Lipolytic agents

Glucocorticoids not only break down protein but also stimulate the catabolism of lipids in adipose tissue and enhance the actions of other lipolytic agents. This occurrence results in an increase in plasma free fatty acids and an enhanced tendency to ketosis. The mechanism of this lipolytic action is unknown. The net effect of the biochemical changes induced by the glucocorticoids is antagonism of the actions of insulin. These biochemical events promote hyperglycemia and glycosuria, which are similar to the diabetic state. 

Penicillium roqueforti and P. camemberti produce very active extracellular lipases, which are the principal lipolytic agents in mold-ripened cheeses. They preferentially hydrolyze the short-chain fatty acids in milk fat. P. roqueforti produces two lipases, one with an alkaline pH optimum and the other most active at pH 6 6.5, with slightly differing fatty acid specificities (Menassa and Lamberet, 1982). P. camemberti secretes a single lipase with optimal activity at pH 9 (Lamberet and Lenoir, 1976). 

Chernick, S. S., Spooner, P. M., Garrison, M. M., and Scow, R. O, (1986). Effect of epinephrine and other lipolytic agents on intracellular iipolysis and lipoprotein lipase activity in 3T3-LI adipocytes. /. Lipid Res. 27, 286-294. 

These results show that acipimox acts to inhibit cAMP-stimulated hpolysis through suppression of intracellular cAMP levels, with a subsequent decrease in PKA activity. The anti-lipolytic activity of acipimox is associated with a quantitative shift of HSL from the LD to the cytosol in rat adipocytes, suggesting that, by decreasing intracellular cAMP levels, acipimox can reduce the association of HSL with TAG substrate of the LD. Pharmacokinetic studies show that the plasma concentration of acipimox in man after a single 250 mg oral dose reaches 33 gM, and remains above 7 gM for 6-8 h [448]. In comparison, acipimox is a potent anti-lipolytic agent at a concentration of 10 gM and above, in human adipose tissue stimulated maximally and sub-maximally by isoproterenol [449]. Thus, plasma acipimox levels correlate well with its in vitro effect on hpolysis and cAMP synthesis in rat adipocytes. 

Laminaria is a kelp that finds its place in the brown algae family. It has been an area of study for past many years, and its wonderful biological properties have always attracted medical professionals and researchers to explore more and more from this wonder kelp. The constituents of Laminaria include iodine, potassium, magnesium, calcium and iron. Iodine compounds, TEA-hydroiodide in particular, are great lipolytic agents as they stimulate lipase activity. Laminarins on the other hand are used as a tumor angiogenic blocker. 

Another example of the importance of stereochemistry in determining physiological activity is in the finding that (—)-norlaudanosoline is a very effective lipolytic agent with isolated fat cells, whereas the (4-)-form is essentially inactive. ... 

The lipid character of membranes explains their high electrical resistance, their ready destruction by lipolytic agents, and why they are permeable to lipid-soluble materials but have a low permeability for ions and most polar molecules. The presence of protein accounts for their mechanical strength, low surface tension and high specific conductance. The membrane proteins are also responsible for the specific properties of membranes and different types of protein are found in different membranes. 

The adipose tissues of 4 different bird species, studied by Goodridge and Ball, (1964,1965 and 1966) show a distinctive profile of characteristics. As in the rabbit tissue, lipogenesis is absent and the tissue is unresponsive to either action of insulin. In responsiveness to lipolytic agents, however, the bird s tissue resembles that of the rat in possessing intense sensitivity to catechol amines and to glucagon (see also Hoak et al, 1966). 

Glucagon is a pov/erful lipolytic agent for rat adipose tissue in vitro. 

Zinnam, B., and Hollenberg, C. H., 1974, Effect of insulin and lipolytic agents on rat adipocyte low Km cyclic adenosine 3, 5 -monophosphate phosphodiesterase, J. Biol. Chem. 249 2182. 

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