<p>Impulses coming from peripheries are modified in the spinal cord and transmitted to the brain. Several neurotransmitters have been involved in the processing of impulses in the spinal dorsal horn. Acetylcholine (ACh) is one of many neurotransmitters involved in the regulation of nociception in the spinal cord. In this study we investigated the role of nicotinic, muscarinic, serotonergic and GABA receptors in the regulation of spinal ACh release since these receptors are reported to be involved in spinal nociceptive processes.</p><p>Different receptor ligands were infused intraspinally via microdialysis and the spinal ACh release was measured by on-line HPLC. Receptor-ligand binding studies were performed with spinal cord homogenates as well as receptors expressed in cells.</p><p>In the first study, we found that nicotine and some of the nicotinic antagonists used increased ACh release suggesting that spinal ACh release is regulated by different nAChRs. Nicotine and nicotinic agonists may act on different types of receptors with different affinity to produce the observed net effect of increased ACh release. We propose the possibility of an involvement of three different nicotinic receptor subtypes in the regulation of spinal ACh release. </p><p>The effect of epibatidine, which is regarded as a nicotinic agonist, on muscarinic receptors was investigated in the second study. We propose that epibatidine, in μM concentrations, is a partial muscarinic receptor agonist that may interact with spinal muscarinic receptors to increase ACh release. The dual action on both nAChRs and mAChRs may explain the potent analgesic effect observed after intra-spinal epibatidine administration.</p><p>In the third study, we investigated the role of serotonin receptor involvement in ACh release control. The results suggest that only 5-HT_1A and 5-HT_2A receptors are involved in spinal ACh release. Considering current knowledge, the most probable location of 5-HT_2A receptors is on cholinergic neurones. On activation of the 5-HT_2A receptors the cellular excitability of cholinergic neurones is increased which results in an increasing ACh release. The 5-HT_1A receptors might be located on cell bodies of GABA neurones which inhibit the firing rate of the GABA neurones when activated by serotonin. </p><p>In the fourth study, we investigated the GABA receptor involvement in the regulation in spinal ACh release. We found that GABA_A receptors are tonically inhibiting spinal ACh release. The results further suggest that GABA_B receptors also are involved in the regulation of spinal ACh release. However, unlike GABA_A antagonists, GABA_B antagonists do not increase ACh release. This suggests that GABA_B receptors are not tonically regulating the spinal ACh release. </p>

<p>Animals show a great variety in physiological and behavioural responses to stressors. These responses are often bimodally distributed within populations and show consistency on an individual level over time and across situations, which in terrestrial vertebrates have been identified as proactive and reactive stress coping strategies. Proactive animals show lower cortisol responses, higher sympathetic activation and brain serotonergic activity compared to reactive animals. Behaviourally, proactive animals are more aggressive, more active in avoiding stressors, they form routines and show fewer cases of conditioned immobility compared to reactive animals. Our aim has been to reveal if such stress coping strategies exist in fish. Our results show that rainbow trout with high (HR) or low (LR) cortisol responses to stressors differs in sympathetic activation and brain serotonin turnover in the same manner as proactive and reactive mammals. HR fish showed less locomotor activity when reared in large groups (30 individuals) compared to LR fish. When reared in isolation there were no differences between HR and LR fish when exposed to stressors within a familiar environment. The adaption of a proactive coping style among reactive coping individuals when they are challenged within a familiar environment has previously been shown to be distinction between proactive and reactive coping mammals. However, when they were transferred to unfamiliar environments a behavioural difference between the two lines was observed indicating different stress coping strategies akin to those described in mammals. Finally, we observed a consistency over time in the cortisol response of an unselected line of rainbow trout. Fish from this line also demonstrated a correlation between behavioural responses to different stressors. However, there was no apparent connection between these behavioural responses and the cortisol response. Overall, the results of this thesis have strengthened the hypothesis that different stress coping strategies exist in teleost fish.</p>

