PubMed Health⌕ Search

Biomedical subjects

R C Pierce

Publications and source records attributed to R C Pierce.

49 records · Page 3Linked to original sources
PubMed1990

Changes in locomotion and dopamine neurotransmission following amphetamine, haloperidol, and exposure to novel environmental stimuli.

Locomotor behavior and dopamine (DA) neurotransmission were assessed in rats exposed to either a novel or familiar stimulus environment while under the influence of amphetamine, haloperidol or saline. The behavioral results indicated that, as expected, amphetamine increased horizontal locomotor activity in a dose-dependent manner. Exposure to novelty also increased horizontal activity, and this behavioral effect was disrupted by both amphetamine and haloperidol. Regardless of whether the animals were exposed to the novel or familiar stimulus environment, amphetamine increased DA synthesis in the nigrostriatal system, but not in the mesolimbic system, whereas haloperidol increased DA synthesis in both the nigrostriatal and mesolimbic systems. Amphetamine also decreased DA metabolism and haloperidol increased DA metabolism in both the nigrostriatal and mesolimbic systems. In contrast, exposure to novelty alone was without effect on DA synthesis or metabolism in any region examined, suggesting that novelty-induced hyperactivity and amphetamine-induced hyperactivity involve different neurochemical mechanisms. However, exposure to novelty while under the influence of haloperidol produced a significant increase in DA metabolism in both the nigrostriatal and mesolimbic systems. These latter results suggest that exposure to novelty may produce a measurable activation of DA systems when the autoreceptors involved in the negative feedback loop are blocked.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Naloxone enhances the expression of morphine-induced conditioned place preference.

The present study examined the effects of naloxone on acquisition and expression of morphine-induced conditioned place preference (CPP). Three groups of rats were given morphine (5 mg/kg, SC), both morphine and naloxone (1 mg/kg, SC), or saline paired with a distinctive environment. On alternating days they were given saline paired with another distinctive environment. After four exposures to each environment, the animals were given a preference test in which they had access to both environments simultaneously while under the influence of either naloxone (1 mg/kg, SC) or saline. Morphine-conditioned animals showed CPP evident as an increased amount of time spent in the drug-associated environment relative to saline controls. Rats given both naloxone and morphine during conditioning, and saline on the test day, did not show CPP. In contrast, morphine-conditioned animals given naloxone on the test day showed stronger CPP than morphine-conditioned animals given saline. These findings indicate that naloxone blocks the acquisition, but enhances the expression of morphine-induced CPP. In a separate experiment, the effects of naloxone on locomotor activity were determined during the CPP test. The results indicated that naloxone decreased locomotor activity. In morphine-conditioned animals only, naloxone also produced an increase in the amount of time per entry in the drug-associated environment. The results suggest that naloxone may enhance morphine-induced CPP by decreasing locomotor activity that may otherwise compete with expression of CPP.

Animals↗
PubMed1990

Effect of forebrain dopamine depletion on novelty-induced place preference behavior in rats.

Novelty-induced place preference behavior of rats was studied in two experiments. In the first experiment, separate groups of animals were habituated to a distinct environment 30 min daily for either zero, one, two, four or eight days. On the day following the last habituation day, animals were allowed 15 min free access to both the habituated (familiar) and a distinct novel environment. The results revealed a significant novelty preference in the two-, four- and eight-day habituation groups. In these same animals, the rate of horizontal and vertical activity was lower in the novel environment relative to the familiar environment. The influence of forebrain dopamine (DA) projections on novelty preference behavior was studied in the second experiment. Animals were given an injection of 6-hydroxydopamine (6-OHDA) into the nucleus accumbens or were given sham surgery, and then they were given four habituation days to one environment. Novelty-induced place preference was blocked in the lesioned animals, as the amount of time spent in the novel and familiar environments was not significantly different. Lesioned animals also failed to show a difference in locomotor activity between the novel and familiar environments. Subsequent assay data revealed that the 6-OHDA lesion reduced DA levels in the nucleus accumbens, anterior striatum and olfactory tubercles by over 65% as compared to sham surgery. These results suggest that novelty preference behavior may be mediated by a central DA pathway similar to that involved in other types of reinforcing stimuli, such as food, water and drugs of abuse.

