| 1. |
- Campeau, Audrey, et al.
(författare)
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Multiple sources and sinks of dissolved inorganic carbon across Swedish streams, refocusing the lens of stable C isotopes
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- It is well established that stream dissolved inorganic carbon (DIC) fluxes play a central role in the global C cycle, yet the sources of stream DIC remain to a large extent unresolved. Here, we explore large-scale patterns in delta C-13-DIC from streams across Sweden to separate and further quantify the sources and sinks of stream DIC. We found that stream DIC is governed by a variety of sources and sinks including biogenic and geogenic sources, CO2 evasion, as well as in-stream processes. Although soil respiration was the main source of DIC across all streams, a geogenic DIC influence was identified in the northernmost region. All streams were affected by various degrees of atmospheric CO2 evasion, but residual variance in delta C-13-DIC also indicated a significant influence of in-stream metabolism and anaerobic processes. Due to those multiple sources and sinks, we emphasize that simply quantifying aquatic DIC fluxes will not be sufficient to characterise their role in the global C cycle.
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| 2. |
- Coria, Jessica, 1979, et al.
(författare)
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The progress of GHG markets : opportunities and risks
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The climate negotiations at the COP15 in December 2009 did not produce a new international treaty with binding emissions commitments but the Copenhagen Accord for dealing with post-2012 climate change. Given the current climate negotiation process it is unlikely that we will see a global climate agreement soon on a global cap between all Convention members participating in a single carbon market. We may be more likely to see a stepwise process moving towards this scenario, most likely involving linkages between different national policy programs when it comes to mitigation as well as offsetting emissions. In such a process countries will offer commitments based on their domestic abilities, preferences and policies, norms and institutions. National and sub-national policies are thus likely to be the de-facto building blocks of nations' abilities to make and fulfill international commitments. However, also with multilateral mitigation programs without binding commitments, carbon markets will be needed as well as international authorities that support measurement, reporting and verification rules and the international registries. Such markets will necessarily be complicated and temporary in a world without an overarching binding agreement. There will be numerous tradeoffs between different kinds of second-best arrangements. The purpose of this report is to build knowledge about the effects of the development of regional and international carbon markets and the auxiliary technology agreements that might be needed. Among the topics we address are: the evolution and integration of carbon markets, the impacts of policy and technology cost uncertainty on the cost of meeting targets through a carbon market mechanism, the effect of banking, price floors and ceilings, institutional constraints and technological change in the further development of carbon markets and their links to other environmental policy instruments, and the potential of REDD-plus to encourage sustainable forest development and climate mitigation.
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| 3. |
- Löfgren, Magnus, 1979-
(författare)
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Behavioral effects of female sex steroid hormones : models of PMS and PMDD in Wistar rats
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background Animal models can be used to mimic human conditions of psychopathology, and also as pre-clinical models to evaluate candidate drugs. With hormonal treatment it is possible to produce behavior in the rat which corresponds to the mental symptoms of pre-menstrual syndrome (PMS), and pre-menstrual dysphoric disorder (PMDD). PMS affects 25-30 % of all women in fertile age and 3-8% are diagnosed with the more severe condition PMDD. The cardinal mental symptoms are; irritability, mood-swings, depression, anxiety, fatigue, insomnia, difficulties with concentration and memory and learning difficulties. The symptoms of PMS/PMDD occur in the luteal phase in conjunction with increasing concentrations of progesterone (P4) and P4-metabolites. In anovulatory cycles the symptoms are absent. The hormones which produce the monthly reoccurring negative symptoms on mood are foremost the neuroactive metabolites; allopregnanolone (ALLO) and tetrahydro-deoxycorticosterone (THDOC). ALLO is produced by the corpus luteum, but can also be synthesized in the brain, both ALLO and THDOC can also be released from the adrenal cortex during stress. These steroids are active on the inhibitory GABA neurotransmitter system through the GABAA receptor, and the effects are similar to that of alcohol and benzodiazepines. These steroids have strong sedative and hypnotic effects. A paradox is that some individuals seem to react with negative mood on sex steroids while all fertile women have the cyclical steroid changes during the menstrual cycle. Some individuals are more sensitive to neuroactive steroids with influences of personality, heritability and stress factors. Aims The thesis aims were to develop pre-clinical animal models of PMS/PMDD and to investigate induction of ALLO tolerance, individual sensitivity to neurosteroids and the interactions between chronic social stress and neurosteroids. Methods In these studies male and female Wistar rats were used to test steroid hormone effects on learning and memory and behaviors analogous to negative mood symptoms. This was accomplished through hormonal treatment and a subsequent withdrawal period from P4 (P4) + estradiol (E2) (PEWD), or ALLO. To assess tolerance, memory and learning in the Morris water maze (MWM) was studied. Anxiety-like behaviors were tested with the elevated plus maze (EPM), open field test (OFT), and the intruder test (IT). The EPM or OFT was used to classify the rats as high or low responders on risk-taking and explorative behavior (HR/LR). For social ranking order assessment the tube test (TT) and food competition test (FCT) were used. Chronic social stress was accomplished through co-habituation with two older rats (chronic subordination stress). In female rats the estrous cycle followed using staining of vaginal smears. Concentration of corticosterone (CORT) was measured by radio-immuno-assay (RIA). Results In the MWM ALLO pre-treatment produced tolerance to the acute negative ALLO effects. Both male and female rats showed behavioral correlations between the EPM and OFT tests, and correlations were also seen in CORT levels. Individuals with the stable trait of high risk-taking and explorative behavior (HR) were more sensitive to PEWD induction of anxiety-like behavior. These animals also showed decreased CORT levels during withdrawal. Chronic subordination stress enhanced the response to PEWD on measures of locomotor activity and social anxiety-like behavior. Conclusions It is possible to induce tolerance to the negative ALLO effects on learning and memory. The animal models of anxiety-like behavior show an individual PEWD response profile where HR rats are more sensitive. Exposure to chronic social stress enhanced the PEWD response. Hence there are both inherent and environmental factors behind the behavioral response to steroid hormones in rats.
