also displayed ∼50% more BrdU:NeuN double-positive neurons than did the dentate gyrus in nontransgenic mice, whereas the dentate gyrus in ADAM10-Q170H mice exhibited a smaller neuronal increase.

NM neurons that receive

a large number of small inputs ha

NM neurons that receive

a large number of small inputs had higher AIS Na+ channel densities, improving AP precision, whereas NM neurons that receive a smaller number of large inputs had lower AIS Na+ channel densites. Voltage-gated K+ channels in the AIS also play an important role in regulation PLX4032 clinical trial AP firing. In pyramidal neurons Kv1 channels, generating D-type current, have been shown to delay the onset of AP firing in response to sustained depolarisation (Storm, 1988), as well as influence AP threshold and interspike interval (Bekkers and Delaney, 2001 and Goldberg et al., 2008), whereas Kv7 channels influence spike-frequency adaptation, subthreshold resonance, and both spontaneous and AP burst firing (Hu et al., 2007, Peters et al., 2005, Shah et al., 2008 and Yue

and Yaari, 2004). Kv1 channels are the main K+ channel involved in regulating AP half-width in the AIS and the axon proper (Figure 4A) (Kole et al., 2007 and Shu et al., 2007b). With increasing distance from the soma the axonal AP half-width decreases steeply in parallel with an increase in the afterhyperpolarization (Kole et al., 2007). As a result, in cortical pyramidal neurons the AP half-width is ∼250 μs at the distal end of the AIS, similar to that of APs recorded in axonal boutons (Alle and Geiger, 2006 and Alle aminophylline et al., 2009). Keeping the AP in the AIS brief is likely to be crucial for enabling selleck screening library rapid recovery of Na+ channels from inactivation, consistent with the absence of AP failures in the AIS even at high frequencies (Popovic et al., 2011). More recent work indicates that calcium influx through AIS voltage-gated Ca2+ channels (Figure 4B) can activate calcium-activated K+ channels in the AIS of pyramidal neurons in ferret prefrontal cortex (Figure 4C) (Yu et al., 2010), providing an additional means to regulate axonal AP repolarization. Whether this observation can be extended to the AIS of other neuronal cell types remains to be tested. Together, these

data indicate that K+ channels in the AIS play a critical role in regulating axonal AP width and thereby the AP firing pattern in response to synaptic input. Recent observations also indicate that ion channels in the AIS can be modulated by neurotransmitters, thereby influencing AP firing patterns. This has been investigated in glycinergic brain stem interneurons, called cartwheel cells, where T-type Ca2+ channels in the AIS are selectively inhibited by dopamine, via a protein kinase C pathway (Figures 5A and 5B) (Bender et al., 2010). As a result the mode of spontaneous AP firing is converted from high-frequency bursts to tonic firing (Figures 5C and 5D) (Bender et al., 2012).

There are rare accounts of ganglion cells being confined to retin

There are rare accounts of ganglion cells being confined to retinal segments. For example, somatostatin-positive alpha cells in cat and rabbit retina are largely restricted to inferior retina (Sagar, 1987; White and Chalupa, 1991) and in the mouse, a subset of RGCs selective for upward motion occurs CH5424802 in dorsal retina (Kay et al., 2011). Because our approach is a functional characterization at the voxel level, retinotopic variations need not necessarily reflect regional variations in the distribution of different morphological classes of RGC. For example, there may be regional differences in the circuits driving RGC activity within the retina. Such differences, which

have been reported in the distributions of neurotransmitter and neuromodulator systems with various classes of retinal neurons (Wilson et al., 2011), could influence the function of a cell in a given morphological class. Presynaptic calcium levels may also be modulated by inputs onto RGC terminals within the tectum itself (Edwards and Cline, 1999). An obvious question is whether find more the functional retinotopic biases in RGC input is reflected in the postsynaptic tectal neurons. The rostro-caudal dendritic

