Rodney D. Johnson

Learn More
Endocrine-disrupting chemicals (EDCs), particularly those that affect the hypothalamic-pituitary-gonadal (HPG) axis of vertebrates, have become a focus of regulatory screening and testing throughout the world. Small fish species, principally the fathead minnow (Pimephales promelas), Japanese medaka (Oryzias latipes), and zebrafish (Danio rerio), are used as(More)
The pharmacological properties of the alpha-adrenoceptors which increase cyclic AMP accumulation were studied in slices of rat cerebral cortex after inactivation of beta-adrenoceptors with bromoacetylalprenololmenthane. Norepinephrine increased basal cyclic AMP accumulation 2-fold, and potentiated the effect of adenosine 5-fold. The Ki and EC50 values for(More)
The properties of alpha-1 adrenergic receptors in rat cerebral cortex were examined by measuring increases in [3H]inositol metabolism in brain slices. Slices of rat cerebral cortex were incubated in the presence of 0.23 microM [3H]inositol in Krebs-Ringer-bicarbonate buffer containing 10 mM lithium chloride, and the production of water-soluble [3H]inositol(More)
The relationship between norepinephrine-stimulated phosphatidyl-inositol metabolism and alpha 1-adrenergic receptor density was examined in rat brain. Increases in phosphatidyl-inositol metabolism were determined by accumulation of [3H]inositol phosphates in the presence of lithium in brain slices, while receptor density was determined by specific binding(More)
Activation of alpha 1-adrenergic receptors in slices of rat brain increases inositol phosphate accumulation, increases basal cyclic AMP accumulation, and potentiates the increase in cyclic AMP caused by adenosine. We compared these three responses to determine whether they are mediated by the same receptors. The increase in inositol phosphates and the(More)
Some species of animals and some early developmental stages of other species are capable of central nervous system (CNS) regeneration. These species and developmental stages also have reduced or absent allergic reaction to tissue homografts. Mammals are allergic to their own brain antigens, and experimental allergic encephalomyellitis (EAE) can be produced(More)
Correlational evidence suggests that specific populations of animals have been, or currently are being, adversely affected by exposure to environmental contaminants that manifest effects through different endocrine systems. However, there currently are insufficient data to resolve the ecological risk associated with endocrine-disrupting chemicals (EDCs). In(More)
Conazoles are designed to inhibit cytochrome P450 (CYP) 14α-demethylase, an enzyme key to fungal cell wall formation. In vertebrates, conazoles may inhibit other CYPs, potentially disrupting processes like sex steroid synthesis. Propiconazole is a current-use pesticide that is among the first chemicals being tested in the U.S. Environmental Protection(More)
Incidental findings from animal experiments involving administration of exogenous opioid agonists indicate that there are close links between the endogenous opioid system and feeding behaviour. Subsequent investigations aimed at elucidating the nature of the opioid-feeding relationship led to a wide variety of findings, some of them apparently(More)
Pharmaceuticals and personal care products (PPCPs) are emerging contaminants that have been found ubiquitously in wastewater and surface waters around the world. A major source of these compounds is incomplete metabolism in humans and subsequent excretion in human waste, resulting in discharge into surface waters by wastewater treatment plant (WWTP)(More)