The title gives the wrong impression, because there are two variables here you can't decode which one causes the problems. I'd say stress is the real problem.
Long-term stress and concomitant marijuana smoke exposure affect physiology, behavior and adult hippocampal neurogenesis
Kitti Rusznák1, Kata Csekő1,
Zsófia Varga1,
David Csabai1, Ágnes Bóna1,
Mátyás Mayer1,
Zsolt Kozma1,
Zsuzsanna Helyes1 and 
Boldizsar Czeh1* - 1University of Pécs, Hungary
Marijuana is a widely used recreational drug with increasing legalization worldwide for medical purposes. Most experimental studies use either synthetic or plant-derived cannabinoids to investigate the effect of cannabinoids on anxiety and cognitive functions. The aim of this study was to mimic real life situations where young people smoke cannabis regularly to relax from everyday stress. Therefore, we exposed young adult male NMRI mice to daily stress and concomitant marijuana smoke for two months and investigated the consequences on physiology, behavior and adult hippocampal neurogenesis. Animals were restrained for 6-hours/day for 5-days a week. During the stress, mice were exposed to cannabis smoke for 2×30min/day. We burned 2 “joints” (2×0.8g marijuana) per occasion in a whole body smoking chamber. Cannabinoid content of the smoke and urine samples was measured by HPLC and SFC-MS/MS. Body weight gain was recorded daily and we did unrestrained, whole body plethysmography to investigate pulmonary functions. The cognitive performance of the animals was evaluated by the novel object recognition and Y maze tests. Anxiety-related spontaneous locomotor activity and self-grooming were assessed in the open field test. Adult neurogenesis was quantified post mortem in the hippocampal dentate gyrus. The proliferative activity of the precursor cells was detected by the use of the exogenous marker 5-bromo-2'-deoxyuridine. Treatment effects on maturing neurons were studied by the examination of doublecortin-positive neurons. Both stress and cannabis exposure significantly reduced body weight gain. Cannabis smoke had no effect on pulmonary functions, but stress delayed the maturation of several lung functions. Neither stress, nor cannabis smoke affected the cognitive functioning of the animals. Results of the open field test revealed that cannabis had a mild anxiolytic effect and markedly increased self-grooming behavior. Stress blocked cell proliferation in the dentate gyrus, but cannabis had no effect on this parameter. Marijuana smoke however had a pronounced impact on doublecortin-positive neurons influencing their number, morphology and migration. In summary, we report here that long-term stress in combination with cannabis smoke exposure can alter several health-related measures, but the present experimental design could not reveal any interaction between these two treatment factors except for body weight gain.
Keywords:
Marijuana Smoking, Cannabis sativa, chronic stress, Hippocampus, adult neurogenesis, BrdU, doublecortin cells, Pulmonary Function, open field test, grooming behaviour, Body Weight, Novel object recognition
Received: 26 Apr 2018;
Accepted: 27 Jun 2018.
Edited by:
Carsten T. Wotjak, Max-Planck-Institut für Psychiatrie, Germany
Reviewed by:
Ismael Galve-Roperh, Complutense University of Madrid, Spain
Alline C. Campos, Universidade de São Paulo, Brazil
Copyright: © 2018 Rusznák, Csekő, Varga, Csabai, Bóna, Mayer, Kozma, Helyes and Czeh. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
MD, PhD. Boldizsar Czeh, University of Pécs, Pécs, Hungary, czeh.boldizsar@pte.hu
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