Protocols in Current Issue
Protocols in Past Issues
0 Q&A 354 Views Jan 20, 2024

Capillary density in skeletal muscles is key to estimate exercise capacity in healthy individuals, athletes, and those with muscle-related pathologies. Here, we present a step-by-step, high-throughput semi-automated method for quantifying capillary density from whole human skeletal muscle cross-sections, in areas of the muscle occupied by myofibers. We provide a detailed protocol for immunofluorescence staining, image acquisition, processing, and quantification. Image processing is performed in ImageJ, and data analysis is conducted in R. The provided protocol allows high-throughput quantification of capillary density.

Key features

• This protocol builds upon the method and results described in Abbassi-Daloii et al. (2023b).

• It includes step-by-step details on image acquisition and image processing of the entire muscle section.

• It enables high-throughput and semi-automated image quantification of capillary density.

• It provides a robust analysis for determining capillary density over the entire muscle cross section.

Graphical overview

0 Q&A 4917 Views Sep 5, 2020
Determining the neuronal circuitry responsible for specific behaviors is a major focus in the field of neurobiology. Activity-dependent immediate early genes (IEGs), transcribed and translated shortly after neurons discharge action potentials, have been used extensively to either identify or gain genetic access to neurons and brain regions involved in such behaviors. By using immunohistochemistry for the protein product of the IEG c-Fos combined with retrograde labeling of specific neuronal populations, precise experimental timing, and identical data acquisition and processing, we present a method to quantitatively identify specific neuronal subpopulations that were active during social encounters. We have previously used this method to show a stronger recruitment of ventral hippocampal neurons that project to the medial prefrontal cortex, compared to those that project to the lateral hypothalamus, following social interactions. After optimization of surgeries for the injection of retrograde tracers, this method will be useful for the identification and mapping of neuronal populations engaged in many different behaviors.
0 Q&A 6503 Views Dec 5, 2017
Alzheimer’s disease’s established primary trigger is β-amyloid (Aβ) (Mucke and Selkoe, 2012). The amyloid precursor protein (APP) endocytosis is required for Aβ generation at early endosomes (Rajendran and Annaert, 2012). APP retention at endosomes depends on its sorting for degradation in lysosomes (Haass et al., 1992; Morel et al., 2013; Edgar et al., 2015; Ubelmann et al., 2017). The following endocytosis assay has been optimized to assess the amyloid precursor protein (APP) endocytosis and degradation by live murine cortical primary neurons (Ubelmann et al., 2017).
0 Q&A 9932 Views Jan 5, 2017
Functional connectivity in a neural circuit is determined by the strength, incidence, and neurotransmitter nature of its connections (Chuhma, 2015). Using optogenetics the functional synaptic connections between an identified population of neurons and defined postsynaptic target neurons may be measured systematically in order to determine the functional connectome of that identified population. Here we describe the experimental protocol used to investigate the excitatory functional connectome of ventral midbrain dopamine neurons, mediated by glutamate cotransmission (Mingote et al., 2015). Dopamine neurons are made light sensitive by injecting an adeno-associated virus (AAV) encoding channelrhodopsin (ChR2) into the ventral midbrain of DATIREScre mice. The efficacy and specificity of ChR2 expression in dopamine neurons is verified by immunofluorescence for the dopamine-synthetic enzyme tyrosine hydroxylase. Then, slice patch-clamp recordings are made from neurons in regions recipient to dopamine neuron projections and the incidence and strength of excitatory connections determined. The summary of the incidence and strength of connections in all regions recipient to dopamine neuron projections constitute the functional connectome.

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