RU486 administration blocks neuropeptide Y potentiation of luteinizing hormone (LH)-releasing hormone-induced LH surges in proestrous rats.

We previously demonstrated that NPY potentiates LHRH-induced LH secretion specifically under endocrine conditions in which preovulatory LH surges are generated. The present study was designed to test the hypothesis that NPY's facilitatory actions are dependent upon preovulatory progesterone secretion. In Exp 1, female rats were fitted with atrial catheters on diestrus.

Metabolism and activation of pancreas specific nitrosamines by pancreatic ductal cells in culture.

Metabolism of 14C labeled N-nitrosobis(2-oxopropyl)amine (BOP), N-nitroso(2-hydroxypropyl)(2-oxopropyl)amine (HPOP) and N-nitrosobis(2-hydroxypropyl)amine (BHP) by pancreatic duct cells in culture involves the following two pathways: reduction or oxidation reactions at the beta-carbon which result in the inter-conversion of these nitrosamines and activation reactions which result in the decomposition of the nitrosamine, the evolution of 14CO2 and the labeling of macromolecules. Reduction of BOP to HPOP seems to contribute significantly to the metabolism of the former nitrosamine by pancreatic duct cells, however, redox reactions at the beta-carbon of HPOP or BHP are not extensive. In terms of DNA damage, all three nitrosamines yield methyl and hydroxypropyl adducts.