LncRNA TubAR complexes with TUBB4A and TUBA1A to promote microtubule assembly and maintain myelination

A long-standing hypothesis proposes that certain RNA(s) must exhibit structural roles in microtubule assembly. Here, we identify a long noncoding RNA (TubAR) that is highly expressed in cerebellum and forms RNA-protein complex with TUBB4A and TUBA1A, two tubulins clinically linked to cerebellar and myelination defects. TubAR knockdown in mouse cerebellum causes loss of oligodendrocytes and Purkinje cells, demyelination, and decreased locomotor activity. Biochemically, we establish the roles of TubAR in promoting TUBB4A-TUBA1A heterodimer formation and microtubule assembly. Intriguingly, different from the hypomyelination-causing mutations, the non-hypomyelination-causing mutation TUBB4A-R2G confers gain-of-function for an RNA-independent interaction with TUBA1A. Experimental use of R2G/A mutations restores TUBB4A-TUBA1A heterodimer formation, and rescues the neuronal cell death phenotype caused by TubAR knockdown. Together, we uncover TubAR as the long-elusive structural RNA for microtubule assembly and demonstrate how TubAR mediates microtubule assembly specifically from αβ-tubulin heterodimers, which is crucial for maintenance of cerebellar myelination and activity.

Visual cortex repetitive transcranial magnetic stimulation (rTMS) reversing neurodevelopmental impairments in adolescents with major psychiatric disorders (MPDs): A cross-species translational study

AIMS

Neurodevelopmental impairments are closely linked to the basis of adolescent major psychiatric disorders (MPDs). The visual cortex can regulate neuroplasticity throughout the brain during critical periods of neurodevelopment, which may provide a promising target for neuromodulation therapy. This cross-species translational study examined the effects of visual cortex repetitive transcranial magnetic stimulation (rTMS) on neurodevelopmental impairments in MPDs.

METHODS

Visual cortex rTMS was performed in both adolescent methylazoxymethanol acetate (MAM) rats and patients with MPDs. Functional magnetic resonance imaging (fMRI) and brain tissue proteomic data in rats and fMRI and clinical symptom data in patients were analyzed.

RESULTS

The regional homogeneity (ReHo) analysis of fMRI data revealed an increase in the frontal cortex and a decrease in the posterior cortex in the MAM rats, representing the abnormal neurodevelopmental pattern in MPDs. In regard to the effects of rTMS, similar neuroimaging changes, particularly reduced frontal ReHo, were found both in MAM rats and adolescent patients, suggesting that rTMS may reverse the abnormal neurodevelopmental pattern. Proteomic analysis revealed that rTMS modulated frontal synapse-associated proteins, which may be the underpinnings of rTMS efficacy. Furthermore, a positive relationship was observed between frontal ReHo and clinical symptoms after rTMS in patients.

CONCLUSION

Visual cortex rTMS was proven to be an effective treatment for adolescent MPDs, and the underlying neural and molecular mechanisms were uncovered. Our study provides translational evidence for therapeutics targeting the neurodevelopmental factor in MPDs.

Aberrant Hippocampal Development in Early-onset Mental Disorders and Promising Interventions: Evidence from a Translational Study

Early-onset mental disorders are associated with disrupted neurodevelopmental processes during adolescence. The methylazoxymethanol acetate (MAM) animal model, in which disruption in neurodevelopmental processes is induced, mimics the abnormal neurodevelopment associated with early-onset mental disorders from an etiological perspective. We conducted longitudinal structural magnetic resonance imaging (MRI) scans during childhood, adolescence, and adulthood in MAM rats to identify specific brain regions and critical windows for intervention. Then, the effect of repetitive transcranial magnetic stimulation (rTMS) intervention on the target brain region during the critical window was investigated. In addition, the efficacy of this intervention paradigm was tested in a group of adolescent patients with early-onset mental disorders (diagnosed with major depressive disorder or bipolar disorder) to evaluate its clinical translational potential. The results demonstrated that, compared to the control group, the MAM rats exhibited significantly lower striatal volume from childhood to adulthood (all P <0.001). In contrast, the volume of the hippocampus did not show significant differences during childhood (P >0.05) but was significantly lower than the control group from adolescence to adulthood (both P <0.001). Subsequently, rTMS was applied to the occipital cortex, which is anatomically connected to the hippocampus, in the MAM models during adolescence. The MAM-rTMS group showed a significant increase in hippocampal volume compared to the MAM-sham group (P <0.01), while the volume of the striatum remained unchanged (P >0.05). In the clinical trial, adolescents with early-onset mental disorders showed a significant increase in hippocampal volume after rTMS treatment compared to baseline (P <0.01), and these volumetric changes were associated with improvement in depressive symptoms (r = - 0.524, P = 0.018). These findings highlight the potential of targeting aberrant hippocampal development during adolescence as a viable intervention for early-onset mental disorders with neurodevelopmental etiology as well as the promise of rTMS as a therapeutic approach for mitigating aberrant neurodevelopmental processes and alleviating clinical symptoms.

Functional MRI of murine olfactory bulbs at 15.2T reveals characteristic activation patters when stimulated by different odors

Thanks to its increased sensitivity, single-shot ultrahigh field functional MRI (UHF fMRI) could lead to valuable insight about subtle brain functions such as olfaction. However, UHF fMRI experiments targeting small organs next to air voids, such as the olfactory bulb, are severely affected by field inhomogeneity problems. Spatiotemporal Encoding (SPEN) is an emerging single-shot MRI technique that could provide a route for bypassing these complications. This is here explored with single-shot fMRI studies on the olfactory bulbs of male and female mice performed at 15.2T. SPEN images collected on these organs at a 108 µm in-plane resolution yielded remarkably large and well-defined responses to olfactory cues. Under suitable T2* weightings these activation-driven changes exceeded 5% of the overall signal intensity, becoming clearly visible in the images without statistical treatment. The nature of the SPEN signal intensity changes in such experiments was unambiguously linked to olfaction, via single-nostril experiments. These experiments highlighted specific activation regions in the external plexiform region and in glomeruli in the lateral part of the bulb, when stimulated by aversive or appetitive odors, respectively. These strong signal activations were non-linear with concentration, and shed light on how chemosensory signals reaching the olfactory epithelium react in response to different cues. Second-level analyses highlighted clear differences among the appetitive, aversive and neutral odor maps; no such differences were evident upon comparing male against female olfactory activation regions.