extent for at least three tectal cell types is well below the size of the RGC functional domains that we have identified (Robles et al., 2011). Such spatially restricted sampling of RGCs by tectal neurons suggests that the regional biases in direction and orientation selectivity could L-NAME HCl be preserved in the population of postsynaptic tectal neurons. Indeed, a previous functional imaging study has suggested that retinotopic biases in direction-selective responses do indeed exist in the population of tectal cells

in the zebrafish tectum (Niell and Smith, 2005). While the underlying reasons for it are unknown, the functional architecture we have described may reflect an evolutionary solution that minimizes wiring costs associated with integrating and processing visual stimuli that are perhaps ethologically related (Chklovskii and Koulakov, 2004). Our description of the diversity and organization of inputs to the tectum will also provide a platform for studying emergence in tectal circuits. The property of emergence in neural networks, whereby a neuron produces an output that is not explicitly present in any of its individual inputs, is not well understood. The principal reason is that while the output of individual cells is simple to quantify, determining information about the input that may arise from tens to hundreds of cells is incredibly difficult. Indeed, recent attempts in the retina (Briggman et al., 2011) and visual cortex (Bock et al., 2011) using serial reconstruction at the nanoscale resolution are revealing the size of the challenge. Both of these studies are searching for rules of connectivity that explain the emergent functional properties of neurons.

This immunostaining showed that the vast majority of B5-I neurons

This immunostaining showed that the vast majority of B5-I neurons (∼90%) coexpressed the somatostatin receptor sst2A (Figures 1A and S1A available online). Furthermore, when we recorded from spinal interneurons genetically

labeled with the Bhlhb5-cre allele ( Ross et al., 2010), half showed strong hyperpolarization in response to somatostatin ( Figure 1B), confirming that B5-I neurons express functional KPT-330 concentration sst2A receptors. Given the loss of B5-I neurons in Bhlhb5−/− mice, we reasoned that there would be a corresponding decrease in the number of sst2A-expressing neurons in these animals. As predicted, the number of sst2A-expressing neurons was reduced by two-thirds in Bhlhb5−/− mice, with no significant change in the number of sst2A-negative inhibitory neurons ( Figures 1C and 1D). Thus, the vast majority of B5-I neurons belong to the subset of inhibitory spinal interneurons that express sst2A, and a large proportion of the sst2A-expressing population is missing in Bhlhb5−/− mice. Since somatostatin inhibits

neuronal activity and sst2A is the only somatostatin receptor that is expressed by dorsal horn neurons (see http://www.brain-map.org), the finding that B5-I neurons express sst2A allowed us to directly test the FG-4592 purchase idea that B5-I neurons normally function to inhibit itch. This experiment was important because, although we had previously shown that loss of B5-I neurons during development is associated with abnormally elevated itch (Ross et al., 2010), the evidence was merely correlative. Specifically, it was not clear whether B5-I neurons function in the adult to inhibit itch, or whether B5-I neurons play a key developmental role in the formation of proper itch circuits. We hypothesized that if B5-I neurons normally function to inhibit itch, then acute inhibition of these neurons by somatostatin would increase itch sensitivity (Figure 1E). Indeed, upon intrathecal injection of the somatostatin analog octreotide, we observed vigorous scratching, biting, and licking behavior that was suggestive of itch (Figure 1F),

consistent with previous reports (Seybold et al., 1982). This spontaneous behavior was dose dependent, with an immediate onset and a duration of approximately half an hour. Because B5-I neurons account for Florfenicol the majority (two-thirds) of sst2A-expressing cells, the finding that acute treatment with octreotide results in elevated scratching behavior is consistent with the hypothesis that B5-I neurons inhibit itch. Nevertheless, it remained possible that the observed scratching behavior was due instead to the effect of octreotide on the one-third of sst2A-expressing neurons that are not B5-I neurons. We therefore tested the effect of octreotide on Bhlhb5−/− mice, which lack B5-I neurons. Specifically, we reasoned that, if octreotide-induced scratching is due to inhibition of B5-I neurons, this treatment would have no effect in mice that lack these cells.