Probiotic effect of ferulic acid esterase-producing Lactobacillus plantarum inoculated alfalfa silage on digestion, antioxidant, and immunity status of lactating dairy goats.

A feeding experiment was conducted to determine the effects of inoculating alfalfa silage with a ferulic acid esterase-producing inoculum on feed digestibility, rumen fermentation, antioxidant, and immunity status of lactating dairy goats. Twenty dairy goats were distributed into 2 experimental groups consisting of control diet (Lp MTD/1, including Lactobacillus plantarum MTD/1 inoculated silage) against diet containing silage treated with ferulic acid esterase-producing L. plantarum A1 (Lp A1). Alfalfa silage inoculated with a ferulic acid esterase-producing Lp A1 had better fermentation quality than the Lp MTD/1 inoculation. The application of Lp A1 improved silage antioxidant capacity as indicated by greater total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and glutathion peroxidase (GSH-Px) activities in Lp A1 treated silage versus Lp MTD/1 treatment. Compared with Lp MTD/1 treated group, inoculation of silage with Lp A1 increased apparent total tract digestibility of dietary dry matter, organic matter and crude protein, and ruminal concentrations of total volatile fatty acids, acetate, propionate and isobutyrate as well. The results of current study also demonstrated improved antioxidant capacity and immune performance of dairy goats with Lp A1 inoculation. Feeding Lp A1-treated silage increased dairy goats' serum antioxidase activity, such as T-AOC, SOD, GSH-Px and catalase, and the serum concentration of immunoglobulin A, while decreased tumor necrosis factor α, interleukin (IL)-2 and IL-6. In addition, compared with Lp MTD/1, diet containing alfalfa silage inoculated with Lp A1 endowed dairy goats' milk with greater fat and protein contents, improved dairy goat milk quality without affecting feed efficiency.

A tissue-like neurotransmitter sensor for the brain and gut.

Neurotransmitters play essential roles in regulating neural circuit dynamics both in the central nervous system as well as at the peripheral, including the gastrointestinal tract1-3. Their real-time monitoring will offer critical information for understanding neural function and diagnosing disease1-3. However, bioelectronic tools to monitor the dynamics of neurotransmitters in vivo, especially in the enteric nervous systems, are underdeveloped. This is mainly owing to the limited availability of biosensing tools that are capable of examining soft, complex and actively moving organs. Here we introduce a tissue-mimicking, stretchable, neurochemical biological interface termed NeuroString, which is prepared by laser patterning of a metal-complexed polyimide into an interconnected graphene/nanoparticle network embedded in an elastomer. NeuroString sensors allow chronic in vivo real-time, multichannel and multiplexed monoamine sensing in the brain of behaving mouse, as well as measuring serotonin dynamics in the gut without undesired stimulations and perturbing peristaltic movements. The described elastic and conformable biosensing interface has broad potential for studying the impact of neurotransmitters on gut microbes, brain-gut communication and may ultimately be extended to biomolecular sensing in other soft organs across the body.

Piezo1-Mediated Ca2+ Activities Regulate Brain Vascular Pathfinding during Development.

During development, endothelial tip cells (ETCs) located at the leading edge of growing vascular plexus guide angiogenic sprouts to target vessels, and thus, ETC pathfinding is fundamental for vascular pattern formation in organs, including the brain. However, mechanisms of ETC pathfinding remain largely unknown. Here, we report that Piezo1-mediated Ca2+ activities at primary branches of ETCs regulate branch dynamics to accomplish ETC pathfinding during zebrafish brain vascular development. ETC branches display spontaneous local Ca2+ transients, and high- and low-frequency Ca2+ transients cause branch retraction through calpain and branch extension through nitric oxide synthase, respectively. These Ca2+ transients are mainly mediated by Ca2+-permeable Piezo1 channels, which can be activated by mechanical force, and mutating piezo1 largely impairs ETC pathfinding and brain vascular patterning. These findings reveal that Piezo1 and downstream Ca2+ signaling act as molecular bases for ETC pathfinding and highlight a novel function of Piezo1 and Ca2+ in vascular development.

