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  • 1.
    Bengtsson, Sara
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Gouissem, Samira
    Umecrine AB.
    Johansson, Maja
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Wang, Mingde
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Chronic allopregnanolone elevation cause altered plaque production in Swe/PS1 miceManuscript (preprint) (Other academic)
    Abstract [en]

    Abstract. We have previously shown that chronic elevation of the neurosteroid allopregnanolone caused learning dysfunction and increased levels of soluble Aβ in the Swe/PS1 mouse model. The mechanism behind these findings is however unknown. We further investigated the brain tissue of these mice to identify any effects on congophilic plaque burden, Aβ42-specific plaque burden and synaptic function. We found a significant reduction in the average size of the congophilic core of neuritic plaques after chronic allopregnanolone treatment compared to vehicle. This seems to be caused by an altered plaque production, leading to more abundant, but smaller neuritic plaques. We may also have detected a decrease in the amount of synaptophysin, and thus synaptic function among the same mice. However, the long interval between the end of treatment and tissue collection possibly allowed time for recovery and only minor differences were noted. We found that the natural relationship between levels of insoluble Aβ, congophilic and Aβ42-specific plaque load was disrupted after chronically elevated allopregnanolone levels. Furthermore, the levels of syn-aptophysin and insoluble Aβ became more important in the relationship to learning and memory. The causality of these factors is still unknown and further studies are required to fully understand the effect of neurosteroids on AD development.

  • 2.
    Birzniece, Vita
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Johansson, Inga-Maj
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lindblad, Charlotte
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Löfgren, Magnus
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Olsson, Tommy
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Ragagnin, Gianna
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Taube, Magdalena
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Turkmen, Sahruh
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Wahlström, Göran
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Pharmacology.
    Wang, Ming-De
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Wihlbäck, Anna-Carin
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Zhu, Di
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Neuroactive steroid effects on cognitive functions with a focus on the serotonin and GABA systems.2006In: Brain Research Reviews, ISSN 0165-0173, E-ISSN 1872-6321, Vol. 51, no 2, p. 212-239Article in journal (Refereed)
  • 3.
    Bäckström, Torbjörn
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Andersson, Agneta
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Andreén, Lotta
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Birzniece, Vita
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bixo, Marie
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Björn, Inger
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Haage, David
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Isaksson, Monica
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Johansson, Inga-Maj
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lindblad, Charlott
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Nyberg, Sigrid
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Ödmark, Inga-Stina
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Strömberg, Jessica
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Sundström-Poromaa, Inger
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Turkmen, Sahruh
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Wahlström, Göran
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Wang, Mingde
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Wihlbäck, Anna-Carin
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Zhu, Di
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Zingmark, Elisabeth
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Pathogenesis in menstrual cycle-linked CNS disorders.2003In: Annals of the New York Academy of Sciences, ISSN 0077-8923, E-ISSN 1749-6632, Vol. 1007, p. 42-53Article, review/survey (Other academic)
  • 4.
    Gunnarsson, David
    et al.
    Umeå University, Faculty of Science and Technology, Molecular Biology (Faculty of Science and Technology).
    Nordberg, Gunnar
    Umeå University, Faculty of Medicine, Public Health and Clinical Medicine.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Clinical Sciences.
    Selstam, Gunnar
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Cadmium-induced decrement of the LH receptor expression and cAMP levels in the testis of rats2003In: Toxicology, ISSN 0300-483X, E-ISSN 1879-3185, Vol. 183, no (1-3), p. 57-63Article in journal (Refereed)
    Abstract [en]