<p>The overall aim of this thesis was to explore gene-environmental (G*E) interactions in relation to deviant behaviour among 200 Swedish adolescents, with a focus on criminality, alcohol consumption and depressive symptoms. Those behaviours have been extensively investigated in relation to both psychosocial and biological risk factors. The biological markers used were the monoamine oxidase (MAO-A) and serotonin transporter (5-HTTLPR) gene polymorphisms. </p><p>The main findings indicated a considerable gene-environment interaction in relation to all outcome variables studied. Individuals with the long/short variant of the 5HTTLPR gene, in combination with unfavourable family relations, both consumed more alcohol and had 12-14 times higher risks of being classified as high alcohol consumers.</p><p>The MAO-A gene showed a G*E interaction related to criminality. Among boys, the short allele predicted an increased risk for criminality, whereas among girls, it was the long allele, if they lived in multi-family houses and/or had been maltreated, assaulted or sexually abused. </p><p>A G*E interaction in relation to depressive symptoms among both boys and girls was determined. Girls carrying the short 5HTTLPR allele in combination with psychosocial stress, presented elevated depressive symptoms, whereas among boys, the long 5HTTLPR allele was a source of depressive symptoms. In both sexes, there was a G*E interaction of a psychosocial risk index. Girls were more affected by poor family relations and boys by multi-family housing and separated parents.</p><p>In conclusion, the MAO-A and 5HTTLPR genotypes, in interaction with psychosocial adversity, are related to different deviant behaviours among adolescents. The direct effects of the genotypes needed to be adjusted for the psychosocial factors, whereas the psychosocial factors had direct relation to the outcome measures. There is also an indication of a different pattern in G*E interaction between boys and girls and that different psychosocial factors affect boys and girls differently.</p>

Craving is thought to play a predominant role in the persistence of alcohol dependence, which seems to bear a substantial genetic component. Based on previous results highlighting the influence of serotonergic and dopaminergic nerotransmissions in both dependence and craving for alcohol, we investigated the impact of three specific polymorphisms on craving in male abstinent alcohol dependent patients. Our results show that alcohol craving may be influenced by genetic differences in alcohol dependent patients. There seems to be a dual serotonergic and dopaminergic modulation of craving. During acute withdrawal, desire to drink is predominantly influenced by the C1019 allele of the 5-HT1A receptor. Conversely, carrying the A1 allele of the DRD2 increases craving only when patients are no longer hospitalized and protected from drinking cues. Furthermore, we showed that craving partially influenced relapse and that the S allele of the 5-HTTpro, responsible for a 5-HT hypo-functioning, was significantly associated with relapse in abstinent alcohol dependent patients, possibly through intermediate phenotypes such as personality features or lack of behavioral inhibition. Our results may be useful in evaluating and developing novel pharmacogenetic approaches to treat alcohol dependence and one of its core symptoms, namely craving. Le craving semble jouer un rôle prédominant dans la persistance des comportements dalcoolisation et de rechute chez les sujets alcoolo-dépendants. Cette pathologie semble par ailleurs très nettement influencée par des facteurs dordre génétique. Sur base détudes préliminaires illustrant linfluence des neurotransmissions dopaminergique et sérotoninergique dans lalcoolo-dépendance et le craving pour lalcool, notre objectif a été dévaluer limpact de trois polymorphismes génétiques spécifiques sur le craving chez des patients masculins alcoolo-dépendant sevrés. Nos résultats montrent que le craving est bien influencé par des différences génétiques interindividuelles et quune modulation bimodale sérotoninergique et dopaminergique semble sexercer sur le craving pour lalcool. Pendant la phase aiguë du sevrage, lenvie de boire est nettement influencée par la présence de lallèle C du polymorphisme C-1019G du récepteur sérotoninergique 5-HT1A. A linverse, la présence de lallèle A1 du récepteur dopaminergique D2 ninfluence le craving quà distance du sevrage, lorsque les patients sont à nouveau dans leur milieu habituel et soumis à des stimuli déclanchant une envie de boire. De plus, nous avons pu montrer que le craving influençait partiellement la survenue dune rechute et que lallèle court du polymorphisme du promoteur du transporteur de la sérotonine (5-HTTpro) exerçait une influence significative sur la rechute, peut-être au travers de phénotypes intermédiaires de type traits de personnalité ou carence dinhibition comportementale. Ces résultats pourraient savérer utiles dans lévaluation et le développement de stratégies pharmacogénétiques destinées à traiter lalcoolo-dépendance et lun de symptômes les principaux : le craving.