Investigations of brain-wide functional and structural networks of dopaminergic and CamKIIα-positive neurons in VTA with DREADD-fMRI and neurotropic virus tracing technologies

BACKGROUND

The ventral tegmental area (VTA) contains heterogeneous cell populations. The dopaminergic neurons in VTA play a central role in reward and cognition, while CamKIIα-positive neurons, composed mainly of glutamatergic and some dopaminergic neurons, participate in the reward learning and locomotor activity behaviors. The differences in brain-wide functional and structural networks between these two neuronal subtypes were comparatively elucidated.

METHODS

In this study, we applied a method combining Designer Receptors Exclusively Activated by Designer Drugs (DREADD) and fMRI to assess the cell type-specific modulation of whole-brain neural networks. rAAV encoding the cre-dependent hM3D was injected into the right VTA of DAT-cre or CamKIIα-cre transgenic rats. The global brain activities elicited by DREADD stimulation were then detected using BOLD-fMRI. Furthermore, the cre-dependent antegrade transsynaptic viral tracer H129ΔTK-TT was applied to label the outputs of VTA neurons.

RESULTS

We found that DREADD stimulation of dopaminergic neurons induced significant BOLD signal changes in the VTA and several VTA-related regions including mPFC, Cg and Septum. More regions responded to selective activation of VTA CamKIIα-positive neurons, resulting in increased BOLD signals in VTA, Insula, mPFC, MC_R (Right), Cg, Septum, Hipp, TH_R, PtA_R, and ViC_R. Along with DREADD-BOLD analysis, further neuronal tracing identified multiple cortical (MC, mPFC) and subcortical (Hipp, TH) brain regions that are structurally and functionally connected by VTA dopaminergic and CamKIIα-positive neurons.

CONCLUSIONS

Our study dissects brain-wide structural and functional networks of two neuronal subtypes in VTA and advances our understanding of VTA functions.

Acute psilocybin increased cortical activities in rats

Psilocybin, a naturally occurring hallucinogenic component of magic mushrooms, has significant psychoactive effects in both humans and rodents. But the underlying mechanisms are not fully understood. Blood-oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is a useful tool in many preclinical and clinical trials to investigate psilocybin-induced changes of brain activity and functional connectivity (FC) due to its noninvasive nature and widespread availability. However, fMRI effects of psilocybin on rats have not been carefully investigated. This study aimed to explore how psilocybin affects resting-state brain activity and FC, through a combination of BOLD fMRI and immunofluorescence (IF) of EGR1, an immediate early gene (IEG) closely related to depressive symptoms. Ten minutes after psilocybin hydrochloride injection (2.0 mg/kg, i.p.), positive brain activities were observed in the frontal, temporal, and parietal cortex (including the cingulate cortex and retrosplenial cortex), hippocampus, and striatum. And a region-of-interest (ROI) -wise FC analysis matrix suggested increased interconnectivity of several regions, such as the cingulate cortex, dorsal striatum, prelimbic, and limbic regions. Further seed-based analyses revealed increased FC of cingulate cortex within the cortical and striatal areas. Consistently, acute psilocybin increased the EGR1 level throughout the brain, indicating a consistent activation thought the cortical and striatal areas. In conclusion, the psilocybin-induced hyperactive state of rats is congruent to that of humans, and may be responsible for its pharmacological effects.

A versatile genetic-encoded reporter for magnetic resonance imaging

It has been a long-cherished wish in biomedicine research to have an imaging tool to visualize gene expression, with good spatiotemporal resolution, in rodent and primate animals noninvasively and longitudinally. To this purpose, we here present a novel genetic encoded magnetic resonance imaging reporter, i.e., GEM reporter, for noninvasive visualization of cell-specific gene expression. The GEM reporter was developed through codon modification of a bacteria-originated manganese (Mn) binding protein, allowing the sequestration of endogenous Mn in local tissues. When expressed in bacteria, plant and animals, GEM reporter can robustly produce high image contrast in T1-weighted MRI without additional substrates or contrast agents. Importantly, GEM reporter can be tracked inherently by MRI in specific cells and tissues. These findings support GEM reporter as a versatile marker for deciphering gene expression spatiotemporally in living subjects.

The Value of Negative-Pressure Wound Therapy and Flap Surgery in Hidradenitis Suppurativa – A Single Center Analysis of Different Treatment Options

Background

Hidradenitis suppurativa is manifested by painful abscesses and scarring of sweat glands. Axillary, inguinal and genital regions are mostly affected. Multiple options exist in the treatment of hidradenitis suppurativa. The aim of this retrospective, mono-center cohort study was to analyze the outcome of different treatment methods after radical excision of hidradenitis suppurativa.

Methods

We retrospectively evaluated the treatment strategy and recurrence rate of hidradenitis suppurativa. We included all eligible patients of legal age between February 2003 and October 2021, with the diagnosis of Hidradenitis suppurativa and the necessity for surgical treatment. All patients with surgical treatment and direct wound closure by suture were excluded. Bacterial load and flora were analyzed for primary and secondary reconstruction in combination with negative-pressure wound therapy. Patient data were analyzed for recurrence rate and remission time according to different reconstructive techniques.

Results

In 44 affected anatomical sites (n = 23 patients) we treated 15 patients with negative-pressure wound therapy. Bacterial load and flora were lower in the last wound swab of patients with multi-surgical procedures (22 localizations) compared to the first wound swab independent of the use of negative-pressure wound therapy.

Wound closure, independent of a direct and multi-stage procedure was achieved by local fasciocutaneous flaps (n = 12), secondary intention healing (n = 7), secondary intention healing with buried chip skin grafts (n = 10), or split-thickness skin grafts (n = 15). Radical excision combined with split-thickness skin grafts showed the lowest recurrence rate in the follow-up (16%; n = 4).

Conclusion

Radical excision of hidradenitis suppurativa as gold standard for surgical treatment combined with negative-pressure wound therapy as multi-stage procedures ultimately reduced bacterial load and flora in our study. The use of split-thickness skin grafts showed the lowest recurrence rate.