    Cadmium (Cd) is a widespread environmental pollutant, characterized by its ability to affect various organs. Adverse effect of Cd on the testis including decreased testosterone production are well-known phenomena, but the cellular events explaining these effects have not yet been established. In the present study the initial steps of gonadotropin mediated testosterone biosynthesis were examined in vivo in rats, in relation to Cd dose and time after injection. In the dose–response experiment Male Sprague–Dawley rats received a single subcutaneous (sc) injection of CdCl2 (1, 5 or 10 μmol/kg body weight) and were sacrificed 48 h after injection. A statistically significant decrease in luteinizing hormone (LH) receptor mRNA level in the testicular tissue was demonstrated at the highest dose (10 μmol/kg). In the temporal–response experiment rats were given 10 μmol/kg of CdCl2 sc and sacrificed 0.48, 4.8, 48 or 144 h after injection. LH receptor mRNA levels as well as cyclic adenosine monophosphate (cAMP) levels were found to be significantly lowered at 48 and 144 h. These observations of the mechanisms whereby Cd exerts its effect on the initial steps of testosterone biosynthesis are the first from in vivo experiments.

  • 5.
    Kask, Kristiina
    et al.
    Department Women's and Children's Health, Uppsala University, Uppsala, Sweden.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Sundström Poromaa, Inger
    Department Women's and Children's Health, Uppsala University, Uppsala, Sweden.
    Allopregnanolone has no effect on startle response and prepulse inhibition of startle response in patients with premenstrual dysphoric disorder or healthy controls2009In: Pharmacology, Biochemistry and Behavior, ISSN 0091-3057, E-ISSN 1873-5177, Vol. 92, no 4, p. 608-613Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Allopregnanolone is an endogenous neuroactive steroid which, through the binding to the GABA(A) receptor, enhances inhibitory neurotransmission and exerts anxiolytic, sedative and antiepileptic effects. Following acute administration, allopregnanolone reliably acts as an anxiolytic compound. The primary aim of this study was to investigate if allopregnanolone, administered to healthy women and women with premenstrual dysphoric disorder (PMDD), would have an anxiolytic effect, expressed as a decreased startle response. MATERIALS AND METHODS: Sixteen PMDD patients and twelve healthy controls completed the study. The participants were scheduled for the startle tests twice in the luteal phase. During the test sessions an intravenous allopregnanolone and placebo bolus injection was administered in double-blinded, randomized order at intervals of 48 h. Following the allopregnanolone/placebo injections startle response and prepulse inhibition of startle response (PPI) were assessed by electromyography. RESULTS: Following the intravenous allopregnanolone administration the serum concentrations of allopregnanolone increased to 50-70 nmol/l, corresponding to levels that are seen during pregnancy. The obtained serum concentrations of allopregnanolone were significantly lower in PMDD patients than among the healthy controls, p<0.05. The allopregnanolone injection resulted in significant increases of self-rated sedation in both groups, p<0.01. Allopregnanolone did not induce any changes in startle response or prepulse inhibition of startle response in comparison to placebo. No differences in allopregnanolone-induced changes in startle response or PPI could be detected between PMDD patients and controls subjects. CONCLUSION: Startle response and PPI were unaffected by acute intravenous administration of allopregnanolone in PMDD patients and healthy controls.

  • 6.
    Lundgren, Per
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Strömberg, Jessica
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Wang, Mingde
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Allopregnanolone-stimulated GABA-mediated chloride ion flux is inhibited by 3beta-hydroxy-5alpha-pregnane-20-one (isoallopregnanolone)2003In: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 982, no 1, p. 45-53Article in journal (Refereed)
  • 7.
    Löfgren, Magnus
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Johansson, Inga-Maj
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Meyerson, Bengt
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Progesterone withdrawal effects in the open field test can be predicted by elevated plus maze performance2006In: Hormones and Behavior, ISSN 0018-506X, E-ISSN 1095-6867, Vol. 50, no 2, p. 208-215Article in journal (Refereed)
    Abstract [en]

    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.