Role of Olfactorily Responsive Neurons in the Right Dorsal Habenula-Ventral Interpeduncular Nucleus Pathway in Food-Seeking Behaviors of Larval Zebrafish.

The habenula (Hb) plays important roles in emotion-related behaviors. Besides receiving inputs from the limbic system and basal ganglia, Hb also gets inputs from multiple sensory modalities. Sensory responses of Hb neurons in zebrafish are asymmetrical: the left dorsal Hb and right dorsal Hb (dHb) preferentially respond to visual and olfactory stimuli, respectively, implying different functions of the left and right dHb. While visual responses of the left dHb (L-dHb) have been implicated in light-preference behavior, the significance of olfactory responses of the right dHb (R-dHb) remains under-examined. It was reported that the R-dHb can gate innate attraction to a bile salt. However, considering a broad range of odors that R-dHb respond to, it is of interest to examine the role of R-dHb in other olfactory behaviors, especially food seeking, which is essential for animals' survival. Here, using in vivo whole-cell recording and calcium imaging, we first characterized food extract-evoked responses of Hb neurons. Responsive neurons preferentially locate in the R- but not L-dHb and exhibit either ON- (~87%) or OFF-type responses (~13%). Interestingly, this right-to-left asymmetry of olfactory responses converts into a ventral-to-dorsal pattern in the interpeduncular nucleus (IPN), a main downstream target of Hb. Combining behavior assay, we further found that genetic dysfunction or lesion of the R-dHb and its corresponding downstream ventral IPN (V-IPN) impair the food seeking-associated increase of swimming activity. Thus, our study indicates that the asymmetrical olfactory response in the R-dHb to V-IPN pathway plays an important role in food-seeking behavior of zebrafish larvae.

The Locus Coeruleus Modulates Intravenous General Anesthesia of Zebrafish via a Cooperative Mechanism.

How general anesthesia causes loss of consciousness has been a mystery for decades. It is generally thought that arousal-related brain nuclei, including the locus coeruleus (LC), are involved. Here, by monitoring locomotion behaviors and neural activities, we developed a larval zebrafish model for studying general anesthesia induced by propofol and etomidate, two commonly used intravenous anesthetics. Local lesion of LC neurons via two-photon laser-based ablation or genetic depletion of norepinephrine (NE; a neuromodulator released by LC neurons) via CRISPR/Cas9-based mutation of dopamine-ß-hydroxylase (dbh) accelerates induction into and retards emergence from general anesthesia. Mechanistically, in vivo whole-cell recording revealed that both anesthetics suppress LC neurons' activity through a cooperative mechanism, inhibiting presynaptic excitatory inputs and inducing GABAA receptor-mediated hyperpolarization of these neurons. Thus, our study indicates that the LC-NE system plays a modulatory role in both induction of and emergence from intravenous general anesthesia.

[The structure and function of habenula].

The habenula (Hb) is an evolutionarily conserved diencephalic structure in vertebrates. It is considered as an emotion center and plays critical roles in regulating diverse types of emotion-related behaviors, including anxiety, fear, reward, depression, and nicotine withdrawal. On the one hand, action selection- and emotion-relevant inputs are transferred to the Hb through the basal ganglia and limbic system, respectively. At the same time, sensory inputs of multiple modalities also converge on the Hb. Among them, the visual input of the Hb from the retina ganglion cells ‒ thalamus pathway has been found to play a critical role in light-preference behavior of zebrafish. On the other hand, the Hb projects to two main neuromodulatory systems, the dopaminergic system and the serotoninergic system. As the Hb receives both internal emotion inputs and external sensory inputs and regulates the function of neuromodulatory systems, its functions are quite diverse and complex. In this review, we summarize the progress in both the structure and connection of the Hb and propose future study direction.

