azacosterol and mevalonolactone

Sterol components of mouse submandibular, sublingual and parotid glands were studied by thin-layer and gas-liquid chromatography. The major sterol was cholesterol (5-cholesten-3 beta-ol; 26.7, 28.0, 18.8 micrograms/mg protein respectively), with minor amounts of squalene, lathosterol (5 alpha-cholest-7-en-3 beta-ol), desmosterol (cholesta-5,24-dien-3 beta-ol), lanosterol (4,4',14-trimethyl-5 alpha-cholesta-8,24-dien-3 beta-ol), dihydrolanosterol (4,4',14-trimethyl-5 alpha-cholest-8-en-3 beta-ol) and methylstenol. Chromatograms of salivary sterols were similar to those of liver, and different from those of skin in which the amount of lathosterol was much higher. Administration of the anticholesterolaemic agent, 20,25-diazacholesterol, resulted in accumulation of desmosterol in all tissues tested, and additional sterols also accumulated in skin. The gas-liquid chromatographic profiles of salivary sterols from the treated animals were similar to those of liver, but different from those of skin. Thus sterols were synthesized in salivary glands and the biosynthetic pathway was via C24-unsaturated side-chain intermediates, as in liver. This was verified by showing that [2-14C]-mevalonate was incorporated into sterols in vitro when it was incubated with homogenates of these glands.

Topics: Animals; Azacosterol; Cholesterol; Chromatography, Gas; Chromatography, Thin Layer; In Vitro Techniques; Liver; Male; Mevalonic Acid; Mice; Mice, Inbred Strains; Salivary Glands; Skin; Sterols

In this report, we examine the requirement of cholesterol biosynthesis and its axonal transport for goldfish optic nerve regeneration. Cholesterol, labeled by intraocular injection of [3H]mevalonolactone, exhibited a delayed appearance in the optic tectum. Squalene and other minor components were labeled but not transported. Following optic nerve crush, the amount of labeled cholesterol transport was elevated, while retinal labeling was not altered relative to control fish. A requirement for cholesterol biosynthesis is inferred from the inhibition of neurite outgrowth in retinal explants caused by the cholesterol synthesis inhibitor, 20,25-diazacholesterol. The inhibition of growth could be overcome by addition of mevalonolactone, but not cholesterol, to the medium. Intraperitoneal administration of 200 nmol of diazacholesterol resulted in 92-98% inhibition of retinal cholesterol synthesis and accumulation of labeled desmosterol and other lipids in fish retina and brain which persisted for 2 weeks. Diazacholesterol-treated fish showed no reduction in the amount of lipid-soluble radioactivity transported following intraocular injection of [3H]mevalonolactone, but there were alterations in the chromatographic pattern of the transported labeled lipids. In contrast to its effects on neurite outgrowth in vitro, diazacholesterol did not inhibit optic nerve regeneration in vivo, as measured both by arrival of labeled rapidly transported protein at the tectum and by time required for the return of visual function.

Topics: Animals; Axons; Azacosterol; Cholesterol; Desmosterol; Goldfish; Mevalonic Acid; Nerve Regeneration; Optic Nerve; Retina