21.
22.
Ploj, Karolina, et al.
(författare)
Effects of neonatal handling on nociceptin/orphanin FQ and opioid peptide levels in female rats
2001
Ingår i: Pharmacology, Biochemistry and Behavior. - 0091-3057 .- 1873-5177. ; 69:1-2, s. 173-179
Tidskriftsartikel (refereegranskat) abstract
Animals exposed to short periods of handling during the critical period of development, i.e., the first 21 days of life in rats, show attenuated neuroendocrine responses to stress in adult life. We have previously reported long-term changes in brain dynorphin (DYN) peptide levels in male Sprague-Dawley rats after neonatal handling. The purpose of this study was to investigate whether neonatal handling, 15-min individual separation from the mother during postnatal days 1-21, can induce long-term changes in DYNB, Met-enkephalin Arg(6)Phe(7) (MEAP) and nociceptin/orphanin FQ (N/OFQ) immunoreactive (ir) levels in female Sprague-Dawley rats. The peptides were measured in brain and pituitary gland 2 months after the handling procedure. The results reveal that handled (H) rats had increased ir levels of N/OFQ, DYNB and MEAP in the periaqueductal gray (PAG) as compared to nonhandled (NH) controls. Furthermore, H rats had decreased ir levels of DYNB in the frontal cortex and in the amygdala. In contrast to previous findings in male rats, DYNB levels were unaffected in areas related to the hypothalamo - pituitary - adrenal (HPA)-axis. The results indicate that a manipulation early in life can induce persistent neurochemical changes in the N/OFQ and opioid peptide system in female Sprague-Dawley rats.
23.
Prusis, Peteris
(författare)
Modelling of melanocortin receptors and their ligands
2001
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Five subtypes of melanocortin receptors (MC1-MC5R) mediate a wide range of physiological actions, including control of skin tanning, inflammation and food intake. The natural ligands for these receptors are the melanocortins, which are linear peptides 11 to 39 amino acids long. The aim of this study was to investigate the interactions between melanocortin receptors and melanocortins using computational modeling tools.Two three-dimensional (3D) models of the MC, receptor were created using homology modeling. The first model was based on the 3D structure of bacteriorhodopsin, while the second was based on the two-dimensional map of rhodopsin. Cyclic analogues of the melanocortins containing the core sequence motif HFRW, common to all melanocortins, could be docked into the receptor models. According to these models, the ligand binding pocket was located between the receptors' first, second, third, sixth and seventh transmembrane regions. The rhodopsin based model indicated that the His residue of the melanocortin's core sequence showed only minor interactions with the receptor. Synthesis and receptor binding of cyclic peptide analogues lacking this His residue gave experimental support for the modeling results. Support for the 30 models had also been obtained in binding studies using chimeric MC1MC3 receptors. However, the visual analysis of this binding data was subjective. A novel objective approach was developed for the analysis of data of chimeric proteins interacting with peptides. The new approach, which is based on the use of multivariate analysis tools, such as PLS, gave a very exact picture for the interactions of melanocortin receptors with their ligands. Moreover, the results of the 3D modeling and PLS modeling agreed well. The novel method seems applicable for the analysis of almost any interactions between several target and ligand molecules.
24.
Ravald, Linus, et al.
(författare)
Theoretical study of the accuracy of the elution by characteristic points method for bi-Langmuir isotherms
2001
Ingår i: Journal of Chromatography A. - 0021-9673 .- 1873-3778. ; 908:1-2, s. 111-130
Tidskriftsartikel (refereegranskat) abstract
The bi-Langmuir equation has recently been proven essential to describe chiral chromatographic surfaces and we therefore investigated the accuracy of the elution by characteristic points method (ECP) for estimation of bi-Langmuir isotherm parameters. The ECP calculations was done on elution profiles generated by the equilibrium-dispersive model of chromatography for five different sets of bi-Langmuir parameters. The ECP method generates two different errors; (i) the error of the ECP calculated isotherm and (ii) the model error of the fitting to the ECP isotherm. Both errors decreased with increasing column efficiency. Moreover, the model error was strongly affected by the weight of the bi-Langmuir function fitted. For some bi-Langmuir compositions the error of the ECP calculated isotherm is too large even at high column efficiencies. Guidelines will be given on surface types to be avoided and on column efficiencies and loading factors required for adequate parameter estimations with ECP.
25.
Ringbom, Therese, et al.