Left Habenula Mediates Light-Preference Behavior in Zebrafish via an Asymmetrical Visual Pathway.

Habenula (Hb) plays critical roles in emotion-related behaviors through integrating inputs mainly from the limbic system and basal ganglia. However, Hb also receives inputs from multiple sensory modalities. The function and underlying neural circuit of Hb sensory inputs remain unknown. Using larval zebrafish, we found that left dorsal Hb (dHb, a homolog of mammalian medial Hb) mediates light-preference behavior by receiving visual inputs from a specific subset of retinal ganglion cells (RGCs) through eminentia thalami (EmT). Loss- and gain-of-function manipulations showed that left, but not right, dHb activities, which encode environmental illuminance, are necessary and sufficient for light-preference behavior. At circuit level, left dHb neurons receive excitatory monosynaptic inputs from bilateral EmT, and EmT neurons are contacted mainly by sustained ON-type RGCs at the arborization field 4 of retinorecipient brain areas. Our findings discover a previously unidentified asymmetrical visual pathway to left Hb and its function in mediating light-preference behavior. VIDEO ABSTRACT.

Visual Cue-Discriminative Dopaminergic Control of Visuomotor Transformation and Behavior Selection.

Animals behave differently in response to visual cues with distinct ethological meaning, a process usually thought to be achieved through differential visual processing. Using a defined zebrafish escape circuit as a model, we found that behavior selection can be implemented at the visuomotor transformation stage through a visually responsive dopaminergic-inhibitory circuit module. In response to non-threatening visual stimuli, hypothalamic dopaminergic neurons and their positively regulated hindbrain inhibitory interneurons increase activity, suppressing synaptic transmission from the visual center to the escape circuit. By contrast, threatening visual stimuli inactivate some of these neurons, resulting in dis-inhibition of the visuomotor transformation and escape generation. The distinct patterns of dopaminergic-inhibitory neural module's visual responses account for this stimulus-specific visuomotor transformation and behavioral control. Thus, our study identifies a behavioral relevance-dependent mechanism that controls visuomotor transformation and behavior selection and reveals that neuromodulation can be tuned by visual cues to help animals generate appropriate responses.

Intron-based genomic editing: a highly efficient method for generating knockin zebrafish.

The TALEN and CRISPR/Cas9 nuclease systems have been extensively utilized in genomic engineering of model organisms. In zebrafish, the nuclease systems have been successfully applied in generating loss-of-function knockout lines. However, genome-specific knockin techniques in zebrafish are still at the beginning. In this perspective, we briefly summarize the recent progresses on knockin approaches in zebrafish with a special focus on the newly developed intron-based knockin method.

The antidepressant effects and mechanism of action of total saponins from the caudexes and leaves of Panax notoginseng in animal models of depression.

Total saponins extracted from the caudexes and leaves of Panax notoginseng (SCLPN) have been used in the clinic for improving mental function, treating insomnia, and alleviating anxiety. The present study evaluated the potential antidepressant activity of SCLPN in rodent models of depression and the mechanism of action of SCLPN. Mice were received SCLPN at doses of 10-1000 mg/kg daily for 1, 7, and 14 days and then were subjected to the forced swim test and locomotor activity test. The results showed that SCLPN decreased immobility time in the forced swim test, with little effect on locomotion. In the chronic mild stress model, chronic SCLPN treatment (70 mg/kg) reversed the rats' depression-like behavior. Furthermore, SCLPN exerted its antidepressant-like effect by increasing the levels of 5-hydroxytryptamine, dopamine, and noradrenaline. Additionally, SCLPN treatment reduced intracellular Ca(2+) in cultured neurons. The present study suggests that SCLPN may function as an antidepressant, and the antidepressant-like effects of SCLPN may be mediated by modulation of brain monoamine neurotransmitters and intracellular Ca(2+) concentration.