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| 4. |
- Löfgren, Magnus, 1979-, et al.
(författare)
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Chronic subordination stress augments combined progesterone and estradiol withdrawal behavior
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Exposure to stress is a risk factor for developing pre-menstrual syndrome (PMS) and pre-menstrual dysphoric disorder (PMDD), and stress enhances the anxiogenic effect of female sex steroids in animals. This study examines the interaction between chronic subordination stress and withdrawal from progesterone (P4) and estradiol (E2) (PEWD) in producing behaviors analogous to anxiety and irritability in rats. At the start of the experiment, male Wistar rats were housed in triads consisting of one younger rat (~35 days) and two older rats (~50 days). The housing condition was aimed at producing chronic subordination stress in the younger animals. Chronic subordination stress was assessed by the elevated plus maze (EPM) and by corticosterone (CORT) analysis. A triad of three 35-day-old rats was used as age control. Social rank within the triads was determined using a food competition test (FCT) and the tube test (TT). The younger rats (subordinate) and the dominant rats were assigned to 10 days of treatment with 5 mg/kg progesterone combined with 10 µg/kg 17β estradiol. Twenty-four hours after the last injection, the subordinate and dominant animals were tested in the open-field test (OFT) and in the intruder test (IT). The IT consists of a 10-minute exposure to 3 unfamiliar rats. Chronic subordination stress reduced EPM open-arm time and altered the CORT response. It also made the subordinate animals more vulnerable to PEWD. The effects were increased locomotion in the OFT, increased defensive burying, and increased social anxiety in the intruder test (IT). Dominant animals did not react to PEWD. Thus, chronic subordination stress augments PEWD.
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| 5. |
- Löfgren, Magnus, 1979-, et al.
(författare)
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Progesterone withdrawal effects in the open field test can be predicted by elevated plus maze performance
- 2006
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Ingår i: Hormones and Behavior. - : Elsevier BV. - 0018-506X .- 1095-6867. ; 50:2, s. 208-215
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Tidskriftsartikel (refereegranskat)abstract
- Allopregnanolone (3alpha-hydroxy-5alpha-pregnane-20-one) is a ring-A-reduced metabolite of progesterone, which is naturally produced during the luteal phase of the menstrual cycle, during pregnancy and by stressful events. The steroid hormone inhibits neural functions through increased chloride ion flux through the GABAA receptor. The effects and subsequent withdrawal symptoms are similar to those caused by alcohol, benzodiazepines and barbiturates. This study examined the withdrawal effects of progesterone with regards to the influence of individual baseline exploration and risk taking. Rats were tested on the elevated plus maze (EPM) before hormonal treatment, in order to evaluate differences in risk taking and exploration of open and elevated areas. Treatment consisted of ten consecutive once a day progesterone or vehicle s.c. injections. On the last day of treatment, estradiol was injected in addition to progesterone, followed by a 24-h withdrawal before testing in the open field test (OF). Progesterone-treated rats showed a withdrawal effect of open area avoidance in the OF. The vehicle-treated control rats showed strong correlations between the EPM and OF parameters. This relationship was not found for the progesterone group at withdrawal. Rats with greater numbers of open arm entrance in the EPM pretest showed an increased sensitivity to progesterone withdrawal (PWD) compared to rats with low exploration and risk taking. The results indicate that the effects of PWD relate to individual exploration and risk taking. Furthermore, the possible analogy of PWD and PMS/PMDD in relation to individual traits is discussed.
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| 6. |
- Löfgren, Magnus, 1979-, et al.
