Probes for INS

Stress contributes to numerous psychiatric disorders. CRF signaling and CRF neurons in the bed nucleus of the stria terminalis (BNST) drive negative affective behaviors, thus agents that decrease activity of these cells may be of therapeutic interest. Here, we show that acute restraint stress increases cFos expression in CRF neurons in the mouse dorsal BNST, consistent with a role for these neurons in stress-related behaviors. We find that activation of α2A-adrenergic receptors (ARs) by the agonist guanfacine reduced cFos expression in these neurons both in stressed and unstressed conditions. Further, we find that α- and β-ARs differentially regulate excitatory drive onto these neurons. Pharmacological and channelrhodopsin-assisted mapping experiments suggest that α2A-ARs specifically reduce excitatory drive from parabrachial nucleus (PBN) afferents onto CRF neurons. Given that the α2A-AR is a Gi-linked GPCR, we assessed the impact of activating the Gi-coupled DREADD hM4Di in the PBN on restraint stress regulation of BNST CRF neurons. CNO activation of PBN hM4Di reduced stress-induced Fos in BNST Crh neurons. Further, utilizing Prkcd as an additional marker of BNST neuronal identity, we uncovered a female-specific upregulation of the co-expression of Prkcd/Crh in BNST neurons following stress, which was prevented by ovariectomy. These findings show that stress activates BNST CRF neurons, and that α2A-AR activation suppresses the in vivo activity of these cells, at least in part by suppressing excitatory drive from PBN inputs onto CRF neurons.SIGNIFICANCE STATEMENTStress is a major variable contributing to mood disorders. Here, we show that stress increases activation of BNST CRF neurons that drive negative affective behavior. We find that the clinically well-tolerated α2A-AR agonist guanfacine reduces activity of these cells in vivo, and reduces excitatory PBN inputs onto these cells ex vivo Additionally, we uncover a novel sex-dependent co-expression of Prkcd with Crh in female BNST neurons after stress, an effect abolished by ovariectomy. These results demonstrate input-specific interactions between NE and CRF, and point to an action by which guanfacine may reduce negative affective responses.

During the Zika epidemic in Brazil, a baby was born at term with microcephaly and arthrogryposis. The mother had Zika symptoms at 10 weeks of gestation. At 17 weeks, ultrasound showed cerebral malformation and ventriculomegaly. At 24 weeks, the amniotic fluid contained ZIKV RNA and at birth, placenta and maternal blood were also positive using RT-qPCR. At birth the baby urine contained ZIKV RNA, whereas CSF at birth and urine at 17 days did not. Seizures started at 6 days. EEG was abnormal and CT scan showed cerebral atrophy, calcifications, lissencephaly, ventriculomegaly, and cerebellar hypoplasia. Bacterial sepsis at 2 months was treated. A sudden increase in head circumference occurred at 4 months necessitating ventricle-peritoneal shunt placement. At 5 months, the infant died with sepsis due to bacterial meningitis. Neuropathological findings were as severe as some of those found in neonates who died soon after birth, including hydrocephalus, destructive lesions/calcification, gliosis, abnormal neuronal migration, dysmaturation of nerve cells, hypomyelination, loss of descending axons, and spinal motor neurons. ZIKV RNA was detected only in frozen brain tissue using RT-qPCR, but infected cells were not detected by in situ hybridization. Progressive gliosis and microgliosis in the midbrain may have contributed to aqueduct compression and subsequent hydrocephalus. The etiology of progressive disease after in utero infection is not clear and requires investigation.