Eukaryotic gene transcription plays a regulatory role in mammalian developmental processes. It has been shown that transcriptional control is an important mechanism for specification of neurotransmitter phenotypes. In the mammalian central nervous system, the transcription factor AP-2 family is one of the critical regulatory factors for neural gene expression and neuronal development. It has been shown that several genes in the monoaminergic systems have AP-2 binding sites in regulatory regions, suggesting a regulatory role of AP-2 also in the adult brain. Brainstem monoamines are implicated in the expression of personality traits and imbalances in these systems may give rise to psychiatric disorders. The gene encoding AP-2β includes a polymorphic region consisting of a tetranucleotide repeat of [CAAA]4-5 in intron 2. Studies on AP-2β genotype in relation to personality and platelet MAO activity, a trait-dependant marker for personality, are presented in this thesis. Furthermore, correlations between brainstem levels of AP-2α and AP-2β and monoamine turnover in projection areas in rat forebrain are reported. These results strengthen the notion that the AP-2 family is important regulators of the monoaminergic systems in the adult brain. Furthermore, two studies are presented in this thesis with analyses indicating a role for AP-2 in the molecular mechanism of antidepressant drugs. Altogether, this thesis presents data supporting our notion that the transcription factor AP-2 family is involved in the regulation of the monoaminergic systems both pre- and postnatally, and, therefore, might be involved in the pathophysiology of neuropsychiatric disorders.

The CNS monoaminergic systems are considered as the head engine regulating neuropsychiatric functions and personality. Transcription factor AP-2 is known to be essential for the development of the brainstem including the monoaminergic nuclei, and has the ability to regulate many genes in the monoaminergic systems. The ability of transcription factors to regulate specific gene expression, has lately made them hot candidates as drug targets. In this thesis, results indicating a role of AP-2 in the molecular effects of the antidepressant drugs citalopram and phenelzine, are presented. A polymorphism in the second intron of the gene encoding AP-2ß has previously been associated with anxiety-related personality traits as estimated by the Karolinska Scales of Personality (KSP). In this thesis, results confirming this association, gained by using a larger material and several different personality scales, are presented. Furthermore, data is presented showing an association between the activity of platelet monoamine oxidase, a trait-dependent marker for personality, and the genotype of the AP-2ß intron 2 polymorphism. The functional importance of the AP-2ß intron 2 polymorphism has not yet been elucidated. Included in this thesis are results showing that the AP-2ß intron 2 polymorphism is not in linkage disequilibrium with the only other described polymorphism in the AP-2ß gene, i.e. in the AP-2ß promoter (-67 G/A). Introns have in several studies been shown to include binding sites for regulatory proteins, and thus, to be important in transcriptional regulation. Results are presented demonstrating that one human brain nuclear protein binds only to the long variant of the AP-2ß intron 2 polymorphism. If this protein is involved in the regulation of the AP-2ß gene, it would affect the expression levels of the AP-2ß protein. In general, this thesis further establishes the role of transcription factor AP-2 as a regulatory factor of importance for personality and monoaminergic functions.

