Morphological study of 5-HT neurons and astroglial cells on brain of adult rats perinatal or chronically exposed to 2,4-dichlorophenoxyacetic acid.
2,4-D is a chlorophenoxyherbicide used worldwide. We have studied the morphological alterations of 5-HT neurons and glial cells in the mesencephalic nuclei of adult rats exposed to 2,4-D both perinatally (during pregnancy and lactation) and chronically (during pregnancy, lactation and after weaning) with quantitative methods. Pregnant rats were daily exposed to 70 mg/kg of 2,4-D from gestation day (GD) 16 to post-natal day (PND) 23 through diet. After weaning, pups were assigned to one of two sub-groups: T1 (fed with untreated diet until PND 90) and T2 (maintained with 2,4-D diet until PND 90). Brain sections were immunocytochemically stained using polyclonal anti-5-HT, anti-GFAP and anti-S-100 protein antibodies as cells markers. 2,4-D exposure during pregnancy and lactancy (T1 group) produced an increase in 5-HT neuronal area and immunoreactivity (IR) in the mesencephalic nuclei studied. However, with the chronical 2,4-D exposure (T2 group) only the 5-HT neuronal area from the dorsal raphe nucleus (DRN) was increased, suggesting an adaptable response of 5-HT neurons in median raphe nucleus (MRN). The presence of reactive astrocytes in mesencephalic nuclei and in hippocampus were also different for the two 2,4-D exposure designs, showing the existence of a correspondence between neuronal changes and astrogliosis. Results support evidences that 2,4-D alters the serotoninergic system and that 5-HT neurons of each mesencephalic nuclei show different responses to the 2,4-D exposure designs which are parallel to astrogliosis.
Garcia
G
G
Experimental Toxicology Laboratory, School of Biochemical and Pharmaceutical Sciences, National University of Rosario, Santa Fe, Argentina.
Tagliaferro
P
P
Bortolozzi
A
A
Madariaga
M J
MJ
Brusco
A
A
Evangelista de Duffard
A M
AM
Duffard
R
R
Saavedra
J P
JP
D015084:2,4-Dichlorophenoxyacetic Acid / Q000633:toxicity*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000648:ultrastructure*; D001921:Brain / Q000166:cytology*; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006540:Herbicides / Q000633:toxicity*; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D007202:Indicators and Reagents; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000648:ultrastructure*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011903:Raphe Nuclei / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D051381:Rats; D009418:S100 Proteins / Q000378:metabolism; D012701:Serotonin / Q000502:physiology*
D005904:Glial Fibrillary Acidic Protein; D006540:Herbicides; D007202:Indicators and Reagents; D009418:S100 Proteins; D015084:2,4-Dichlorophenoxyacetic Acid; D012701:Serotonin