Search

Nicotine is a significant public health concern because it is the primary pharmacological agent in tobacco use disorder. One neural system that has been implicated in the symptoms of several substance use disorders is the melanin-concentrating hormone (MCH) system. MCH regulates various motivated behaviors depending on sex, yet little is known of how this interaction affects experience with drugs of abuse, particularly nicotine. The goal of this study was to determine the effect of MCH receptor antagonism on experience-dependent nicotine-induced locomotion after chronic exposure, particularly on the expression of locomotor sensitization. Adult female and male Wistar rats were given saline then cumulative doses of nicotine (0.1, 0.32, 0.56, and 1.0 mg/kg) intraperitoneally to determine the acute effects of nicotine (day 1). Next, rats were treated with 1.0 mg/kg nicotine for 6 days, given an identical series of cumulative doses (day 8), and then kept in a drug-free state for 6 days. On day 15, rats were pretreated with vehicle or the MCH receptor antagonist GW803430 (10 or 30 mg/kg) before another series of cumulative doses to assess response to chronic nicotine. After vehicle, male rats increased nicotine locomotor activation from day 1 to day 15, and both sexes showed a sensitized response when normalized to saline. The lower dose of GW803430 decreased locomotion compared to vehicle in females, while the higher dose decreased locomotion in males. Both sexes showed nicotine dose-dependent effects of GW803430, strongest at lower doses of nicotine. Controlling for sex-based locomotor differences revealed that females are more sensitive to GW803430. The high dose of GW803430 also decreased saline locomotion in males. Together, the results of our study suggest that MCH is involved in the expression of nicotine locomotor sensitization, and that MCH regulates these nicotine behavioral symptoms differently across sex., Competing Interests: Declaration of competing interest None., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Glucose is the brain's primary energetic resource. The brain's use of glucose is dynamic, balancing delivery from the neurovasculature with local metabolism. Although glucose metabolism is known to differ in humans with and without methamphetamine use disorder (MUD), it is unknown how central glucose regulation changes with acute methamphetamine experience. Here, we determined how intravenous methamphetamine regulates extracellular glucose levels in a brain region implicated in MUD-like behavior, the lateral hypothalamus (LH). We measured extracellular LH glucose in awake adult male and female drug-naive Wistar rats using enzyme-linked amperometric glucose biosensors. Changes in LH glucose were monitored during a single session after: 1 ) natural nondrug stimuli (novel object presentation and a tail-touch), 2 ) increasing cumulative doses of intravenous methamphetamine (0.025, 0.05, 0.1, and 0.2 mg/kg), and 3 ) an injection of 60 mg of glucose. We found second-scale fluctuations in LH glucose in response to natural stimuli that differed by both stimulus type and sex. Although rapid, second-scale changes in LH glucose during methamphetamine injections were variable, slow, minute-scale changes following most injections were robust and resulted in a reduction in LH glucose levels. Dose and sex differences at this timescale indicated that female rats may be more sensitive to the impact of methamphetamine on central glucose regulation. These findings suggest that the effects of MUD on healthy brain function may be linked to how methamphetamine alters extracellular glucose regulation in the LH and point to possible mechanisms by which methamphetamine influences central glucose metabolism more broadly. NEW & NOTEWORTHY Enzyme-linked glucose biosensors were used to monitor lateral hypothalamic (LH) extracellular fluctuations during nondrug stimuli and intravenous methamphetamine injections in drug-naive awake male and female rats. Second-scale glucose changes occurred after nondrug stimuli, differing by modality and sex. Robust minute-scale decreases followed most methamphetamine injections. Sex differences at the minute-scale indicate female central glucose regulation is more sensitive to methamphetamine effects. We discuss likely mechanisms underlying these fluctuations, and their implications in methamphetamine use disorder.

To explore definitions, frequencies, and motivation for personal use of work computers, we analyzed 329 employees' responses to an online survey, which asked participants to self-report frequencies for 41 computer behaviors at work. This sample (65% female, 74% European ethnicity, mean age of 36 years) was formed by soliciting participants through Internet Usenet groups, emails, and listservs. Results support a distinction between computer use that is counterproductive and that which is merely not productive. Nonproductive Computer Use occurred more when employees were younger (r = -0.31, p < 0.01), had Internet access at work longer (r = +0.16, p < 0.01), and had faster Internet connections at work than at home (r = +0.14, p < 0.01). Counterproductive Computer Use occurred more when Internet access was newer (r = -0.16, p < 0.01) and employees knew others who had been warned about misuse (r = +0.11, p < 0.05). While most employees who engaged in computer counterproductivity also engaged in computer nonproductivity, the inverse was uncommon, suggesting the need to distinguish between the two when establishing computer policies and Internet accessibility.

The advent of the desktop computer has allowed organizations to help their employees become faster and more productive workers. Some employees, however, use their work computers in unproductive ways as well, such as sending personal email and playing computer games. We call this Personal Use of Work Computers (PUWC). Using a work computer for personal reasons deviates from many organizations' norms. In the current study, we surveyed employees at an educational institution and asked them to report how they use their computers at work. These respondents also answered questions related to their sensation seeking, impulsiveness, conscientiousness, and job satisfaction as well as demographic information. We found that people who use their computers in unproductive ways tend to be men, younger, more impulsive, and less conscientious. We also found that those who use their computers for riskier PUWC behaviors (like viewing sexual content) tended to have sensation seeking personalities.

This study reports the development of an instrument to assess the motives of marathon runners. The Motivations of Marathoners Scales (MOMS) contains 56 items distributed across nine scales. Content areas covered included health orientation, weight concern, self-esteem, life meaning, psychological coping, affiliation, recognition, competition, and personal goal achievement. Adequate internal consistency (Cronbach's alpha range .80 to .93), retest reliability (intraclass Rs range .71 to .90), and factorial validity of the scales were demonstrated. Assessment of the relationship between individual MOMS scales and other variables of conceptual relevance documents early evidence for the convergent and discriminant validity of the instrument. Future uses of the MOMS are discussed in light of theoretical, empirical, and practical considerations.