Impulses coming from peripheries are modified in the spinal cord and transmitted to the brain. Several neurotransmitters have been involved in the processing of impulses in the spinal dorsal horn. Acetylcholine (ACh) is one of many neurotransmitters involved in the regulation of nociception in the spinal cord. In this study we investigated the role of nicotinic, muscarinic, serotonergic and GABA receptors in the regulation of spinal ACh release since these receptors are reported to be involved in spinal nociceptive processes. Different receptor ligands were infused intraspinally via microdialysis and the spinal ACh release was measured by on-line HPLC. Receptor-ligand binding studies were performed with spinal cord homogenates as well as receptors expressed in cells. In the first study, we found that nicotine and some of the nicotinic antagonists used increased ACh release suggesting that spinal ACh release is regulated by different nAChRs. Nicotine and nicotinic agonists may act on different types of receptors with different affinity to produce the observed net effect of increased ACh release. We propose the possibility of an involvement of three different nicotinic receptor subtypes in the regulation of spinal ACh release. The effect of epibatidine, which is regarded as a nicotinic agonist, on muscarinic receptors was investigated in the second study. We propose that epibatidine, in μM concentrations, is a partial muscarinic receptor agonist that may interact with spinal muscarinic receptors to increase ACh release. The dual action on both nAChRs and mAChRs may explain the potent analgesic effect observed after intra-spinal epibatidine administration. In the third study, we investigated the role of serotonin receptor involvement in ACh release control. The results suggest that only 5-HT1A and 5-HT2A receptors are involved in spinal ACh release. Considering current knowledge, the most probable location of 5-HT2A receptors is on cholinergic neurones. On activation of the 5-HT2A receptors the cellular excitability of cholinergic neurones is increased which results in an increasing ACh release. The 5-HT1A receptors might be located on cell bodies of GABA neurones which inhibit the firing rate of the GABA neurones when activated by serotonin. In the fourth study, we investigated the GABA receptor involvement in the regulation in spinal ACh release. We found that GABAA receptors are tonically inhibiting spinal ACh release. The results further suggest that GABAB receptors also are involved in the regulation of spinal ACh release. However, unlike GABAA antagonists, GABAB antagonists do not increase ACh release. This suggests that GABAB receptors are not tonically regulating the spinal ACh release.

Supratherapeutic doses of anabolic androgenic steroids (AASs) are administered, not only as performance-enhancing drugs in the world of sports, but also in order to modify behaviour. AAS abusers are at risk of developing serious physical and psychological side effects such as dependence and aggressive behaviour. The aim of this thesis was to investigate the impact of supratherapeutic doses of nandrolone decanoate after subchronic administration on dopamine and serotonin pathways involved in drug dependence and aggression, in the male rat brain. Adult male Sprague-Dawley rats received intramuscular injections of nandrolone decanoate (3 or 15 mg/kg) or vehicle once daily for 14 days. Nandrolone decanoate pre-exposure abolished the effect of amphetamine on the 3,4-dihydroxyphenylacetic acid (DOPAC) tissue level in the hypothalamus and on the DOPAC/dopamine ratio in the hypothalamus and the hippocampus. A significant decrease of the basal extracellular DOPAC and homovanillic acid (HVA) levels could be detected in the nucleus accumbens, which remained low during the first hour following the amphetamine challenge. Nandrolone decanoate significantly reduced the activity of both monoamine oxidase A and B (MAO-A and -B) in the caudate putamen and amygdala. The gene transcript levels of MAO-B, and the dopamine D1 and D4 receptors were altered in limbic regions. No changes in transcriptional levels could be detected among the serotonin receptor genes examined. However, the density of the serotonin transporter protein was elevated in a range of aggression-related brain regions. Taken together, subchronic administration of nandrolone decanoate causes dopaminergic and serotonergic dysregulations in distinct brain regions. These areas of the brain are involved in the development of drug dependence and expression of impulsive and aggressive behaviours. These results may contribute to explain some of the behavioural changes often reported in AAS abusers, such as polydrug use and impaired impulse control.

