Female rats (200 g) were fed a nutritionally adequate diet containing 1% by weight of corn oil (low-fat, LF), 21% of corn oil (CO) or 20% of beef tallow plus 1% of corn oil (BT) for two weeks. Food was removed for 8–12 hr, then each rat was refed for 1 hr. Each rat was injected ip with Na-3H-acetate and U-14C-Na-palmitate, (P),-oleate (O) or-linoleate (L). Expired CO2 was collected for 2 hr. Liver, heart and serum were obtained for analysis of total lipid14C and3H and cholesterol14C and3H. Oxidation of L was twice as great as O or P when the LF diet was fed. CO and BT diets doubled oxidation of O to equal L, and increased oxidation of P, 50%. In liver and serum P was retained to a greater extent than O or L on BT and CO diets. Incorporation of acetate into total lipid was highest on LF diet and reduced by feeding either CO or BT. Incorporation of acetate into cholesterol was greater when BT or CO was fed than for LF.14C was incorporated into cholesterol in such small amounts that it was barely detectable and could not be counted accurately. Conclusions are that (a) dietary fat affects rate of oxidation of uniformly labeled palmitate and oleate, but not linoleate, (b) acetate is a more ready precursor to cholesterol than is fatty acid carbon, and (c) the acetate incorporated into cholesterol when polyunsaturated fat is fed is not derived directly from fatty acid carbon. The failure of incorporation of fatty acid carbon into cholesterol within 2 hr of administration opens the question of compartmentation of acetate as to its metabolic source.

Dietary lipid, fatty acid oxidation and incorporation of carbon into cholesterol.

Biosynthesis of cholesterol from stearate in a cell-free system.

In vitro hepatic cholesterogenesis in rats fed corn oil and fat-free diets.

Ultrastructural changes of the brain of rats that inhaled marijuana cigarettes for 8 weeks were examined by electron microscopy, simultaneously with immunohistochemical investigation for serotonergic neuronal activities in the nucleus accumbens (NAc), the hippocampus (CA-1) and the nucleus raphe dorsalis (NRD). In the animals that inhaled marijuana, numerous cored and coated vesicles were observed near the well-developed Golgi apparatus of the NRD neurons. The lamellar membranous structure was found frequently in the dendrite, and occasionally in the axon, and the synapse of the marijuana-smoking animals. The serotonin-immunostainability in neurons of the NRD was significantly stronger in the animals that inhaled marijuana than in the non-treated ones. The serotonin-immunostainability in nerve fibers and terminals of the NAc and the CA-1 showed an obvious decrease compared with that of the non-treated animals. These findings suggest that the neurons in the NRD that is the original nucleus of the serotonergic nerve system have become functionally hyperactive by Δ9-tetrahydrocannabinol, but it may induce the dysfunction of serotonin transmission from the original nucleus.

Immacolata Caccia Perugini

Papers

Biosynthesis of cholesterol from long-chain fatty acids in cell-free systems from rat liver