  • 8.
    Strömberg, Jessica
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Rapid non-genomic effect of glucocorticoid metabolites and neurosteroids on the gamma-aminobutyric acid-A receptor2005In: European Journal of Neuroscience, ISSN 0953-816X, E-ISSN 1460-9568, Vol. 21, no 8, p. 2083-2088Article in journal (Other academic)
  • 9.
    Strömberg, Jessica
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Haage, David
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Taube, Magdalena
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Neurosteroid modulation of allopregnanolone and GABA effect on the GABA-A receptor2006In: Neuroscience, ISSN 0306-4522, E-ISSN 1873-7544, Vol. 143, no 1, p. 73-81Article in journal (Refereed)
  • 10.
    Strömberg, Jessica
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Taube, Magdalena
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Wang, Mingde
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Haage, David
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    The effect of the neuroactive steroid 5β-pregnane-3β, 20(R)-diol on the time course of GABA evoked currents is different to that of pregnenolone sulphate2009In: European Journal of Pharmacology, ISSN 0014-2999, E-ISSN 1879-0712, Vol. 605, no 1-3, p. 78-86Article in journal (Refereed)
    Abstract [en]

    The endogenous progesterone metabolite allopregnanolone has a number of properties including anesthetic, sedative, antiepileptic, anxiolytic, impaired memory function and negative mood symptoms. Allopregnanolone is a potent positive GABA(A) receptor function modulators. In contrast, 3beta-hydroxy-steroids (3beta-steroids) usually modulate the GABA(A) receptor negatively. They have attracted some interest for their possible use as therapeutic agents that could counteract the negative symptoms induced by allopregnanolone. Two hypotheses for the action of 3beta-steroids have been proposed: 1) 3beta-steroids act in a similar way to pregnenolone sulphate, which non-competitively reduces GABA(A) receptor activity. 2) 3beta-steroids specifically antagonize the effect of allopregnanolone. We have therefore tried to clarify this issue by comparing the effect of pregnenolone sulphate and 5beta-pregnane-3beta, 20(R)-diol on the GABA-evoked currents by the patch clamp technique on neurons from the medial preoptic nucleus. Both pregnenolone sulphate and 5beta-pregnane-3beta, 20(R)-diol increase the desensitization rate of the current response evoked by a 2 s GABA application. However, their effects on other parameters of the GABA evoked currents differed in degree and sometimes even in direction. The actions of pregnenolone sulphate and 5beta-pregnane-3beta, 20(R)-diol were not altered in the presence of allopregnanolone, which indicates that they do not directly interact with allopregnanolone. In addition, when 5beta-pregnane-3beta, 20(R)-diol was tested on spontaneous inhibitory postsynaptic currents (sIPSCs), it dramatically reduced the allopregnanolone-induced prolongation of the decay time constant but it had no effect on the decay under control conditions. In conclusion, the effect of 5beta-pregnane-3beta, 20(R)-diol on GABA-evoked currents is different to that of pregnenolone sulphate in medial preoptic nucleus neurons.

  • 11.
    Strömberg, Jessica
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Taube, Magdalena
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Wang, Mingde
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Haage, David
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    The neuroactive steroid 5beta-pregnane-3beta, 20(R)-diol alters the kinetic properties of the GABA-A receptor differently from pregnenolone-sulfateManuscript (Other academic)
  • 12.
    Turkmen, Sahruh
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Birzniece, Vita
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Zingmark, Elisabeth
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Johansson, Inga-Maj
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    3beta-20beta-dihydroxy-5alpha-pregnane (UC1011) antagonism of the GABA potentiation and the learning impairment induced in rats by allopregnanolone.2004In: European Journal of Neuroscience, ISSN 0953-816X, E-ISSN 1460-9568, Vol. 20, no 6, p. 1604-1612Article in journal (Refereed)
    Abstract [en]