A novel technology for in vivo detection of cell type-specific neural connection with AQP1-encoding rAAV2-retro vector and metal-free MRI

A mammalian brain contains numerous neurons with distinct cell types for complex neural circuits. Virus-based circuit tracing tools are powerful in tracking the interaction among the different brain regions. However, detecting brain-wide neural networks in vivo remains challenging since most viral tracing systems rely on postmortem optical imaging. We developed a novel approach that enables in vivo detection of brain-wide neural connections based on metal-free magnetic resonance imaging (MRI). The recombinant adeno-associated virus (rAAV) with retrograde ability, the rAAV2-retro, encoding the human water channel aquaporin 1 (AQP1) MRI reporter gene was generated to label neural connections. The mouse was micro-injected with the virus at the Caudate Putamen (CPU) region and subjected to detection with Diffusion-weighted MRI (DWI). The prominent structure of the CPU-connected network was clearly defined. In combination with a Cre-loxP system, rAAV2-retro expressing Cre-dependent AQP1 provides a CPU-connected network of specific type neurons. Here, we established a sensitive, metal-free MRI-based strategy for in vivo detection of cell type-specific neural connections in the whole brain, which could visualize the dynamic changes of neural networks in rodents and potentially in non-human primates.

In vivo imaging of astrocytes in the whole brain with engineered AAVs and diffusion-weighted magnetic resonance imaging

Astrocytes constitute a major part of the central nervous system and the delineation of their activity patterns is conducive to a better understanding of brain network dynamics. This study aimed to develop a magnetic resonance imaging (MRI)-based method in order to monitor the brain-wide or region-specific astrocytes in live animals. Adeno-associated virus (AAVs) vectors carrying the human glial fibrillary acidic protein (GFAP) promoter driving the EGFP-AQP1 (Aquaporin-1, an MRI reporter) fusion gene were employed. The following steps were included: constructing recombinant AAV vectors for astrocyte-specific expression, detecting MRI reporters in cell culture, brain regions, or whole brain following cell transduction, stereotactic injection, or tail vein injection. The astrocytes were detected by both fluorescent imaging and Diffusion-weighted MRI. The novel AAV mutation (Site-directed mutagenesis of surface-exposed tyrosine (Y) residues on the AAV5 capsid) significantly increased fluorescence intensity (p < 0.01) compared with the AAV5 wild type. Transduction of the rAAV2/5 carrying AQP1 induced the titer-dependent changes in MRI contrast in cell cultures (p < 0.05) and caudate-putamen (CPu) in the brain (p < 0.05). Furthermore, the MRI revealed a good brain-wide alignment between AQP1 levels and ADC signals, which increased over time in most of the transduced brain regions. In addition, the rAAV2/PHP.eB serotype efficiently introduced AOP1 expression in the whole brain via tail vein injection. This study provides an MRI-based approach to detect dynamic changes in astrocytes in live animals. The novel in vivo tool could help us to understand the complexity of neuronal and glial networks in different pathophysiological conditions.

Long-term follow-up of dynamic brain changes in patients recovered from COVID-19 without neurological manifestations

BACKGROUND

After the initial surge in COVID-19 cases, large numbers of patients were discharged from a hospital without assessment of recovery. Now, an increasing number of patients report postacute neurological sequelae, known as “long COVID” — even those without specific neurological manifestations in the acute phase.

METHODS

Dynamic brain changes are crucial for a better understanding and early prevention of “long COVID.” Here, we explored the cross-sectional and longitudinal consequences of COVID-19 on the brain in 34 discharged patients without neurological manifestations. Gray matter morphology, cerebral blood flow (CBF), and volumes of white matter tracts were investigated using advanced magnetic resonance imaging techniques to explore dynamic brain changes from 3 to 10 months after discharge.

RESULTS

Overall, the differences of cortical thickness were dynamic and finally returned to the baseline. For cortical CBF, hypoperfusion in severe cases observed at 3 months tended to recover at 10 months. Subcortical nuclei and white matter differences between groups and within subjects showed various trends, including recoverable and long-term unrecovered differences. After a 10-month recovery period, a reduced volume of nuclei in severe cases was still more extensive and profound than that in mild cases.

CONCLUSION

Our study provides objective neuroimaging evidence for the coexistence of recoverable and long-term unrecovered changes in 10-month effects of COVID-19 on the brain. The remaining potential abnormalities still deserve public attention, which is critically important for a better understanding of “long COVID” and early clinical guidance toward complete recovery.

FUNDING

National Natural Science Foundation of China.

Verification of pain-related neuromodulation mechanisms of icariin in knee osteoarthritis

Knee osteoarthritis (KOA) is a common disease with no specific treatment. Icariin (ICA) is considered an agent for KOA. This study aimed to confirm the pain-related neuromodulation mechanisms of ICA on KOA. Three experiments were designed: (1) verifying the therapeutic effects of ICA in vivo and in vitro, (2) exploring the potential pain-related neuromodulation pathways involved in ICA treatment by functional magnetic resonance imaging (fMRI) and virus retrograde tracing (VRT) and (3) confirming the pain-related targets by tandem mass tag (TMT)-based quantitative proteomics and bioinformatic analyses. Experiment 1 verified the efficacy of ICA in OA animal and cell models. Experiment 2 found a series of brain regions associated with KOA reversed by ICA treatment, indicating that a pain-related hypothalamic-mediated neuromodulation pathway and an endocannabinoid (EC)-related pathway contribute to ICA mechanisms. Experiment 3 explored and confirmed four pain-related genes involved in KOA and ICA treatment. We confirmed the key role of pain-related neuromodulation mechanisms in ICA treatment associated with its analgesic effect. Our findings contribute to considering ICA as a novel therapy for KOA.

Longitudinal neural connection detection using a ferritin-encoding adeno-associated virus vector and in vivo MRI method

The investigation of neural circuits is important for interpreting both healthy brain function and psychiatric disorders. Currently, the architecture of neural circuits is always investigated with fluorescent protein encoding neurotropic virus and ex vivo fluorescent imaging technology. However, it is difficult to obtain a whole‐brain neural circuit connection in living animals, due to the limited fluorescent imaging depth. Herein, the noninvasive, whole‐brain imaging technique of MRI and the hypotoxicity virus vector AAV (adeno‐associated virus) were combined to investigate the whole‐brain neural circuits in vivo. AAV2‐retro are an artificially‐evolved virus vector that permits access to the terminal of neurons and retrograde transport to their cell bodies. By expressing the ferritin protein which could accumulate iron ions and influence the MRI contrast, the neurotropic virus can cause MRI signal changes in the infected regions. For mice injected with the ferritin‐encoding virus vector (rAAV2‐retro‐CAG‐Ferritin) in the caudate putamen (CPu), several regions showed significant changes in MRI contrasts, such as PFC (prefrontal cortex), HIP (hippocampus), Ins (insular cortex) and BLA (basolateral amygdala). The expression of ferritin in those regions was also verified with ex vivo fluorescence imaging. In addition, we demonstrated that changes in T2 relaxation time could be used to identify the spread area of the virus in the brain over time. Thus, the neural connections could be longitudinally detected with the in vivo MRI method. This novel technique could be utilized to observe the viral infection process and detect the neural circuits in a living animal.

