title: Chronic Intermittent Sucrose Consumption Facilitates the Ability to Discriminate Opioid Receptor Blockade with Naltrexone in Rats

authors: Jewett, David C.

subjects: Science & Technology

abstract: The opioid antagonist naltrexone (NTX) decreases intake of preferred diets in rats at very low doses relative to doses needed to decrease intake of “bland” laboratory chow. In the absence of an opioid agonist, NTX is not discriminable using operant techniques. In the current study, we found that rats given intermittent access to a 25% sucrose solution learned to discriminate between various naltrexone doses and saline. None of the rats given only water learned to discriminate between naltrexone and saline. When access to the sucrose solution was discontinued for 14 days, the rats lost the ability to discriminate between NTX and saline. We also studied the changes of c-Fos IR in selected brain regions in rats treated with saline versus NTX that were drinking water or 25% sucrose. An injection of NTX or saline resulted in a significant drug, diet, and interaction effect in various brain regions associated with feeding behavior, particularly the amygdala, accumbens, and hypothalamic sites. Thus, we found that ingestion of a sucrose solution results in the ability of rats to reliably discriminate naltrexone administration. In addition, sucrose and naltrexone altered c-Fos IR in an interactive fashion in brain regions known to be involved in ingestion behavior.

text: Chronic Intermittent Sucrose Consumption Facilitates the Ability to Discriminate Opioid Receptor Blockade with Naltrexone in Rats The opioid antagonist naltrexone (NTX) decreases intake of preferred diets in rats at very low doses relative to doses needed to decrease intake of “bland” laboratory chow. In the absence of an opioid agonist, NTX is not discriminable using operant techniques. In the current study, we found that rats given intermittent access to a 25% sucrose solution learned to discriminate between various naltrexone doses and saline. None of the rats given only water learned to discriminate between naltrexone and saline. When access to the sucrose solution was discontinued for 14 days, the rats lost the ability to discriminate between NTX and saline. We also studied the changes of c-Fos IR in selected brain regions in rats treated with saline versus NTX that were drinking water or 25% sucrose. An injection of NTX or saline resulted in a significant drug, diet, and interaction effect in various brain regions associated with feeding behavior, particularly the amygdala, accumbens, and hypothalamic sites. Thus, we found that ingestion of a sucrose solution results in the ability of rats to reliably discriminate naltrexone administration. In addition, sucrose and naltrexone altered c-Fos IR in an interactive fashion in brain regions known to be involved in ingestion behavior.

year: 2022-03-01

title: Ab initio molecular dynamics investigation of beryllium complexes

authors: Raymond, Onyekachi

subjects: Science & Technology

abstract: Structures of aqueous [Be(H₂O)₄]²⁺, its outer-sphere and inner-sphere complexes with F⁻, Cl⁻, and SO₄²⁻, and dinuclear complexes with a [Be₂(κ-OH)(κ-SO₄)]⁺ core have been studied through Car–Parrinello molecular dynamics (CPMD) simulations with the BLYP functional. According to constrained CPMD/BLYP simulations and pointwise thermodynamic integration, the free energy of deprotonation of [Be(H₂O)₄]²⁺ and its binding free energy with F⁻ are 9.6 and −6.2 kcal/mol, respectively, in good accord with available experimental data. The computed activation barriers for replacing a water ligand in [Be(H₂O)₄]²⁺ with F⁻ and SO₄²⁻, 10.9 and 13.6 kcal/mol, respectively, are also in good qualitative agreement with available experimental data. These ligand-substitution reactions are indicated to follow associative interchange mechanisms with backside (SN2-like) attack of the anion relative to the aquo ligand it is displacing. Outperforming static density functional theory computations of the salient kinetic and thermodynamic quantities involving simple polarizable continuum solvent models, CPMD simulations are validated as a promising tool for studying the structures and speciation of beryllium complexes in aqueous solution.

text: Ab initio molecular dynamics investigation of beryllium complexes Structures of aqueous [Be(H₂O)₄]²⁺, its outer-sphere and inner-sphere complexes with F⁻, Cl⁻, and SO₄²⁻, and dinuclear complexes with a [Be₂(κ-OH)(κ-SO₄)]⁺ core have been studied through Car–Parrinello molecular dynamics (CPMD) simulations with the BLYP functional. According to constrained CPMD/BLYP simulations and pointwise thermodynamic integration, the free energy of deprotonation of [Be(H₂O)₄]²⁺ and its binding free energy with F⁻ are 9.6 and −6.2 kcal/mol, respectively, in good accord with available experimental data. The computed activation barriers for replacing a water ligand in [Be(H₂O)₄]²⁺ with F⁻ and SO₄²⁻, 10.9 and 13.6 kcal/mol, respectively, are also in good qualitative agreement with available experimental data. These ligand-substitution reactions are indicated to follow associative interchange mechanisms with backside (SN2-like) attack of the anion relative to the aquo ligand it is displacing. Outperforming static density functional theory computations of the salient kinetic and thermodynamic quantities involving simple polarizable continuum solvent models, CPMD simulations are validated as a promising tool for studying the structures and speciation of beryllium complexes in aqueous solution.

year: 2020

title: The sociocultural impact of tourism on the Te Arawa people of Rotorua, New Zealand

authors: Te Awekotuku, Ngahuia

subjects: Te Arawa

abstract: This is a study of how tourism in New Zealand has affected a major tribal community; their insights, reactions, and experiences. Covering five generations, it presents an oral account of the actively concerned social groups. Wherever possible, or necessary, this is reiterated and reinforced by the written record.

The work comprises two parts, the first which outlines the historic background according to available documentation, and the second which focusses on particular aspects of tribal culture and experience. Material for this section, otherwise unrecorded, came from the narrated stories, reminiscences, and often shrewd observations of the people themselves. It deals with residential community, song and dance, arts and crafts, and the role of women.

As an essentially ethnographic commentary, the study does not examine the economic features or effects of tourism, except where fiscal factors are pertinent to the understanding or continuity of the Te Arawa experience of the tourist world.

text: The sociocultural impact of tourism on the Te Arawa people of Rotorua, New Zealand This is a study of how tourism in New Zealand has affected a major tribal community; their insights, reactions, and experiences. Covering five generations, it presents an oral account of the actively concerned social groups. Wherever possible, or necessary, this is reiterated and reinforced by the written record.

The work comprises two parts, the first which outlines the historic background according to available documentation, and the second which focusses on particular aspects of tribal culture and experience. Material for this section, otherwise unrecorded, came from the narrated stories, reminiscences, and often shrewd observations of the people themselves. It deals with residential community, song and dance, arts and crafts, and the role of women.

As an essentially ethnographic commentary, the study does not examine the economic features or effects of tourism, except where fiscal factors are pertinent to the understanding or continuity of the Te Arawa experience of the tourist world.

year: 1981