The central amygdala (CeA) is important for fear responses to discrete cues. Recent findings indicate that the CeA also contributes to states of sustained apprehension that characterize anxiety, although little is known about the neural circuitry involved. The stress neuropeptide corticotropin releasing factor (CRF) is anxiogenic and is produced by subpopulations of neurons in the lateral CeA and the dorsolateral bed nucleus of the stria terminalis (dlBST). Here we investigated the function of these CRF neurons in stress-induced anxiety using chemogenetics in male rats that express Cre recombinase from a Crh promoter. Anxiety-like behavior was mediated by CRF projections from the CeA to the dlBST and depended on activation of CRF1 receptors and CRF neurons within the dlBST. Our findings identify a CRFCeA→CRFdlBST circuit for generating anxiety-like behavior and provide mechanistic support for recent human and primate data suggesting that the CeA and BST act together to generate states of anxiety.SIGNIFICANCE STATEMENT Anxiety is a negative emotional state critical to survival, but persistent, exaggerated apprehension causes substantial morbidity. Identifying brain regions and neurotransmitter systems that drive anxiety can help in developing effective treatment. Much evidence in rodents indicates that neurons in the bed nucleus of the stria terminalis (BST) generate anxiety-like behaviors, but more recent findings also implicate neurons of the CeA. The neuronal subpopulations and circuitry that generate anxiety are currently subjects of intense investigation. Here we show that CeA neurons that release the stress neuropeptide corticotropin-releasing factor (CRF) drive anxiety-like behaviors in rats via a pathway to dorsal BST that activates local BST CRF neurons. Thus, our findings identify a CeA→BST CRF neuropeptide circuit that generates anxiety-like behavior.

Abstract

BACKGROUND:

Vertical transmission of Zika virus (ZIKV) leads to infection of neuroprogenitor cells and destruction of brain parenchyma. Recent evidence suggests that the timing of infection as well as host factors may affect vertical transmission. As a result, congenital ZIKV infection may only become clinically apparent in the postnatal period.

OBJECTIVES:

We sought to develop an outbred mouse model of ZIKV vertical transmission to determine if the timing of gestational ZIKV exposure yields phenotypic differences at birth and through adolescence. We hypothesized that later gestational inoculations would only become apparent in adolescence.

METHODS:

To better recapitulate human exposures, timed pregnant Swiss-Webster dams (n=15) were subcutaneously inoculated with 1x104PFU of first passage contemporary ZIKV HN16 strain or a mock injection on embryonic day 4, 8, or 12 with bioactive anti-interferon alpha receptor antibody administered in days preceding and proceeding inoculation. The antibody was given to prevent the robust type I interferon signaling cascade that make mice inherently resistant to ZIKV infection. At birth and adolescence (6 weeks of age) offspring were assessed for growth, brain weight and biparietal head diameters (BPD), and ZIKV viral levels by RT-PCR or in situ hybridization.

RESULTS:

Pups of ZIKV-infected dams infected at e4 and e8 but not e12 were growth restricted (p<0.003). Brain weights were significantly smaller at birth (p=0.01) for e8 ZIKV-exposed offspring. At 6 weeks of age, biparietal diameters (BPD) were smaller for all ZIKV exposed males and females (p<0.05), with e8 exposed males smallest by BPD and growth restriction measurements (weight >2 SD, p=0.0007). All pups and adolescent mice were assessed for ZIKV infection by RT-PCR. Analysis of all underweight pups reveled one to be positive for neuronal ZIKV infection by in situ hybridization, while a second moribund animal was diffusely positive at 8 days of age by ZIKV infectivity throughout the brain, kidneys and intestine.

CONCLUSION:

These findings demonstrate that postnatal effects of infection occurring at single time points continue to be detrimental to offspring in the postnatal period in a subset of littermates and subject to a window of gestational susceptibility coinciding with placentation. This model recapitulates frequently encountered clinical scenarios in non-endemic regions, including the majority of the U.S., where travel related exposure occurs in short and well-defined windows of gestation. Our low rate of infection and relatively rare evidence of congenital Zika syndrome parallels human population-based data.