CNN-based qualitative detection of bone mineral density via diagnostic CT slices for osteoporosis screening

The features extracted from diagnostic computed tomography (CT) slices were used to qualitatively detect bone mineral density (BMD) through neural network models, and the evaluation results indicated that it may be a promising approach to perform osteoporosis screening in clinical practice.

INTRODUCTION

The purpose of this study is to design a novelty diagnostic method for osteoporosis screening by using the convolutional neural network (CNN), which can be incorporated into the procedure of routine CT diagnostic in medical examination thereby improving the osteoporosis diagnosis and reducing the patient burden.

METHODS

The proposed CNN-based method mainly comprises two functional modules to perform qualitative detection of BMD by analyzing the diagnostic 2D CT slice. The first functional module aims to locate and segment the ROI of diagnostic 2D CT slice, called Mark-Segmentation-Network (MS-Net). The second functional module is used to determine the category of BMD by the features of ROI, called BMD-Classification-Network (BMDC-Net). The diagnostic 2D CT slice of pedicle level in lumbar vertebrae (L1) was selected from 3D CT image in our experiments firstly. Then, the trained MS-Net can get the mark image of input original 2D CT slice, thereby obtain the segmentation image. Finally, the trained BMDC-Net can obtain the probability value of normal bone mass, low bone mass, and osteoporosis by inputting the segmentation image. On the basis of network results, the radiologists can provide preliminary qualitative diagnosis results of BMD.

RESULTS

Training of the network was performed on diagnostic 2D CT slices of 150 patients. The network was tested on 63 patients. Each patient corresponds to a 2D CT slice. The proposed MS-Net has an excellent segmentation precision on the shape preservation of different lumbar vertebra. The dice index (DI), pixel accuracy (PA), and intersection over union (IOU) of segmentation results are greater than 0.8. The proposed BMDC-Net achieved an accuracy of 76.65% and an area under the receiver operating characteristic curve of 0.9167.

CONCLUSIONS

This study proposed a novel method for qualitative detection of BMD via diagnostic CT slices and it has great potential in clinical applications for osteoporosis screening. The method can potentially reduce the manual burden to radiologists and diagnostic cost to patients.

Long-term microstructure and cerebral blood flow changes in patients recovered from COVID-19 without neurological manifestations

BACKGROUNDThe coronavirus disease 2019 (COVID-19) rapidly progressed to a global pandemic. Although some patients totally recover from COVID-19 pneumonia, the disease's long-term effects on the brain still need to be explored.METHODSWe recruited 51 patients with 2 subtypes of COVID-19 (19 mild and 32 severe) with no specific neurological manifestations at the acute stage and no obvious lesions on the conventional MRI 3 months after discharge. Changes in gray matter morphometry, cerebral blood flow (CBF), and white matter (WM) microstructure were investigated using MRI. The relationship between brain imaging measurements and inflammation markers was further analyzed.RESULTSCompared with healthy controls, the decrease in cortical thickness/CBF and the changes in WM microstructure were more severe in patients with severe disease than in those with mild disease, especially in the frontal and limbic systems. Furthermore, changes in brain microstructure, CBF, and tract parameters were significantly correlated (P < 0.05) with the inflammatory markers C-reactive protein, procalcitonin, and interleukin 6.CONCLUSIONIndirect injury related to inflammatory storm may damage the brain, altering cerebral volume, CBF, and WM tracts. COVID-19-related hypoxemia and dysfunction of vascular endothelium may also contribute to neurological changes. The abnormalities in these brain areas need to be monitored during recovery, which could help clinicians understand the potential neurological sequelae of COVID-19.FUNDINGNatural Science Foundation of China.

A new GABAergic somatostatin projection from the BNST onto accumbal parvalbumin neurons controls anxiety

The prevailing view is that parvalbumin (PV) interneurons play modulatory roles in emotional response through local medium spiny projection neurons (MSNs). Here, we show that PV activity within the nucleus accumbens shell (sNAc) is required for producing anxiety-like avoidance when mice are under anxiogenic situations. Firing rates of sNAc^PV neurons were negatively correlated to exploration time in open arms (threatening environment). In addition, sNAc^PV neurons exhibited high excitability in a chronic stress mouse model, which generated excessive maladaptive avoidance behavior in an anxiogenic context. We also discovered a novel GABAergic pathway from the anterior dorsal bed nuclei of stria terminalis (adBNST) to sNAc^PV neurons. Optogenetic activation of these afferent terminals in sNAc produced an anxiolytic effect via GABA transmission. Next, we further demonstrated that chronic stressors attenuated the inhibitory synaptic transmission at adBNST^GABA → sNAc^PV synapses, which in turn explains the hyperexcitability of sNAc PV neurons on stressed models. Therefore, activation of these GABAergic afferents in sNAc rescued the excessive avoidance behavior related to an anxious state. Finally, we identified that the majority GABAergic input neurons, which innervate sNAc^PV cells, were expressing somatostatin (SOM), and also revealed that coordination between SOM- and PV- cells functioning in the BNST → NAc circuit has an inhibitory influence on anxiety-like responses. Our findings provide a potentially neurobiological basis for therapeutic interventions in pathological anxiety.

Neuronal mechanisms of adenosine A2A receptors in the loss of consciousness induced by propofol general anesthesia with functional magnetic resonance imaging

Propofol is the most common intravenous anesthetic agent for induction and maintenance of anesthesia, and has been used clinically for more than 30 years. However, the mechanism by which propofol induces loss of consciousness (LOC) remains largely unknown. The adenosine A_2A receptor (A_2A R) has been extensively proven to have an effect on physiological sleep. It is, therefore, important to investigate the role of A_2A R in the induction of LOC using propofol. In the present study, the administration of the highly selective A_2A R agonist (CGS21680) and antagonist (SCH58261) was utilized to investigate the function of A_2A R under general anesthesia induced by propofol by means of animal behavior studies, resting-state magnetic resonance imaging and c-Fos immunofluorescence staining approaches. Our results show that CGS21680 significantly prolonged the duration of LOC induced by propofol, increased the c-Fos expression in nucleus accumbens (NAc) and suppressed the functional connectivity of NAc-dorsal raphe nucleus (DR) and NAc-cingulate cortex (CG). However, SCH58261 significantly shortened the duration of LOC induced by propofol, decreased the c-Fos expression in NAc, increased the c-Fos expression in DR, and elevated the functional connectivity of NAc-DR and NAc-CG. Collectively, our findings demonstrate the important roles played by A_2A R in the LOC induced by propofol and suggest that the neural circuit between NAc-DR maybe controlled by A_2A R in the mechanism of anesthesia induced by propofol.

