Carla Filipa Simões Henriques - IBILI, University of Coimbra
Title: Chronic blockade of adenosine A2A receptors: gender-specific reprogramming of microglia morphology in the pre-frontal cortex
Abstract:
In adulthood, microglia (cells implicated in the genesis of anxiety) present morphologic differences between genders in physiological conditions (1). Under prenatal anxiogenic stimulus, these cells undergo gender-specific morphological remodelling. In these circumstances, the chronic blockade of adenosine A2A receptors (A2AR), a modulator of microglia, ameliorated microglia morphology and anxiety behavior in males, but not in females (1). This dimorphic response is likely related with gender differences in the density of A2AR in the pre-frontal cortex (PFC), brain region strictly involved in anxiety disorders (1). It is thus imperative to study microglia morphology in the PFC from early neurodevelopment onwards, as well as the physiologic response to A2AR manipulation in males and females.
The present study aims to clarify whether gender-specific microglia morphology is already present in newborns (post-natal day, PND 0) and infants (PND 7) in the PFC. Our second goal is to characterize the effect of the chronic blockade of A2AR in adulthood (PND 90) in microglia morphology in the PFC of male and female rats.
Wistar rats were treated with SCH58261 (SCH) (0.1 mg/kg/day, intraperitoneal), a selective A2AR antagonist, for 21 consecutive days before PND 90. Microglia morphology was assessed by immunohistochemistry with a microglia marker (Iba-1). Confocal images obtained with a 63x objective, allowed the manual reconstruction of microglia in 3D using Neurolucida software. Statistic analysis was performed in GraphPad Prism: Student’s t test was used to compare two independent means; differences were considered significant at p<0.05.
Microglia volume at PND 0 was similar between genders (NT males: 2749 ± 391.2 μm3; NT females: 2376 ± 198.9 μm3, n=3, p>0.05); at PND 7 we still did not observe gender differences in ramifications number and length (n=3, p>0.05) in PFC microglia. At PND 90, the chronic blockade of A2AR reduced the number and length of microglial processes in females (NT females, n=6, vs SCH females, n=7, p<0.05), but did not affect males (n=4, p>0.05).
In conclusion, the present data show that A2AR control microglia morphology in a gender-specific manner. On the other hand, we characterized for the first time microglia morphology in the PFC of newborn rats, showing that gender differences in microglia morphology are not present until PND 7, which coincides with an endogenous peak of A2AR expression.
Title: Chronic blockade of adenosine A2A receptors: gender-specific reprogramming of microglia morphology in the pre-frontal cortex
Abstract:
In adulthood, microglia (cells implicated in the genesis of anxiety) present morphologic differences between genders in physiological conditions (1). Under prenatal anxiogenic stimulus, these cells undergo gender-specific morphological remodelling. In these circumstances, the chronic blockade of adenosine A2A receptors (A2AR), a modulator of microglia, ameliorated microglia morphology and anxiety behavior in males, but not in females (1). This dimorphic response is likely related with gender differences in the density of A2AR in the pre-frontal cortex (PFC), brain region strictly involved in anxiety disorders (1). It is thus imperative to study microglia morphology in the PFC from early neurodevelopment onwards, as well as the physiologic response to A2AR manipulation in males and females.
The present study aims to clarify whether gender-specific microglia morphology is already present in newborns (post-natal day, PND 0) and infants (PND 7) in the PFC. Our second goal is to characterize the effect of the chronic blockade of A2AR in adulthood (PND 90) in microglia morphology in the PFC of male and female rats.
Wistar rats were treated with SCH58261 (SCH) (0.1 mg/kg/day, intraperitoneal), a selective A2AR antagonist, for 21 consecutive days before PND 90. Microglia morphology was assessed by immunohistochemistry with a microglia marker (Iba-1). Confocal images obtained with a 63x objective, allowed the manual reconstruction of microglia in 3D using Neurolucida software. Statistic analysis was performed in GraphPad Prism: Student’s t test was used to compare two independent means; differences were considered significant at p<0.05.
Microglia volume at PND 0 was similar between genders (NT males: 2749 ± 391.2 μm3; NT females: 2376 ± 198.9 μm3, n=3, p>0.05); at PND 7 we still did not observe gender differences in ramifications number and length (n=3, p>0.05) in PFC microglia. At PND 90, the chronic blockade of A2AR reduced the number and length of microglial processes in females (NT females, n=6, vs SCH females, n=7, p<0.05), but did not affect males (n=4, p>0.05).
In conclusion, the present data show that A2AR control microglia morphology in a gender-specific manner. On the other hand, we characterized for the first time microglia morphology in the PFC of newborn rats, showing that gender differences in microglia morphology are not present until PND 7, which coincides with an endogenous peak of A2AR expression.