Animals↗
PubMed1989

Novelty-induced place preference behavior in rats: effects of opiate and dopaminergic drugs.

In Experiment 1, adult male rats were given eight 30-min exposures to one of two distinct environments. Control animals received either four exposures to each environment or were not exposed to either environment. When given free-choice access to both environments simultaneously, animals spent significantly more time in the novel environment relative to the familiar environment. In these same animals, horizontal and vertical activity rates were lower in the novel environment than in the familiar environment. In Experiments 2-5, animals were assessed for novelty preference behavior under the influence of either morphine (0, 0.1, 0.3, 1.0 or 3.0 mg/kg), naltrexone (0, 0.1, 0.3 or 1.0 mg/kg), amphetamine (0, 0.1, 0.3 or 1.0 mg/kg) or haloperidol (0, 0.03, 0.1, 0.3 or 1.0 mg/kg). Haloperidol produced a dose-dependent disruption in novelty preference behavior, while all other drugs tested were without effect. Haloperidol also disrupted the novelty-induced decrease in horizontal and vertical activity rates. These results suggest that haloperidol blocks the reinforcing and locomotor-depressant effects of a novel environment in a free-choice preference test.

Amphetamines↗
PubMed1982

Antecedents of symptom expression during marital separation.

Examined the role of possible antecedents of psychological symptoms among 310 recently separated men and women. Hierarchical set regression analysis indicated that socio-demographic variables generally are unrelated to symptom expression, although age, gender, length of marriage, and length of separation did predict either agitated depressive or stress symptoms. Several dimensions of social stressors contributed to the prediction of one or more of six symptom factors, but symptoms also were associated with current psychological well-being. These results suggest that the symptomatology of divorcing persons can be partitioned into that which is consequent to the disruptive conditions encountered in divorce and that which may reflect characteristic levels of mental health.

Adaptation, Psychological↗
PubMed1981

The influence of stress upon symptom structure.

Evaluated the influence of stress on the factor structure of symptoms in a nonclinical population. A random sample of 299 persons in the process of divorcing were subdivided into those high and low on stressful life events. Separate factor analyses of symptoms for each group provided evidence that stress does affect symptom structure. Ruminative Depression was the only stable factor. Two anxiety factors from the low stress group merged into one factor among the high stressed, while agitated depression appeared only in the low stress condition. A factor suggestive of stress response syndrome was evident among the high stressed.

Adult↗
PubMed1979

Dimensions of adult self-concept.

A 70-item adjective checklist was administered to four groups of adults as part of a longitudinal study of psychosocial change during four normative transitions. Data gathered at two times with a five-year interval were cluster analyzed separately. Six clusters were extracted from the first set of data, 7 from the second, with minor changes in dimensionality: all 6 original clusters had counterparts in the second analysis, but some dimensional change was seen in all but one cluster. The argument is made that although such dimensional change is often treated as error or completely ignored in longitudinal research, this inattention can lead to serious problems in the interpretation of results.

Adolescent↗
PubMed1976

Cleavage of phycocyanobilin from C-phycocyanin. Separation and mass spectral identification of the products.

The chromophore of C-phycocyanin, phycocyanobilin, was cleaved from the protein with methanol, concentrated hydrochloric acid, or subtilisin BPN'. The pigments obtained were converted to their dimethyl esters and purified by preparative high pressure liquid chromatography and examined for purity by analytical high pressure chromatography on silica gel. They were characterized by proton transfer and electron impact mass spectroscopy. The principal product obtained by the three cleavage procedures was phycocyanobilin. Methanol and hydrochloric acid adducts of phycocyanobilin were obtained with methanol and concentrated hydrochloric acid cleavages, respectively. Methanol adduct formation of phycocyanobilin can occur subsequent to cleavage and requires acid catalysis. No adduct formation was observed with mesobiliverdin under similar conditions. These results and mass spectral data support the conclusion that adduct formation takes place at the exocyclic olefin linkage of ring A in phycocyanobilin. The ease of co-valent adduct formation strongly suggests that the ethylidene side chain is an important binding site of phycocyanobilin to the polypeptide chain.

Cyanobacteria↗