PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 11224320

Environment modifies the expression of behavioral sensitization produced by methamphetamine: behavioral and neurochemical studies.

T. Ohmori·T. Abekawa·T. Koyama
View original source ↗Export metadata ↓

Abstract

Effects of environmental modulation of methamphetamine (MA)-induced behavior on the establishment and mode of expression of behavioral sensitization were examined. Rats received daily injection of MA for 10 days (1mg/kg, s.c.). Half of them were immediately returned to the home cage (home cage group) and the other half were individually confined in a cylinder with a diameter of 13cm placed inside the home cage for 3h after each injection (small cage group). Gross observations revealed that rats which received MA in the small cage did not locomote but showed sniffing and rearing. The third group received saline in the home cage (saline control group). After a 7-8 day or 17-18 day withdrawal period, all groups were injected with MA (1mg/kg or 0.5mg/kg) in their home cages. The home cage group showed significant enhancement in horizontal motor activity compared to the saline control group, indicating the establishment of locomotor sensitization. In contrast, the small cage group showed no or slight enhancement in the motor activity. However, they showed significantly more stereotyped behavior compared to both the saline control and the home cage groups. Microdialysis studies revealed no enhancement in the ability of MA to increase dopamine release from the nucleus accumbens in either the home or the small cage group compared to the saline control group, when examined after either a 7-8 day or a 17-18 day withdrawal period. These results suggest that environmental modulation of actual movement under the stimulant effect modifies the pattern and character of the stimulant-induced behavior in sensitized animals. The neurochemical basis of the establishment of behavioral sensitization and the environmental modification of its expression remain unknown.

Explore related subjects

Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

T. Ohmori, T. Abekawa, T. Koyama. 1995. Environment modifies the expression of behavioral sensitization produced by methamphetamine: behavioral and neurochemical studies.. https://pubmed.ncbi.nlm.nih.gov/11224320/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2027

Effectiveness of high-dose versus standard-dose influenza vaccines against hospitalisation according to frailty risk: a prespecified analysis of the randomised trial DANFLU-2.

BACKGROUND: Frailty is a major risk factor for influenza-related complications and can influence vaccine effectiveness. We aimed to assess the relative vaccine effectiveness (rVE) of high-dose (HD-IIV) versus standard-dose inactivated influenza vaccine (SD-IIV) in older adults aged 65 years or older according to frailty risk. METHODS: This study was a prespecified analysis of DANFLU-2, an open-label, individually randomised trial, conducted in Denmark during three consecutive influenza seasons (2022-23, 2023-24, and 2024-25). Adults aged 65 years or older were randomised (1:1) to the HD-IIV or SD-IIV group. The primary endpoint was hospitalisation for influenza or pneumonia. Frailty was defined according to the validated Hospital Frailty Risk Score (HFRS) based on ICD-10 codes within 10 years before randomisation. Participants were stratified into three HFRS categories, namely low (<5 points), intermediate (5-15 points), and high (>15 points) frailty risk. The rVE of HD-IIV versus SD-IIV against the primary endpoint was assessed across prespecified HFRS categories and treating HFRS as a continuous variable. Pearson's chi-square test was used to compare safety events across frailty risk groups and randomisation groups. FINDINGS: Among 332&#x2009;438 randomised participants (mean age 73&#xb7;7 years [SD 5&#xb7;8]; 161&#x2009;538 [48&#xb7;6%] were female), 276&#x2009;173 (83&#xb7;1%) had low frailty risk, 52&#x2009;395 (15&#xb7;8%) had intermediate frailty risk, and 3861 (1&#xb7;2%) had high frailty risk. The primary endpoint of hospitalisation for influenza or pneumonia occurred in 1424 (0&#xb7;5%) of 276&#x2009;173 participants with low frailty risk, 761 (1&#xb7;5%) of 52&#x2009;395 with intermediate frailty risk, and 163 (4&#xb7;2%) of 3861 with high frailty risk (relative risk [RR] for intermediate vs low frailty risk 2&#xb7;8 [95% CI 2&#xb7;6-3&#xb7;1]; RR for high vs low frailty risk 8&#xb7;2 [7&#xb7;0-9&#xb7;6]). HFRS as a continuous variable significantly modified the effect of HD-IIV versus SD-IIV against the primary endpoint with higher rVE estimates with increasing HFRS (pinteraction=0&#xb7;020). The rVE was 0&#xb7;2% (95% CI -10&#xb7;8 to 10&#xb7;2) among those with low frailty risk, 13&#xb7;1% (-0&#xb7;4 to 24&#xb7;8) among those with intermediate frailty risk, and 19&#xb7;9% (-10&#xb7;3 to 42&#xb7;1) among those with high frailty risk. No significant interaction was observed when HFRS was assessed according to the prespecified categorical frailty groups (pinteraction=0&#xb7;17). The proportion of participants with at least one serious adverse event increased across frailty risk groups (13&#x2009;366 [4&#xb7;8%] of 275&#x2009;795 for low frailty risk, 5475 [10&#xb7;5%] of 52&#x2009;315 for intermediate frailty risk, and 777 [20&#xb7;2%] of 3850 for high frailty risk; p<0&#xb7;0001), with similar proportions of serious adverse events in the HD-IIV and SD-IIV groups for each frailty risk group. INTERPRETATION: Among adults aged 65 years or older in Denmark, frailty risk might modify the effects of HD-IIV versus SD-IIV against hospitalisation for influenza or pneumonia, with higher rVE estimates with increasing frailty risk. These findings might support considering high-dose influenza vaccines for frail older adults. However, effect modification was not evident when frailty was assessed using prespecified categorical subgroups, and subgroup-specific estimates were imprecise, with 95% CIs crossing the null. These results should be considered exploratory, warranting further investigation. FUNDING: The DANFLU-2 trial was funded by Sanofi.

Journal Article↗