Investigation of robust visual reaction and functional connectivity in the rat brain induced by rocuronium bromide with functional MRI

Functional magnetic resonance imaging (fMRI) has been used extensively to understand the brain function of a wide range of neurological and psychiatric disorders. When applied to animal studies, anesthesia is always used to reduce the movement of the animal and also reduce the impacts on the results of fMRI. Several awake models have been proposed by applying physical animal movement restrictions. However, restraining devices were designed for individual subject which limits the promotion of fMRI in awake animals. Here, a clinical muscle relaxant rocuronium bromide (RB) was introduced to restrain the animal in fMRI scanning time. The fMRI reactions of the animal induced with RB and the other two commonly used anesthesia protocols were investigated. The results of the fMRI showed that there were increased functional connectivity and well-round visual responses in the RB induced state. Furthermore, significant BOLD signal changes were found in the cortex and thalamus regions when the animal revived from isoflurane, which should be essential to further understand the effects of anesthesia on the brain.

Dynamic Changes of Functional Neuronal Activities Between the Auditory Pathway and Limbic Systems Contribute to Noise-Induced Tinnitus with a Normal Audiogram

Tinnitus is thought to be triggered by aberrant neural activity in the central auditory pathway and is often accompanied by comorbidities of emotional distress and anxiety, which imply maladaptive functional connectivity to limbic structures, such as the amygdala and hippocampus. Tinnitus patients with normal audiograms can also have accompanying anxiety and depression, clinically. To test the role of functional connectivity between the central auditory pathway and limbic structures in patients with tinnitus with normal audiograms, we developed a murine noise-induced tinnitus model with a temporary threshold shift (TTS). Tinnitus mice exhibited reduced auditory brainstem response wave I amplitude, and an enhanced wave IV amplitude and wave IV/I amplitude ratio, as compared with control and non-tinnitus mice. Resting-state functional magnetic resonance imaging (fMRI) was used to identify abnormal connectivity of the amygdala and hippocampus and to determine the relationship with tinnitus characteristics. We found increased fMRI responses with amplitude of low-frequency fluctuation (ALFF) in the auditory cortex and decreased ALFF in the amygdala and hippocampus at day 1, but decreased ALFF in the auditory cortex and increased ALFF in the amygdala at day 28 post-noise exposure in tinnitus mice. Decreased functional connectivity between auditory brain regions and limbic structures was demonstrated at day 28 in tinnitus mice. Therefore, aberrant neural activities in tinnitus mice with TTS involved not only the central auditory pathway, but also limbic structures, and there was maladaptive functional connectivity between the central auditory pathway and limbic structures, such as the amygdala and hippocampus.

Circular RNA Transcriptomic Analysis of Primary Human Brain Microvascular Endothelial Cells Infected with Meningitic Escherichia coli

With their essential regulatory roles in gene expression and high abundance in the brain, circular RNAs (circRNAs) have recently attracted considerable attention. Many studies have shown that circRNAs play important roles in the pathology of CNS diseases, but whether circRNAs participate in E. coli-induced bacterial meningitis is unclear. We used high-throughput sequencing to analyze the transcriptional profiles of host circRNAs in primary brain microvascular endothelial cells in response to meningitic E. coli. A total of 308 circRNAs were significantly altered, including 140 upregulated and 168 downregulated ones (p < 0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology enrichment of the parental genes of these altered circRNAs indicated that they are likely to be involved in diverse biological processes via influencing the expression of their parental genes. Coupled with our previous mRNA and microRNA sequencing data, a competing endogenous RNA analysis was performed, and the potential regulatory network was preliminarily constructed and validated. By revealing the transcriptional profiles of the host circRNAs involved in E. coli meningitis, it is envisaged that the novel insight gained into the regulatory mechanisms of circRNAs in the development of bacterial meningitis will lead to better understanding of how to prevent and treat bacterial CNS infections.

Induction of VEGFA and Snail-1 by meningitic Escherichia coli mediates disruption of the blood-brain barrier

Escherichia coli is the most common Gram-negative bacterium that possesses the ability to cause neonatal meningitis, which develops as circulating bacteria penetrate the blood-brain barrier (BBB). However, whether meningitic E. coli could induce disruption of the BBB and the underlying mechanisms are poorly understood. Our current work highlight for the first time the participation of VEGFA and Snail-1, as well as the potential mechanisms, in meningitic E. coli induced disruption of the BBB. Here, we characterized a meningitis-causing E. coli PCN033, and demonstrated that PCN033 invasion could increase the BBB permeability through downregulating and remodeling the tight junction proteins (TJ proteins). This process required the PCN033 infection-induced upregulation of VEGFA and Snail-1, which involves the activation of TLR2-MAPK-ERK1/2 signaling cascade. Moreover, production of proinflammatory cytokines and chemokines in response to infection also promoted the upregulation of VEGFA and Snail-1, therefore further mediating the BBB disruption. Our observations reported here directly support the involvement of VEGFA and Snail-1 in meningitic E. coli induced BBB disruption, and VEGFA and Snail-1 would therefore represent the essential host targets for future prevention of clinical E. coli meningitis.

Mesenchymal stem cells and myoblast differentiation under HGF and IGF-1 stimulation for 3D skeletal muscle tissue engineering

Background

Volumetric muscle loss caused by trauma or after tumour surgery exceeds the natural regeneration capacity of skeletal muscle. Hence, the future goal of tissue engineering (TE) is the replacement and repair of lost muscle tissue by newly generating skeletal muscle combining different cell sources, such as myoblasts and mesenchymal stem cells (MSCs), within a three-dimensional matrix. Latest research showed that seeding skeletal muscle cells on aligned constructs enhance the formation of myotubes as well as cell alignment and may provide a further step towards the clinical application of engineered skeletal muscle.

In this study the myogenic differentiation potential of MSCs upon co-cultivation with myoblasts and under stimulation with hepatocyte growth factor (HGF) and insulin-like growth factor-1 (IGF-1) was evaluated. We further analysed the behaviour of MSC-myoblast co-cultures in different 3D matrices.