Zika virus (ZIKV), an emerging flavivirus, has recently spread explosively through the Western hemisphere. In addition to symptoms including fever, rash, arthralgia, and conjunctivitis, ZIKV infection of pregnant women can cause microcephaly and other developmental abnormalities in the fetus. We report herein the results of ZIKV infection of adult rhesus macaques. Following subcutaneous infection, animals developed transient plasma viremia and viruria from 1-7 days post infection (dpi) that was accompanied by the development of a rash, fever and conjunctivitis. Animals produced a robust adaptive immune response to ZIKV, although systemic cytokine response was minimal. At 7 dpi, virus was detected in peripheral nervous tissue, multiple lymphoid tissues, joints, and the uterus of the necropsied animals. Notably, viral RNA persisted in neuronal, lymphoid and joint/muscle tissues and the male and female reproductive tissues through 28 to 35 dpi. The tropism and persistence of ZIKV in the peripheral nerves and reproductive tract may provide a mechanism of subsequent neuropathogenesis and sexual transmission.

The development of interventions to prevent congenital Zika syndrome (CZS) has been limited by the lack of an established nonhuman primate model. Here we show that infection of female rhesus monkeys early in pregnancy with Zika virus (ZIKV) recapitulates many features of CZS in humans. We infected 9 pregnant monkeys with ZIKV, 6 early in pregnancy (weeks 6-7 of gestation) and 3 later in pregnancy (weeks 12-14 of gestation), and compared findings with uninfected controls. 100% (6 of 6) of monkeys infected early in pregnancy exhibited prolonged maternal viremia and fetal neuropathology, including fetal loss, smaller brain size, and histopathologic brain lesions, including microcalcifications, hemorrhage, necrosis, vasculitis, gliosis, and apoptosis of neuroprogenitor cells. High-resolution MRI demonstrated concordant lesions indicative of deep gray matter injury. We also observed spinal, ocular, and neuromuscular pathology. Our data show that vascular compromise and neuroprogenitor cell dysfunction are hallmarks of CZS pathogenesis, suggesting novel strategies to prevent and to treat this disease.

Voluntary urination ensures that waste is eliminated when safe and socially appropriate, even without a pressing urge. Uncontrolled urination, or incontinence, is a common problem with few treatment options. Normal urine release requires a small region in the brainstem known as Barrington's nucleus (Bar), but specific neurons that relax the urethral sphincter and enable urine flow are unknown. Here we identify a small subset of Bar neurons that control the urethral sphincter in mice. These excitatory neurons express estrogen receptor 1 (BarESR1), project to sphincter-relaxing interneurons in the spinal cord and are active during natural urination. Optogenetic stimulation of BarESR1 neurons rapidly initiates sphincter bursting and efficient voiding in anesthetized and behaving animals. Conversely, optogenetic and chemogenetic inhibition reveals their necessity in motivated urination behavior. The identification of these cells provides an expanded model for the control of urination and its dysfunction.

Understanding the neural framework behind appetite control is fundamental to developing effective therapies to combat the obesity epidemic. The paraventricular hypothalamus (PVH) is critical for appetite regulation, yet, the real-time, physiological response properties of PVH neurons to nutrients are unknown. Using a combination of fiber photometry, electrophysiology, immunohistochemistry, and neural manipulation strategies, we determined the population dynamics of four molecularly delineated PVH subsets implicated in feeding behavior: glucagon-like peptide 1 receptor (PVHGlp1r), melanocortin-4 receptor (PVHMc4r), oxytocin (PVHOxt), and corticotropin-releasing hormone (PVHCrh). We identified both calorie- and state-dependent sustained activity increases and decreases in PVHGlp1r and PVHCrh populations, respectively, while observing transient bulk changes of PVHMc4r, but no response in PVHOxt, neurons to food. Furthermore, we highlight the role of PVHGlp1r neurons in orchestrating acute feeding behavior, independent of the anti-obesity drug liraglutide, and demonstrate the indispensability of PVHGlp1r and PVHMc4r, but not PVHOxt or PVHCrh neurons, in body weight maintenance.