Several studies suggest profound effects on mood and cognition by neuroactive steroids. Estrogen alone or in combination with antidepressant drugs affecting the serotonin system has been used to treat mood disorders. On the other hand, progesterone is related to negative effects on mood and memory. A major part of the progesterone effects on the brain can be mediated by its metabolite allopregnanolone, which is also de novo synthesized in the brain, and affects the GABAA receptors. It would be of great importance to find a substance that antagonize allopregnanolone adverse effects. To investigate how long term supplementation of estradiol and progesterone, resembling postmenopausal hormone replacement therapy, affects serotonin receptors in different brain areas important for mood and memory functions, we used ovariectomized female rats. After 2 weeks of supplementation with 17β-estradiol alone or in combination with progesterone, or placebo pellets, estradiol alone decreases but estradiol supplemented together with progesterone increases 5HT1A mRNA expression in the hippocampus. Estradiol decreases the 5HT2C receptor gene expression, while estradiol in combination with progesterone increases the 5HT2A mRNA expression in the ventral hippocampus. Thus, estradiol alone has opposite effects compared to the estradiol/progesterone combination. To detect if acute tolerance develops to allopregnanolone, an EEG method was used where male rats by continuous allopregnanolone infusion were kept on anesthesia level of the silent second (SS). After different time intervals (first SS, 30 min or 90 min of anesthesia) several GABAA receptor subunit mRNAs were measured for detecting if changed expression of any GABAA receptor subunits is involved in development of acute tolerance. There is development of acute tolerance to allopregnanolone and brain regions of importance are hippocampus, thalamus and hypothalamus. The GABAA receptor alpha4 subunit in thalamus and alpha2 subunit in the dorsal hippocampus are related to development of acute tolerance. For assessing allopregnanolone behavioral effects, we studied how this neurosteroid affects spatial learning in the Morris water maze task Allopregnanolone inhibits spatial learning short after the injection and shows a specific behavioral pattern with swimming close to the pool wall. The steroid UC1011 can inhibit the increase in chloride ion uptake induced by allopregnanolone. UC1011 decreases allopregnanoloneinduced impairment of spatial learning in the water maze, as well as the specific behavioral swim pattern. In conclusion, the present work demonstrates that neuroactive steroids affect the 5HT and GABA systems in a brain region specific way. GABAA receptor subunit changes in hippocampus and thalamus are related to acute allopregnanolone tolerance. Allopregnanolone induces cognitive deficits, like spatial learning impairment and UC1011 can inhibit allopregnanolone-induced effects in vitro and in vivo. Key words: Estradiol, progesterone, HRT, allopregnanolone, UC1011, serotonin receptor, GABAA receptor, mRNA, Morris water maze, silent second, tolerance.

The overall aim of this thesis was to explore gene-environmental (G*E) interactions in relation to deviant behaviour among 200 Swedish adolescents, with a focus on criminality, alcohol consumption and depressive symptoms. Those behaviours have been extensively investigated in relation to both psychosocial and biological risk factors. The biological markers used were the monoamine oxidase (MAO-A) and serotonin transporter (5-HTTLPR) gene polymorphisms. The main findings indicated a considerable gene-environment interaction in relation to all outcome variables studied. Individuals with the long/short variant of the 5HTTLPR gene, in combination with unfavourable family relations, both consumed more alcohol and had 12-14 times higher risks of being classified as high alcohol consumers. The MAO-A gene showed a G*E interaction related to criminality. Among boys, the short allele predicted an increased risk for criminality, whereas among girls, it was the long allele, if they lived in multi-family houses and/or had been maltreated, assaulted or sexually abused. A G*E interaction in relation to depressive symptoms among both boys and girls was determined. Girls carrying the short 5HTTLPR allele in combination with psychosocial stress, presented elevated depressive symptoms, whereas among boys, the long 5HTTLPR allele was a source of depressive symptoms. In both sexes, there was a G*E interaction of a psychosocial risk index. Girls were more affected by poor family relations and boys by multi-family housing and separated parents. In conclusion, the MAO-A and 5HTTLPR genotypes, in interaction with psychosocial adversity, are related to different deviant behaviours among adolescents. The direct effects of the genotypes needed to be adjusted for the psychosocial factors, whereas the psychosocial factors had direct relation to the outcome measures. There is also an indication of a different pattern in G*E interaction between boys and girls and that different psychosocial factors affect boys and girls differently.