Results

Primary rat myoblasts and rat MSCs were mono- and co-cultivated for 2, 7 or 14 days. The effect of different concentrations of HGF and IGF-1 alone, as well as in combination, on myogenic differentiation was analysed using microscopy, multicolour flow cytometry and real-time PCR. Furthermore, the influence of different three-dimensional culture models, such as fibrin, fibrin-collagen-I gels and parallel aligned electrospun poly-ε-caprolacton collagen-I nanofibers, on myogenic differentiation was analysed. MSCs could be successfully differentiated into the myogenic lineage both in mono- and in co-cultures independent of HGF and IGF-1 stimulation by expressing desmin, myocyte enhancer factor 2, myosin heavy chain 2 and alpha-sarcomeric actinin. An increased expression of different myogenic key markers could be observed under HGF and IGF-1 stimulation. Even though, stimulation with HGF/IGF-1 does not seem essential for sufficient myogenic differentiation. Three-dimensional cultivation in fibrin-collagen-I gels induced higher levels of myogenic differentiation compared with two-dimensional experiments. Cultivation on poly-ε-caprolacton-collagen-I nanofibers induced parallel alignment of cells and positive expression of desmin.

Conclusions

In this study, we were able to myogenically differentiate MSC upon mono- and co-cultivation with myoblasts. The addition of HGF/IGF-1 might not be essential for achieving successful myogenic differentiation. Furthermore, with the development of a biocompatible nanofiber scaffold we established the basis for further experiments aiming at the generation of functional muscle tissue.

Electronic supplementary material

The online version of this article (doi:10.1186/s12860-017-0131-2) contains supplementary material, which is available to authorized users.

A Pilot Metabolic Profiling Study of Patients With Neonatal Jaundice and Response to Phototherapy

Phototherapy has been widely used in treating neonatal jaundice, but detailed metabonomic profiles of neonatal jaundice patients and response to phototherapy have not been characterized. Our aim was to depict the serum metabolic characteristics of neonatal jaundice patients relative to controls and changes in response to phototherapy. A (1) H nuclear magnetic resonance (NMR)-based metabonomic approach was employed to study the metabolic profiling of serum from healthy infants (n = 25) and from infants with neonatal jaundice (n = 30) pre- and postphototherapy. The acquired data were processed by multivariate principal component analysis (PCA) and orthogonal partial least-squares-discriminant analysis (OPLS-DA). The PLS-DA and OPLS-DA model identified nine metabolites capable of distinguishing patients from controls. In addition, 28 metabolites such as β-glucose, α-glucose, valine, and pyruvate changed in response to phototherapy. This study offers useful information on metabolic disorders in neonatal jaundice patients and the effects of phototherapy on lipids, amino acid, and energy metabolism.

ZnRF3 induces apoptosis of gastric cancer cells by antagonizing Wnt and Hedgehog signaling

AIM

The aim of this paper was to investigate the function an importance of E3-ubiquitin ligase ZnRF3 in the progression of cancer cell growth.

METHODS

A total of 58 patients (44 males and 14 females) were enrolled in the study and their gastric tumors were removed surgically and were staged by the TNM approach. Among these patients, 43 patients died and 15 survived at the time of this study. The tumors and the paracancerous tissues were examined by immunohostochemistry for the expression of ZnRF3. We assessed the expression of ZnRF3 in gastric tumors and paracancerous tissues from our patients and related this to patient survival.

RESULTS

A large proportion of malignant cancers of the stomach are gastric adenocarcinoma type. In spite of many studies, the molecular basis for this cancer is still unclear. Deregulated cell proliferative signaling via Wnt/β-catenin and Hedgehog pathways is considered important in the pathogenesis of many cancers including the gastric cancer. Recent studies identified ZnRF3 protein, which is a E3-ubiquitin ligase and which is either deleted or mutated in cancers, to inhibit Wnt signaling. However, the significance of ZnRF3 in the control of gastric cancer and whether it also regulates Hedgehog signaling pathway, is not known. ZnRF3 expression was much higher in tumors from aged patients. Male patients showed higher mortality than the females. Mechanistic studies using normal gastric cells (GES1) and gastric cancer cells (MGC-803) infected with either AdZnRF3 or AdGFP viral vectors, revealed that ZnRF3 overexpression causes significantly more apoptosis and lowered proliferation of cancer cells. ZnRF3 overexpression led to greatly reduced levels of Lgr5, a component of Wnt signaling and also Gli1, a component of Hedgehog signaling. Thus, ZnRF3 negatively influences both the Wnt and Hedgehog proliferative pathways and probably this way it negatively regulates cancer progression. These results suggest the importance of normal ZnRF3 function in checking the progression of cancer cell growth and indicate that a lack of this protein can lead to poorer clinical outcomes for gastric cancer patients.

CONCLUSION

We observed a clear relationship between ZnRF3 expression in paracancerous tissue and tumor size.

Pituitary hormone gene expression and secretion in human growth hormone-releasing hormone transgenic mice: focus on lactotroph function

The human GH-releasing hormone (hGHRH) transgenic mouse has a hyperplastic anterior pituitary gland that eventually develops into an adenoma. We showed previously that the number of lactotrophs in the male hGHRH transgenic mouse is increased 2-fold, yet there is no concomitant increase in plasma levels of PRL. To further elucidate underlying changes in lactotroph function in the hGHRH transgenic mouse, the objectives of this study were to 1) examine the relative differences in PRL gene expression in transgenic mice and their siblings, 2) quantify PRL secretion at the level of the individual cell, 3) determine whether tyrosine hydroxylase gene expression and/or activity are altered in the hypothalamus of transgenic mice, and 4) assess dopamine receptor gene expression and functional sensitivity in lactotrophs of transgenic mice. Total PRL messenger RNA (mRNA) levels were increased nearly 5-fold in the hGHRH transgenic mouse, whereas the concentrations of PRL mRNA (PRL mRNA per microg total RNA) were unchanged. In contrast, total PRL contents were unchanged, whereas the concentrations of PRL (micrograms of PRL per mg total protein) were decreased 3-fold. Hypothalamic tyrosine hydroxylase steady state mRNA levels were not altered in the hGHRH transgenic mice, but hypothalamic tyrosine hydroxylase activity was increased 2-fold in transgenic mice. Dopamine D2 receptor mRNA concentrations in the anterior pituitary were increased 2.5-fold in hGHRH transgenic mice, and total pituitary D2 receptor mRNA levels were increased nearly 10-fold. Furthermore, the basal secretory capacity of lactotrophs from transgenic mice was increased significantly at the level of the single cell, and dopamine inhibited the secretion of PRL to a greater extent in hGHRH transgenic mice. Thus, although the total number of lactotrophs is increased 2-fold in hGHRH transgenic mice, the present data are consistent with the hypothesis that increased hypothalamic dopamine synthesis and release coupled with an increase in D2 dopamine receptor gene expression and functional sensitivity in the pituitary result in normal plasma levels of PRL.

