Rat gonadotropin-releasing hormone receptor expressed in insect cells induces activation of adenylyl cyclase.

Increasing evidence exist that multiple G proteins mediate the effects of gonadotropin-releasing hormone (GnRH) on the synthesis and release of pituitary gonadotropins. In the present study, we have expressed the rat GnRH receptor (GnRH-R) in insect cells, by infection with a recombinant baculovirus. Under the conditions used, insect cells expressed, 48 h post-infection, a maximum of 7800 +/- 650 receptors/cell which bound GnRH agonist [D-Trp6]GnRH with a Kd = 0.

Modulation of membrane fluidity and lipidic metabolism in transformed rat fibroblasts induced by the sesquiterpenic hormone farnesylacetone.

Farnesylacetone is a natural terpene extracted from androgenic glands of the crustacean Carcinus maenas and is capable of inhibiting proliferation, notably in transformed mammalian cells. Flow cytometry with three lipophilic probes, diphenylhexatriene, trimethylammonium-diphenylhexatriene, and Nile red, has revealed modifications of the lipidic metabolism in transformed FR3T3-mTT4 rat fibroblasts treated by farnesylacetone, including changes in membrane fluidity. Farnesylacetone strongly increased the number of neutral lipidic droplets in the cytoplasm.

Modulation of fibroblast response to maitotoxin along the cell division cycle.

Maitotoxin (MTX) induces an increase of [Ca2+]i and of phosphoinositide breakdown in various cell types. The [Ca2+]i increase followed with fluorescent probes on cell suspensions has been described as slow and lasting, in contrast to the "signal" induced by calcium ionophores such as ionomycin. MTX effects have been studied on two fibroblastic cell lines, BHK21 C13 and FR 3T3, synchronized by serum deprivation treatment performed in an isoleucine-free medium for BHK21 C13 cells.

Farnesylacetone, a sesquiterpenic hormone of Crustacea, inhibits electron transport in isolated rat liver mitochondria.

Farnesylacetone (C18 H30 0) is a male hormone extracted from the androgenic gland of crab, Carcinus maenas. Appropriate enzymatic assays, as well as spectrophotometric studies, indicate that micromolar concentrations of farnesylacetone interact with the electron transport pathway of rat liver mitochondria. By the use of artificial electron donors and electron acceptors, it is shown that farnesylacetone immediately inhibits the electron transfer within complex I (NADH ubiquinone reductase activity) and complex II (succinate ubiquinone reductase activity).

Comparative effect of farnesylacetone on macromolecular synthesis in gonads of crustaceans.

Farnesylacetone, a molecule isolated from the androgenic glands of Carcinus maenas, inhibits vitellogenesis in the ovaries. Here the effect of farnesylacetone on protein and RNA synthesis in cultured organs is described. Both leucine and uridine incorporation in ovaries were inhibited with low concentration of farnesylacetone.