Primate neuronal connections are sparse in cortex as compared to mouse

Serotonin transporter (SERT) modulates the level of 5-HT and significantly affects the activity of serotonergic neurons in the central nervous system. The manipulation of SERT has lasting neurobiological and behavioral consequences, including developmental dysfunction, depression, and anxiety. Auditory disorders have been widely reported as the adverse events of these mental diseases. It is unclear how SERT impacts neuronal connections/interactions and what mechanism(s) may elicit the disruption of normal neural network functions in auditory cortex. In the present study, we report on the neuronal morphology and function of auditory cortex in SERT knockout (KO) mice. We show that the dendritic length of the fourth layer (L-IV) pyramidal neurons and the second-to-third layer (L-II/III) interneurons were reduced in the auditory cortex of the SERT KO mice. The number and density of dendritic spines of these neurons were significantly less than those of wild-type neurons. Also, the frequency-tonotopic organization of primary auditory cortex was disrupted in SERT KO mice. The auditory neurons of SERT KO mice exhibited border frequency tuning with high-intensity thresholds. These findings indicate that SERT plays a key role in development and functional maintenance of auditory cortical neurons. Auditory function should be examined when SERT is selected as a target in the treatment for psychiatric disorders.

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Microglia Regulate Neuronal Circuits in Homeostatic and High-Fat Diet-Induced Inflammatory Conditions

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2021.722028 ◽

2021 ◽

Vol 15 ◽

Author(s):

Xiao-Lan Wang ◽

Lianjian Li

Keyword(s):

High Fat Diet ◽

Microglial Activation ◽

Current Knowledge ◽

Brain Diseases ◽

High Fat ◽

Synaptic Remodeling ◽

Inflammatory Conditions ◽

Cellular Debris ◽

Neuronal Connections ◽

Almost All

Microglia are brain resident macrophages, which actively survey the surrounding microenvironment and promote tissue homeostasis under physiological conditions. During this process, microglia participate in synaptic remodeling, neurogenesis, elimination of unwanted neurons and cellular debris. The complex interplay between microglia and neurons drives the formation of functional neuronal connections and maintains an optimal neural network. However, activation of microglia induced by chronic inflammation increases synaptic phagocytosis and leads to neuronal impairment or death. Microglial dysfunction is implicated in almost all brain diseases and leads to long-lasting functional deficiency, such as hippocampus-related cognitive decline and hypothalamus-associated energy imbalance (i.e., obesity). High-fat diet (HFD) consumption triggers mediobasal hypothalamic microglial activation and inflammation. Moreover, HFD-induced inflammation results in cognitive deficits by triggering hippocampal microglial activation. Here, we have summarized the current knowledge of microglial characteristics and biological functions and also reviewed the molecular mechanism of microglia in shaping neural circuitries mainly related to cognition and energy balance in homeostatic and diet-induced inflammatory conditions.

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Establishment of an Olfactory Region-specific Intranasal Delivery Technique in Mice to Target the Central Nervous System

Frontiers in Pharmacology ◽

10.3389/fphar.2021.789780 ◽

2022 ◽

Vol 12 ◽

Author(s):

Johannes Flamm ◽

Sunniva Hartung ◽

Stella Gänger ◽

Frank Maigler ◽

Claudia Pitzer ◽

...

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Ct Scan ◽

Systemic Circulation ◽

Intranasal Delivery ◽

Step Procedure ◽

Delivery Technique ◽

Neuronal Connections ◽

The Central Nervous System ◽

Cns Delivery

We have recently developed a region-specific catheter-based intranasal application method in mice by using CT scan-based 3D cast models of the murine nose (DOI: 10.2376/0005-9366-17,102). This technique is able to specifically deliver drugs to the olfactory region or to the respiratory region only. Thereby, intranasally administered drugs could be delivered either via neuronal connections to the central nervous system or via the well-perfused rostral parts of the nasal mucosa to the systemic circulation. In the present study, we transferred successfully this novel delivery technique to C57Bl/6 mice and determined parameters such as insertions depth of the catheter and maximum delivery volume in dependence to the weight of the mouse. Breathing was simulated to verify that the volume remains at the targeted area. A step-by-step procedure including a video is presented to adopt this technique for standardized and reproducible intranasal central nervous system (CNS) delivery studies (DOI: 10.3390/pharmaceutics13111904).

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Dactyl Sensory Influences on Rock Lobster Locomotion: II. ROLE IN INTERLEG COORDINATION

Journal of Experimental Biology ◽

10.1242/jeb.148.1.113 ◽

1990 ◽

Vol 148 (1) ◽

pp. 113-128 ◽

Cited By ~ 1

Author(s):

U. W. E. MÜLLER ◽

FRANÇOIS CLARAC

Keyword(s):

Electrical Stimulation ◽

Sensory Nerve ◽

Movement Pattern ◽

Rock Lobster ◽

Step Cycle ◽

Extreme Position ◽

Walking Pattern ◽

Neuronal Connections ◽

Phase Relationships ◽

Stimulation Of

1. The effects of cyclic electrical stimulation of the dactyl sensory nerve (DN) on the walking pattern of rock lobsters were examined at the two crucial points within the step cycle: the anterior extreme position (AEP) and the posterior extreme position (PEP). 2. Stimulation during the occurrence of the PEP affected neither the movement pattern of the stimulated leg itself nor that of the ipsilateral adjacent legs. 3. Stimulation of the same intensity during the occurrence of the AEP interrupted the oscillation of the stimulated leg and affected the phase relationships of the ipsilateral adjacent legs. 4. The possibility that indirect influences were mediated by coupling to the substratum can be excluded. Neuronal connections may therefore exist between the funnel canal organs (FCO) of a single leg and the motor output of the adjacent legs. The discussion deals with whether the described channels alone are able to fulfil the requirements of a ‘coordinating mechanism’ as described in the literature.

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