Morphometric analysis of astrocytes in vocal production circuits of common marmoset (Callithrix jacchus)

Abstract

Astrocytes, the star-shaped glial cells, are the most abundant non-neuronal cell population in the central nervous system. They play a key role in modulating activities of neural networks, including those involved in complex motor behaviors. Common marmosets (Callithrix jacchus), the most vocal non-human primate (NHP), have been usedto study the physiology of vocalization and social vocal production. However, the neural circuitry involved in vocal production is not fully understood. In addition, even less is known about the involvement of astrocytes in this circuit. To understand the role, that astrocytes may play in the complex behavior of vocalization, the initial step may be to study their structural properties in the cortical and subcortical regions that are known to be involved in vocalization. Here, in the common marmoset, we identify all astrocytic subtypes seen in other primate's brains, including intralaminar astrocytes. In addition, we reveal detailed structural characteristics of astrocytes and perform morphometric analysis of astrocytes residing in the cortex and midbrain regions that are associated with vocal production. We found that cortical astrocytes in these regions illustrate a higher level of complexity when compared to those in the midbrain. We hypothesize that this complexity that is expressed in cortical astrocytes may reflect their functions to meet the metabolic/structural needs of these regions.

Whole-brain analysis of CO2chemosensitive regions and identification of the retrotrapezoid and medullary raphé nuclei in the common marmoset (Callithrix jacchus)

“…Additionally, this antibody stains a double band at 245-395kDA on Western Blot Analysis (Key et al 1993). We have recently showed that this antibody also reacts with marmoset’s astrocytes (Turk and SheikhBahaei 2021).…”

“…This GFAP antibody was raised against purified glial filament protein (Debus, Weber, & Osborn, 1983). We have previously shown the specificity of this antibody to detect astrocytes in marmoset tissue as well (Turk and SheikhBahaei 2021).…”

“…Floating slices were divided into ten series and stored in anti-freeze solution in −20 °C until staining. Coronal sections were immunostained as described before (Sheikhbahaei, Morris, et al 2018; Turk and SheikhBahaei 2021). Briefly, the brain sections (1 every 10 sections) were incubated on a shaker for 48 h at 4 °C with a primary antibody.…”

“…Those sections were subsequently incubated in secondary antibodies conjugated to the fluorescent probes (1:500; Life Technologies) for 1.5 h shaking at room temperature. A separate section before or after the one that used for antibody staining was stained with Nissl, as described before (Turk and SheikhBahaei 2021). Briefly, the tissue was stained with NeuroTrace™ green fluorescent Nissl stain (1:200 in PBS, Life Technologies, catalog No.…”

“…To identify astrocytes, we used antibodies against glial fibrillary acidic protein (GFAP). GFAP is isolated from cow spinal cord, the rabbit-polyclonal anti-GFAP antibody (1:1,000; Agilent (formerly DAKO), catalog #z-0334, RRID: AB_10013382) cross-reacts with an epitome of mouse, rat, and human cytoskeleton, the intra-cytoplasmic filamentous protein [manufacturer’s technical information; (Eng 1985; Eng et al 2000; Turk and SheikhBahaei 2021)]. Additionally, this antibody stains a double band at 245-395kDA on Western Blot Analysis (Key et al 1993).…”