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Biomedical subjects

R H Lenox

Publications and source records attributed to R H Lenox.

At least 91 records · Page 5Linked to original sources
PubMed1984

Effects of chronic lead exposure on release of endogenous catecholamines: a preliminary communication.

The release of endogenous dopamine and norepinephrine from six brain regions (cortex, hippocampus, hypothalamus, striatum, s. nigra, n. accumbens-o. tubercle) of chronically lead-exposed rats was compared to release from controls. Prenatal and postnatal chronic lead intoxication was induced by 1000 ppm lead acetate in the drinking water of dams 70 days prior to mating and throughout gestation and lactation. Offspring were also maintained on 1000 ppm lead acetate until sacrificed at approximately 60 days of age. Release was measured in vitro from tissue minces prepared from both lead-exposed and control rats. There were no significant differences in spontaneous or potassium-stimulated norepinephrine release between lead-exposed and control rats. Potassium and amphetamine both stimulated striatal dopamine release; however, no marked differences between lead-exposed and control tissue were seen. Potassium-stimulated release of dopamine from the nucleus accumbens-olfactory tubercle area was increased in the lead-exposed animals. This is interesting in light of the postulated role of the n. accumbens in the central regulation of motor activity and the reported alterations in activity in lead-exposed rodents.

Animals↗
PubMed1983

Automated analysis of stereotypic behavior induced by psychomotor stimulants.

A newly developed rotation sensing device has been applied to the continuous monitoring of animal movement. Animals treated with morphine, amphetamine or apomorphine display different stereotypic movements which can be distinguished by the apparatus. Initial studies have indicated that the apparatus is able not only to identify but also to quantitate some measures of stereotypic behavior. For example, the number and direction of rotations (a measure of motor asymmetry), frequency of changes in movement direction (a measure of stereotypic movement) and periods of cessation of movement are affected differentially with acute morphine, apomorphine or amphetamine treatment. Moreover, using this apparatus, morphine was shown to increase the degree of rotational asymmetry of normal animals and of animals with unilateral lesions of the nigrostriatal pathway.

Amphetamine↗
PubMed1983

Comparison of stress response in male and female rats: pituitary cyclic AMP and plasma prolactin, growth hormone and corticosterone.

Three potent stressors (forced running, immobilization, and footshock) were found to increase levels of cyclic AMP in the pituitaries of both female and male rats. The pituitary cyclic AMP response in females was generally similar to that observed in males. The tested stressors elevated both plasma corticosterone and prolactin and decreased plasma growth hormone. Plasma corticosterone rose more rapidly in females than in males following stress. Control growth hormone levels were higher in male rats. There was no clear cause and effect relationship between elevations of pituitary cyclic AMP and changes in plasma levels of prolactin, corticosterone, and growth hormone.

Animals↗
PubMed1982

Cyclic AMP and cyclic GMP response to stress in brain and pituitary: stress elevates pituitary cyclic AMP.

Male rats were exposed to six stressors (saline injection, cold, forced running, Formalin injection, immobilization, electric footshock) for 15, 30, or 60 min. Following sacrifice by microwave irradiation, cyclic AMP and cyclic GMP levels were measured in pituitary, pineal and 8 regions of rat brain. All stressors except saline increased plasma corticosterone, plasma prolactin and pituitary cyclic AMP levels compared to control animals. The magnitude of the pituitary cyclic AMP response was highly correlated with the intensity of the stress as determined by the levels of plasma prolactin. Electric footshock increased pituitary cyclic AMP levels over 10 fold and plasma prolactin over 60 fold. Cyclic AMP levels in other brain regions were not altered. Cerebellar cyclic GMP was increased only by stressors that involved increased motor activity.

Animals↗
PubMed1982

A device for the automated monitoring of stereotypic behavior.

1. A novel rotation sensing device has been developed which consists of a linear potentiometer attached to the top of a spherical testing chamber. The potentiometer constantly monitors the precise angular position of the animal inside the chamber. 2. This device allows the automated monitoring of direction and rate of rotation, as well as a variety of other stereotypic behaviors. 3. The effects of morphine, apomorphine and amphetamine on motor activity were assessed by the apparatus.

Amphetamine↗
PubMed1981

Protein phosphorylation mediates effects of isoproterenol on adenylate cyclase activity in rat cortical membranes.

The effects of (-)-isoproterenol on adenylate cyclase activity were studied in rat cerebral cortical membranes prepared and assayed in the presence of calcium ions. In assays carried out in the presence of high Mg2+ concentrations (5-10 mM) and of Ca2+ in the micromolar range, addition of 1-100 micro M (-)-isoproterenol caused over 50% inhibition of adenylate cyclase activity. Since these conditions are optimal for supporting endogenous phosphorylative activity in synaptic membranes, we tested whether the observed effects are mediated by changes in the phosphorylation of specific proteins in these membranes. This was done by preincubation of lysed synaptosomes under phosphorylating conditions in the presence and absence of isoproterenol followed by extensive washes and analysis of cyclic AMP formation in resuspended membranes. Addition of (-)-isoproterenol to the preincubation resulted in a 30% decrease of adenylate cyclase activity in the reincubation. Inclusion of [gamma-32P]ATP in the preincubation and examination of the phosphorylation state of specific proteins in membranes entering the reincubation revealed that (-)-isoproterenol inhibited the phosphorylation of a specific protein band with apparent molecular weight of 47,000 (designated band F). These results support the hypothesis that alterations in membrane protein phosphorylation induced by neurotransmitters play a role in the regulation of adenylate cyclase activity.

Adenosine Triphosphate↗