NOCICEPTIVE STIMULUS IN THE NEONATAL PERIOD AFFECTS SATELLITE GLIAL CELLS MORPHOLOGY IN ADULT LIFE, WITH DIFFERENCES BETWEEN MALE AND FEMALE RATS

Abstract

Satellite glial cells (SGCs) are found in the dorsal root ganglia (DRG) surrounding completely and individually sensory neurons, forming a thin sheath cells with regulatory function of the neuronal microenvironment. During the nociceptive stimulus the SGCs are activated and express glial fibrillary acidic protein (GFAP). Sustained nociceptive stimulus may cause morphological changes in SGCs influencing the mechanisms of pain chronification that may differ between genders. Understanding the plasticity in peripheral pain pathways considering gender differences is crucial, particularly when noxious stimuli are applied to neonates, when the nervous system is still under rapid and intense remodeling. We investigated the density (number/area) of neurons in the DRG that were enveloped by GFAP immunoreactive SGCs. Male (N=6 per group) and female (N=6 per group) Wistar rats, 15 and 180 days old after neonatal nociceptive stimulation [1] were used. Right and left L5 DRG were removed, frozen and 8 μm thick criossections were incubated in rabbit polyclonal anti‐GFAP antibody (1:2.000; 24hr). Immunostaining protocol was used as described [2]. The DRG area was measured with the aid of computer software. Neurons enveloped by a ring of GFAP‐labeled SGCs were counted, their density (number/area) was calculated and data were compared between right and left sides, 15 and 180 days of age and genders. Differences were considered significant if p<0.05. There was an increased density of neurons enveloped by a ring of GFAP‐labeled SGCs on both genders, 15 days after the nociceptive stimulus, compared to controls, with females presenting a larger density of these neurons compared to males at this age, on the stimulated side. At age of 180 days, the difference between pain and control groups persisted only in females. The comparison between genders showed that males present a smaller density of neurons enveloped by a ring of GFAP‐labeled SGCs compared to females on both ages with statistical significance only at 15 days old groups. There is an extensive literature clearly pointing to the fact that men and women are different in their responses to pain. Women present increased sensitivity to pain and differ in pain intervention responsivity. Despite that sociocultural and psychological factors certainly play a role in these gender differences, evidence from animals studies reveal important, qualitative and quantitative differences at low levels of the neuroaxis. Our results add extra evidence that multiple biological factors and mechanisms underlie gender differences in sensitivity and responses to pain.Support or Funding InformationFinancial support: FAPESP, CNPq, CAPES and FAEPAThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.