Targeted overexpression of galanin in lactotrophs of transgenic mice induces hyperprolactinemia and pituitary hyperplasia

We generated transgenic mice that carry 4.6 kb of the mouse galanin gene fused to 2.5 kb of the rat PRL promoter. In all transgenic lines that carried and transmitted the transgene, there were significant increases in galanin messenger RNA and peptide levels in the anterior pituitary in both male and female transgenic mice, and the elevation of galanin was restricted to the anterior lobe. Furthermore, galanin release from pituitary cells in vitro of both male and female transgenic mice was dramatically increased compared with that in control mice. At 2-4 months of age, pituitary PRL contents in female transgenic mice were increased compared with those in normal controls. Moreover, PRL messenger RNA levels were increased in female transgenic mice. However, plasma levels of PRL in female transgenic mice were not significantly higher until 6 months of age. By 11 months of age, cell numbers in the anterior pituitary were increased in female, but not male, transgenic mice. The percentage of lactotrophs in female transgenic mice as well as PRL gene expression per cell were significantly higher. No differences were detected in PRL content, gene expression, or release between normal and transgenic male mice. Six weeks of estrogen treatment significantly increased anterior pituitary weights and PRL secretion in male transgenic mice compared with that in normal male mice. In addition, anterior pituitary weights and PRL secretion were decreased in female transgenic mice compared with controls 6 weeks after ovariectomy. We conclude that overexpression of galanin in lactotrophs stimulates PRL synthesis and secretion and acts as a growth factor resulting in the formation of pituitary hyperplasia and hyperprolactinemia. Furthermore, estrogen appears critical for these galanin-mediated events.

Hydrodynamic Interactions and Mean Settling Velocity of Porous Particles in a Dilute Suspension

A theoretical investigation is conducted to study hydrodynamic interactions among porous spheres under creeping flow conditions. The particles may differ in size and permeability. Based on the Brinkman equation governing the fluid flow inside the particle, the flow field, and the drag force and torque on the particle are calculated numerically using a boundary collocation method. The results show that the hydrodynamic interaction increases with decreasing permeability. An important feature is that unlike the singular force and torque for two touching identical impermeable spheres undergoing certain motions with planar symmetry, the force and torque always remain finite for the case of two porous spheres. Using the resulting hydrodynamic interactions, the average sedimentation velocity of porous spheres suspended in a bounded fluid is also evaluated to determine the leading order effect of the particle concentration. Because of weaker hydrodynamic interactions among porous spheres, the hindrance coefficient is smaller than that for impermeable particles. When the porous spheres carry charge, the hindrance effect is augmented by increasing the double layer thickness. Copyright 1999 Academic Press.

The human growth hormone-releasing hormone transgenic mouse as a model of modest obesity: differential changes in leptin receptor (OBR) gene expression in the anterior pituitary and hypothalamus after fasting and OBR localization in somatotrophs

We reported previously an increase in leptin receptor (OBR) gene expression in the anterior pituitary of human GH-releasing hormone (hGHRH) transgenic mice. The primary goal of this study was to investigate the possible mechanisms regulating OBR expression in these mice. Compared with normal sibling controls, hGHRH transgenic mice had significantly greater amounts of abdominal fat, higher levels of leptin messenger RNA (mRNA), and a 2-fold increase in plasma leptin concentrations. Despite normal plasma glucose levels, hGHRH transgenic mice had 4.5-fold elevated levels of plasma insulin. Using a ribonuclease protection assay, we measured the mRNA levels of the OBR long form (OBR(L)) in the anterior pituitary and hypothalamus after 48 h of fasting. In the anterior pituitary, food deprivation induced dramatic increases in OBR(L) mRNA levels in both normal and transgenic mice. In contrast, in the hypothalamus, fasting resulted in a significant decrease in OBR(L) gene expression in normal mice, and no changes were detected in hGHRH transgenic mice. Using dual in situ hybridization, OBR(L) mRNA was detected in somatotrophs. Moreover, the number of OBR(L)-positive pituitary cells as well as the percentage of OBR(L)-positive cells that express GH mRNA were increased in transgenic mice. In conclusion, 1) the modest obesity in hGHRH transgenic mice is associated with increases in leptin synthesis and secretion as well as insulin secretion; 2) GH and/or GHRH as well as leptin and insulin may differentially contribute to the changes in OBR(L) gene expression in the anterior pituitary and the hypothalamus; 3) the response of OBR(L) gene expression in the hypothalamus to fasting is absent in the modestly obese hGHRH transgenic mice; and 4) somatotrophs are target cells for leptin, and the increase in OBR(L) gene expression in the pituitary of hGHRH transgenic mice is due at least in part to the increase in the number of cells expressing OBR(L).

Quantitative assessment of mRNA cap analogues as inhibitors of in vitro translation

Fifty-eight analogues of the 5'-terminal 7-methylguanosine-containing cap of eukaryotic messenger RNA were synthesized and tested for their ability to inhibit in vitro protein synthesis. A new algorithm was developed for extracting KI, the dissociation constant for the cap analogue.eIF4E complex, from protein synthesis data. The results indicated that addition of a methyl group to the N2 of guanine produced more inhibitory compounds, but addition of a second methyl group to N2 decreased the level of inhibition dramatically. Aryl substitution at N7 improved the efficacy of guanine nucleoside monophosphate analogues. Substitution of the aromatic ring at the para position with methyl or NO2 groups abolished this effect, but substitution with Cl or F enhanced it. By contrast, aryl substitution at N7 in nucleoside di- or triphosphate analogues produced only minor effects, both positive and negative. By far the strongest determinants of inhibitory activity for cap analogues were phosphate residues. The beneficial effect of more phosphate residues was related more to anionic charge than to the number of phosphate groups per se. The second nucleotide residue in analogues of the form m7GpppN affected inhibitory activity in the order G > C > U > A, but there was no effect of 2'-O-modification. Opening the first ribose ring of m7GpppG analogues dramatically decreased activity, but alterations at the 2'-position of this ribose had no effect. Non-nucleotide-based cap analogues containing benzimidazole derivatives were inhibitory, though less so than those containing 7-methylguanine.

