Mattacks, Christine A.; Sadler, Dawn and Pond, Caroline M.
The control of lipolysis in perinodal and other adipocytes by lymph node and adipose tissue-derived dendritic cells in rats.
To simulate local, chronic, low-level inflammation, the hind-legs of adult male rats were injected subcutaneously with 20 µg lipopolysaccharide 3 times/week for 2 weeks. Dendritic cells were collected by chemokine stimulation from samples of popliteal, mesenteric and omental adipose tissue defined by their anatomical relations to lymphoid structures, and from mesenteric and popliteal lymph nodes. Dendritic cells from autologous adipose tissue stimulated lipolysis in collagenase-isolated adipocytes, and those from lymph nodes inhibited it, without and with norepinephrine at 10-5 M. All effects were stronger in near-lymph node samples or omental milky spots, and after lipopolysaccharide stimulation. All effects on adipocytes from the nodeless perirenal depot were negligible.
More [3H]-CGP 12177 (-adrenoreceptor ligand) and [3H]-RX 821002 (2A-adrenoreceptor ligand) bound to membranes of perinodal adipocytes than others. Repeated lipopolysaccharide-stimulation increased the former but decreased the latter. Effects of pre-incubating tissue explants with C6Kine, chloroethylclonidine, yohimbine or prazosin on ligand binding were complex, with omentum contrasting with popliteal and mesentery.
These data show that dendritic cells in lymphoid tissue-containing depots can modulate adipocyte lipolysis. This capacity may enable dendritic cells to acquire fatty acids from contiguous adipocytes. Site-specific differences in adrenoreceptor manifestation may specialize adipocytes to interact locally with embedded dendritic cells.
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