TGF-beta 1 mRNA increases in macrophage/microglial cells of the hippocampus in response to deafferentation and kainic acid-induced neurodegeneration.
This study examined TGF-beta 1 mRNA levels and cellular localization in the F344 rat hippocampus following deafferentation or kainic acid (KA)-induced neurodegeneration. By RNA solution hybridization, TGF-beta 1 transcripts were at low prevalence in intact adult rat hippocampus (0.02 pg/microgram total RNA). Four days after unilateral entorhinal cortex lesioning (ECL), TGF-beta 1 mRNA increased threefold in the ipsilateral hippocampus. This increase was localized to the outer molecular layer of the dentate gyrus, where gliosis, synapse loss, and synaptic reorganization occur. TGF-beta 1 mRNA also increased in the hippocampus after KA-induced limbic seizures, particularly in the areas of the hippocampus undergoing neurodegeneration. Microglia [OX-42 immunoreactive (IR) cells] responded to these two lesions with distinct morphological changes. Combined immunocytochemistry-in situ hybridization showed that TGF-beta 1 mRNA was localized to reactive microglia (OX-42-IR, with blunt processes), but not to resting ramified microglia (OX-42-IR, with numerous fine processes) or to astrocytes (GFAP-IR). After ECL, round macrophage-like cells (OX-42-IR with TGF-beta 1 mRNA) were seen at the wound site. Thus, brain macrophage/microglial cells produce TGF-beta 1 mRNA in the hippocampus in response to deafferentation and neurodegeneration.
Ethel Percy Andrus Gerontology Center, University of Southern California, Los Angeles 90089-0191.
T E
TE
Morgan
N R
NR
Nichols
G M
GM
Pasinetti
C E
CE
Finch
D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis / Q000235:genetics; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D007608:Kainic Acid / Q000633:toxicity*; D008032:Limbic System / Q000503:physiopathology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008648:Mesoderm; D009410:Nerve Degeneration / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology; D013702:Temporal Lobe / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000096:biosynthesis* / Q000235:genetics
D005904:Glial Fibrillary Acidic Protein; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D007608:Kainic Acid