    Allopregnanolone is a progesterone metabolite and GABA-A receptor modulator with benzodiazepine like effects, including decreased learning and memory. In vitro 3beta-hydroxypregnane steroids antagonize allopregnanolone-induced effects, but no antagonism has been shown in vivo. Our purpose was to evaluate 3beta-20beta-dihydroxy-5alpha-pregnane (UC1011) as a blocker of allopregnanolone-induced effects in vivo and in vitro in rats. We tested adult male Wistar rats in the Morris water maze 8 min after daily injections (i.v.) of allopregnanolone 2 mg/kg (n = 21); allopregnanolone : UC1011 2 : 6 (n = 7), 2 : 8 (n = 7), 2 : 20 (n = 14) mg/kg; UC1011 20 mg/kg (n = 14); or vehicle (10% 2-hydroxypropyl-beta-cyclodextrin, n = 4). Studies of chloride ion uptake into cortical and hippocampal membrane preparations were performed. The latency to find the hidden platform was still high in the allopregnanolone-injected group on day 6. Day 3-6 rats injected with allopregnanolone and UC1011 (2 : 20 mg/kg) had lower latency (P < 0.05), compared to the allopregnanolone-injected group. The group that only received UC1011 learned the location of the platform as fast as the controls. There was no significant difference in swim speed between groups. The time spent swimming close to the pool wall was in the allopregnanolone : UC1011 group (2 : 20 mg/kg) significantly decreased (P < 0.05, day 3-6), compared to the allopregnanolone-injected group. The increased chloride ion uptake induced by increasing dosage of allopregnanolone in the presence of 10 micro m GABA was significantly decreased with UC1011 (P < 0.01), in both cortical and hippocampal homogenates. In conclusion, UC1011 can via antagonism at the GABA-A receptor reduce the negative allopregnanolone effect on learning in the water maze.

  • 13.
    Wang, Ming-De
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Borra, Vijaya Bhaskar
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Strömberg, Jessica
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Haage, David
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Neurosteroids 3beta, 20 (R/S)-pregnandiols decrease offset rate of the GABA-site activation at the recombinant GABA(A) receptor.2008In: Eur J Pharmacol, ISSN 0014-2999, Vol. 586, no 1-3, p. 67-73Article in journal (Refereed)
  • 14.
    Öfverman, Charlotte
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Strömberg, Jessica
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Birzniece, Vita
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Turkmen, Sahruh
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Hill, Martin
    Institute of Endocrinology, Nároní trída 8, CZ 116 94, Prague, Czech Republic.
    Lundgren, Per
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Bäckström, Torbjörn
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    Johansson, Inga-Maj
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Obstetrics and Gynaecology.
    The progesterone metabolite isoallopregnanolone is a subunit-selective antagonist of the GABA-A receptorManuscript (preprint) (Other academic)
    Abstract [en]

     Allopregnanolone is a progesterone metabolite that can negatively affect learning and induce anaesthesia in rats. It also impairs episodic memory in women. Allopregnanolone levels are elevated during the luteal phase of the menstrual cycle, during pregnancy, and during stress. Allopregnanolone is a strong positive modulator of the GABAA receptor. The subunit composition of the GABAA receptor is of importance for effects of modulators, and GABAA receptors including the α5-subunit are of significance for learning, while receptors with other subunits are involved in e.g. anesthesia. Isoallopregnanolone, a natural 3β-epimer of allopregnanolone, has been shown to antagonize allopregnanolone-induced anesthesia in rats.

    We tried to block the allopregnanolone-induced impairment of learning in rats in the Morris water maze test, using isoallopregnanolone (4–32 mg/kg). We also determined steroid concentrations in blood and brain tissue, and with whole-cell patch clamp we studied the effects of isoallopregnanolone and tetrahydrodeoxycorticosterone (a neurosteroid similar to allopregnanolone) on HEK-293 cells expressing the human α5β2γ2L GABAA receptor.

    Isoallopregnanolone did not block the negative effects of allopregnanolone (2 mg/kg) in the Morris water maze test. Our presumed antagonist actually had an agonistic effect on the tetrahydrodeoxycorticosterone-mediated potentiation of the GABA effect on the α5β2γ2L GABAA receptor. The baseline shift induced by tetrahydrodeoxycorticosterone alone was not reversed by isoallopregnanolone. A bidirectional epimerisation between allopregnanolone and isoallopregnanolone was also identified in the rat.

    The lack of antagonistic effect at the α5β2γ2L GABAA receptor together with the epimerisation of isoallopregnanolone to allopregnanolone would probably explain the lack of effect of our proposed antagonist on the allopregnanolone-induced impairment of learning 

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