(författare)
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The additive effect of allopregnanolone on ghrelin's orexigenic effect in rats
- 2019
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Ingår i: Neuropeptides. - : Elsevier BV. - 0143-4179 .- 1532-2785. ; 76
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Tidskriftsartikel (refereegranskat)abstract
- The progesterone metabolite, allopregnanolone (AlloP), is a GABA(A) receptor modulating steroid and is known to have orexigenic and pro-obesity effects. The neurobiological mechanisms underpinning these effects are most likely due to enhanced GABAergic signaling in the lateral arcuate nucleus (ARC) and medial paraventricular nucleus (PVN) of the hypothalamus. Inspired by the finding that GABAergic signaling is also important for the orexigenic effects of the circulating hormone, ghrelin, we sought to determine the extent to which AlloP (one of the most potent endogenous GABA(A)-receptor modulators) operates alongside ghrelin to enhance food intake. Male rats with ad libitum access to standard chow were injected intravenously with AlloP and/or ghrelin, alone or in combination. The intake of the standard chow was greater after AlloP 1 mg/kg together with ghrelin 30 mu g/kg than with 30 mu g/kg ghrelin alone. Food intake was also increased for the combined treatment of AlloP 0.5 mg/kg + ghrelin 10 mu g/kg, AlloP 1 mg/kg + ghrelin 10 mu g/kg, and AlloP 0.5 mg/kg + ghrelin 30 mu g/kg. There was no significant difference in food intake between the two ghrelin doses or between the two doses of AlloP and the vehicle. In electrophysiological studies, physiologically relevant concentrations of AlloP prolonged the current decay time of spontaneous inhibitory post-synaptic current of dissociated cells of the ARC and PVN. We conclude that AlloP enhances the hyperphagic effect of ghrelin, findings of potential relevance for the hyperphagia associated with the luteal phase of the reproductive cycle.
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| 7. |
- Löfgren, Magnus, 1979-, et al.
(författare)
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Withdrawal effects from progesterone and estradiol relate to individual risk-taking and explorative behavior in female rats
- 2009
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Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 96:1, s. 91-97
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Tidskriftsartikel (refereegranskat)abstract
- Withdrawal from progesterone and estradiol has been used as an animal model of premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD). In the clinical population individual sensitivity to sex steroid hormones, personality and heredity influence PMS/PMDD. Understanding the phenotypic risk factors of PMS/PMDD and drug development requires an animal model which incorporates individual steroid sensitivity. The main objective of this study was to investigate whether the individual trait of risk-taking and exploration influence the severity of PEWD in female rats. Thirty-two female Wistar rats in their diestrus phase were tested in the open field (OF) and divided into high responders (HR) and low responders (LR). Injections were given i.p. twice daily for 6 days, either 5 mg/kg progesterone combined with 10 mu g/kg 17 beta-estradiol, or vehicle (sesame oil). After a 24-hour withdrawal the animals were tested in the elevated plus maze (EPM). Blood samples for CORT analysis were collected after both behavioral tests. The HR rats withdrawn from progesterone and estradiol, spent less time on the EPM open arms and had lower CORT levels than the HR controls. The LR group showed no differences in EPM behavior and CORT levels during PEWD. The controls showed a stable trait of risk-taking and exploration. indicated by behavioral and CORT level correlations between the OF and EPM tests. These findings show that female rats with the trait of risk-taking and explorative behavior (HR) are more affected by PEWD.
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| 8. |
- Türkmen, Sahruh, et al.
(författare)
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Tolerance development to Morris water maze test impairments induced by acute allopregnanolone
- 2006
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Ingår i: Neuroscience. - : Elsevier Inc.. - 0306-4522 .- 1873-7544. ; 139:2, s. 651-659
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Tidskriftsartikel (refereegranskat)abstract
- The progesterone metabolite allopregnanolone, like benzodiazepines, reduces learning and impairs memory in rats. Both substances act as GABA agonists at the GABA-A receptor and impair the performance in the Morris water maze test. Women are during the menstrual cycle, pregnancy, and during hormone replacement therapy exposed to allopregnanolone or allopregnanolone-like substances for extended periods. Long-term benzodiazepine treatment can cause tolerance against benzodiazepine-induced learning impairments. In this study we evaluated whether a corresponding allopregnanolone tolerance develops in rats. Adult male Wistar rats were pretreated for 3 days with i.v. allopregnanolone injections (2 mg/kg) one or two times a day, or for 7 days with allopregnanolone injections 20 mg/kg intraperitoneally, twice a day. Thereafter the rats were tested in the Morris water maze for 5 days and compared with relevant controls. Rats pretreated with allopregnanolone twice a day had decreased escape latency, path length and thigmotaxis compared with the acute allopregnanolone group that was pretreated with vehicle. Pretreatment for 7 days resulted in learning of the platform position. However, the memory of the platform position was in these tolerant rats not as strong as in controls only given vehicle. Allopregnanolone treatment was therefore seen to induce a partial tolerance against acute allopregnanolone effects in the Morris water maze.
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