G. Thornetjomsland et Jc. Jamieson, TIME-COURSE STUDY OF THE GOLGI-LYSOSOME REGION OF RAT HEPATOCYTES DURING EARLY ACUTE-PHASE RESPONSE TO INFLAMMATION, The Anatomical record, 244(1), 1996, pp. 15-27
Background: In a previous study of the hepatocyte Golgi apparatus 24 h
r following the induction of the acute phase response to inflammation,
it was found that the predominant secretory content was a granulofila
mentous material (GFM), rather than lipoprotein particles (LP) as in c
ontrols (Thorne-Tjomsland and Jamieson, 1995, Anat. Rec., 241:439-450)
. The present study aimed to determine when and how this switch occurs
and to monitor the Golgi-lysosome region of hepatocytes in general du
ring early inflammation. Methods: Rats were injected with turpentine o
il as an inflammatory agent. At 1, 2, 6, 12, and 16 hr after turpentin
e-injection (TI), the livers were prefixed by perfusion with cacodylat
e-buffered glutaraldehyde, postfixed with ferrocyanide reduced osmium,
and processed for thin section transmission electron microscopy. Resu
lts: LP were processed at all time points between 1 and 16 hr post-TI,
and at 1 and 2 hr post-TI, the Golgi stacks were engorged with LP and
therefore apparently processed more of these particles than in contro
ls. A GFM was processed at later time points, starting at 12 hr post-T
I. At the two time points when LP and GFM were co-processed, these mat
erials were frequently seen sorted from each other within the trans-sa
ccule and/or the trans-Golgi network (TGN). At the level of the TGN, t
hese materials were packaged into secretory vesicles which typically c
ontained LP and/or GFM. Massive depletion of cytoplasmic glycogen was
observed primarily at 1, 2, and 6 hr following TI. Concomitantly and t
emporarily, glycogen accumulated within Golgi-associated lysosome-like
bodies with extensive appendages. Conclusions: The switch in Golgi ap
paratus secretory content from LP to GFM occurred at around 12 hr post
-TI, but was not discrete. The initial appearance of the GFM coincided
with the initial increase in the serum of hepatocyte-derived acute ph
ase reactants (see review Schreiber et al., 1989, Ann. NY Acad. Sci.,
557: 61-85). An additional and surprising finding of the present study
was that significant changes occurred in the Golgi-lysosome region mu
ch prior to the onset of acute phase reactant synthesis: 1 and 2 hr po
st-TI, the Gels processed above-normal amounts of LP and Golgi-associa
ted, lysosome-like bodies sequestered glycogen. (C) 1996 Wiley-Liss, I
nc.