Galanin within the normal and hyperplastic anterior pituitary gland: localization, secretion, and functional analysis in normal and human growth hormone-releasing hormone transgenic mice

Studies evaluating estrogen-induced anterior pituitary tumors revealed a strong direct correlation between expression of the peptide galanin and tumor growth. To evaluate further the potential roles of galanin in the hyperplastic pituitary, we used a model of estrogen-independent anterior pituitary tumor formation, the male human GH-releasing hormone (hGHRH) transgenic mouse. Pituitaries of hGHRH transgenic mice are characterized by a hyperplasia of somatotrophs and contain markedly elevated levels of galanin. We examined the population of galanin-producing pituitary cells in 4- to 6-month-old male hGHRH transgenic mice and their nontransgenic siblings. The percentage of galanin-containing pituitary cells was significantly increased within the anterior pituitaries of hGHRH transgenic mice. By using the cell immunoblot assay we found that the basal secretion of galanin and GH from individual pituitary cells of hGHRH transgenic mice was significantly greater than that from pituitary cells of nontransgenic mice. By modifying the cell immunoblot assay, we determined that somatotrophs from both hGHRH transgenic and normal mice that were positive for galanin immunoreactivity secreted significantly greater amounts of GH than those somatotrophs devoid of galanin immunoreactivity. Moreover, immunoneutralization of galanin significantly decreased GH secretion from pituitary cells obtained from hGHRH transgenic mice. Thus, we now show that the increased levels of galanin peptide within the hyperplastic pituitaries of hGHRH transgenic mice are due to an increase in the population of cells containing galanin, and that galanin participates in the augmented secretion of GH from hyperplastic proliferating pituitary cells.

Cleavage of Poly(A)-binding protein by coxsackievirus 2A protease in vitro and in vivo: another mechanism for host protein synthesis shutoff?

Infection of cells by picornaviruses of the rhinovirus, aphthovirus, and enterovirus groups results in the shutoff of host protein synthesis but allows viral protein synthesis to proceed. Although considerable evidence suggests that this shutoff is mediated by the cleavage of eukaryotic translation initiation factor eIF4G by sequence-specific viral proteases (2A protease in the case of coxsackievirus), several experimental observations are at variance with this view. Thus, the cleavage of other cellular proteins could contribute to the shutoff of host protein synthesis and stimulation of viral protein synthesis. Recent evidence indicates that the highly conserved 70-kDa cytoplasmic poly(A)-binding protein (PABP) participates directly in translation initiation. We have now found that PABP is also proteolytically cleaved during coxsackievirus infection of HeLa cells. The cleavage of PABP correlated better over time with the host translational shutoff and onset of viral protein synthesis than did the cleavage of eIF4G. In vitro experiments with purified rabbit PABP and recombinant human PABP as well as in vivo experiments with Xenopus oocytes and recombinant Xenopus PABP demonstrate that the cleavage is catalyzed by 2A protease directly. N- and C-terminal sequencing indicates that cleavage occurs uniquely in human PABP at 482VANTSTQTM downward arrowGPRPAAAAAA500, separating the four N-terminal RNA recognition motifs (80%) from the C-terminal homodimerization domain (20%). The N-terminal cleavage product of PABP is less efficient than full-length PABP in restoring translation to a PABP-dependent rabbit reticulocyte lysate translation system. These results suggest that the cleavage of PABP may be another mechanism by which picornaviruses alter the rate and spectrum of protein synthesis.

Galanin in normal and hyperplastic anterior pituitary cells. From pituitary tumor cell lines to transgenic mice

Studies on the regulation of galanin expression in the epithelial cells of the anterior pituitary gland have provided a wealth of insight into the cellular and molecular biology of this unique peptide. Galanin is localized within subpopulations of specific pituitary cell types, and hypothalamic as well as gonadal factors including dopamine, somatostatin, thyrotropin-releasing hormone, growth hormone-releasing hormone (GHRH), estrogen, and progesterone dynamically regulate its expression and release. Galanin gene expression and peptide secretion are markedly increased in estrogen-induced prolactinomas, wherein galanin serves as both an autocrine and paracrine hormone regulating prolactin secretion. Galanin mRNA and peptide levels are also dramatically elevated in somatotroph adenomas of human GHRH transgenic mice. Moreover, galanin secretion is increased from the hyperplastic somatotrophs of hGHRH transgenic mice. However, not all pituitary adenomas are associated with increased galanin gene expression; galanin synthesis is repressed in 131I-induced thyrotroph adenomas. Thus, galanin acts locally to regulate pituitary hormone secretion and appears to act as a mitogenic factor to increase the proliferation of pituitary cells in a cell-type specific manner.

Function of galanin in the anterior pituitary of estrogen-treated Fischer 344 rats: autocrine and paracrine regulation of prolactin secretion

Estrogen is a robust stimulator of galanin synthesis and secretion in the anterior pituitary. Galanin is colocalized in lactotrophs in the estrogen-treated anterior pituitary, and its roles in lactotroph function are still being elucidated. In the present studies, we quantified the phenotypes of estrogen-treated Fischer 344 rat anterior pituitary cells expressing the galanin gene by dual in situ hybridization. The total population of galanin-positive pituitary cells increased from undetectable levels to 16% of all cells after 2 weeks of estrogen treatment. More than 90% of the galanin-positive cells coexpressed PRL messenger RNA, and one-third of the lactotrophs expressed galanin messenger RNA. We hypothesized that galanin in the anterior pituitary may contribute to the heterogeneous secretion of PRL, and that one of the functions of galanin is to regulate PRL secretion in an autocrine/paracrine manner. To test this hypothesis, we performed the reverse hemolytic plaque assay combined with in situ hybridization to measure PRL secretion and galanin gene expression within the same individual cells. PRL secretion from galanin-positive lactotrophs was significantly greater than that from galanin-negative lactotrophs. Moreover, treatment with galanin antiserum significantly attenuated PRL secretion from galanin-positive cells, and treatment with galanin significantly enhanced PRL secretion from galanin-negative lactotrophs. In conclusion, these data provide direct evidence that galanin derived from the estrogen-treated anterior pituitary stimulates PRL secretion in both autocrine and paracrine manners.