AJP - Regulatory, Integrative and Comparative Physiology, Vol 249, Issue 3 355-R359, Copyright © 1985 by American Physiological Society
Neurohumoral stimulation of lipogenesis during altered states of energy balance
R. B. Melnyk, J. D. Hallonquist and J. M. Martin
Acid extracts of bovine hypothalamus stimulate lipogenic activity in
adipose tissue. We employed a rat fat cell bioassay system to determine
whether tissue concentrations of the active material vary as a function of
spontaneous alterations in energy balance in hibernators and/or the obesity
resulting from bilateral electrolytic lesions of the ventromedial area of
the hypothalamus in rats. When hypothalamic extracts and partially purified
plasma were fractionated using reverse-phase high-pressure liquid
chromatography, both the void volume and material eluting 17 min after the
start of a 25-min linear methanol gradient enhanced glucose incorporation
into total lipid. Activities eluting with these two fractions were
positively correlated with one another and were independent of insulin. The
results indicate that a hypothalamic lipogenic factor (LHF) is detectable
in plasma, that hypothalamic and circulating LHF concentrations vary in a
reciprocal manner, and that elevations in plasma LHF concentration are
associated with insulin resistance. The data suggest that the central
regulation of lipogenesis is at least partially mediated by a hypothalamic
humoral factor reaching fat depots via the circulation.