(författare)
Cox-2 inhibitory effects of naturally occurring and modified fatty acids
2001
Ingår i: Journal of natural products (Print). - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 64:6, s. 745-749
Tidskriftsartikel (refereegranskat) abstract
In the search for new cyclooxygenase-2 (COX-2) selective inhibitors, the inhibitory effects of naturally occurring fatty acids and some of their structural derivatives on COX-2-catalyzed prostaglandin biosynthesis were investigated. Among these fatty acids, linoleic acid (LA), alpha-linolenic acid (alpha-LNA), myristic acid, and palmitic acid were isolated from a CH(2)Cl(2) extract of the plant Plantago major by bioassay-guided fractionation. Inhibitory effects of other natural, structurally related fatty acids were also investigated: stearic acid, oleic acid, pentadecanoic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Further, the inhibitory effects of these compounds on COX-2- and COX-1-catalyzed prostaglandin biosynthesis was compared with the inhibition of some synthesized analogues of EPA and DHA with ether or thioether functions. The most potent COX-2-catalyzed prostaglandin biosynthesis inhibitor was all-(Z)-5-thia-8,11,14,17-eicosatetraenoic acid (2), followed by EPA, DHA, alpha-LNA, LA, (7E,11Z,14Z,17Z)-5-thiaeicosa-7,11,14,17-tetraenoic acid, all-(Z)-3-thia-6,9,12,15-octadecatetraenoic acid, and (5E,9Z,12Z,15Z,18Z)-3-oxaheneicosa-5,9,12,15,18-pentaenoic acid, with IC(50) values ranging from 3.9 to180 microM. The modified compound 2 and alpha-LNA were most selective toward COX-2, with COX-2/COX-1 ratios of 0.2 and 0.1, respectively. This study shows that several of the natural fatty acids as well as all of the semisynthetic thioether-containing fatty acids inhibited COX-2-catalyzed prostaglandin biosynthesis, where alpha-LNA and compound 2 showed selectivity toward COX-2.
26.
Rosenborg, Johan
(författare)
Clinical-Pharmacokinetic Aspects of Prolonged Effect Duration as Illustrated by β2-Agonists
2001
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Regularity is a key element of maintenance drug treatment; compliance is crucial for treatment success. Once- or twice-daily intake of a drug is always easier to comply with than regimens requiring more frequent dosing. Bronchodilating treatment was used as an example to illustrate how sustained duration of effect can be achieved by two different approaches: oral administration of the terbutaline prodrug bambuterol and inhalation of formoterol. Bioanalytical methods were employed to monitor the kinetic fate of bambuterol and formoterol in plasma, urine, or faeces. Generated terbutaline in plasma was used as a marker of effect for bambuterol. Established clinical laboratory tests were used to assess local and systemic effects of inhaled formoterol compared with salbutamol. Recommended doses of bambuterol, 10-20 mg once daily in adults, normally produced plasma concentrations of the active moiety terbutaline within therapeutically relevant limits. Dose proportionality for terbutaline makes dosing with bambuterol predictable. Compared with adults, children should be given higher doses than indicated by their lower body weight. Pharmacokinetic analysis indicated that absorption of bambuterol was slow and multi-phasic and that slow biotransformation to terbutaline occurred both presystemically and systemically. Systemically circulating formoterol was rapidly eliminated, the inactive (S;S)-formoterol more rapidly than the active (R;R)-formoterol. An inactive phenol glucuronide was the main metabolite, and a previously unknown sulphate metabolite was discovered. Duration of systemically mediated cardiovascular or metabolic side-effects of inhaled formoterol seemed not to differ from those of an inhaled systemically equieffective dose of salbutamol. There was a trend suggesting that the magnitude of systemic side-effects may be less pronounced after inhalation of formoterol compared with a locally equieffective dose of inhaled salbutamol. Both approaches to sustaining stimulation of β2-adrenoceptors have their pros and cons. Bambuterol can be dosed orally once daily, but full effect is reached slowly. The effect of formoterol is reached within a few minutes, but administration must occur via the lungs, often twice daily. Both treatments, however, give 24-h symptom relief during regular treatment.
27.
28.
Steensland, Pia, 1972-
(författare)
Anabolic Androgenic Steroids and the Brain : Studies of Neurochemical and Behavioural Changes Using an Animal Model
2001
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
A new group of anabolic androgenic steroid (AAS) users has developed during the last two decades. This group consists primarily of young men interested in improving their physical appearance. Within this group, AAS are sometimes used together with other illicit drugs, alcohol and nicotine. Brutal and violent crimes have been committed under the influence of AAS, possibly because of AAS psychiatric side effects, ranging from increased aggression and psychosis to depression. Unfortunately, the biochemical mechanisms behind these effects are poorly understood.In this thesis we used an animal model to study biochemical and behavioural effects of chronic AAS treatment (15 mg/kg/day of nandrolone decanoate for 14 days). The effect on the endogenous opioid peptides and the expression of immediate-early gene protein Fos in various brain regions were studied using radioimmunoassay and immunohistochemistry, respectively. In addition, we studied AAS effect on voluntary alcohol consumption and defensive behaviours, including aggression. The results show that AAS enhance endogenous opioid activity and Fos expression in brain regions regulating reward, aggression and disinhibitory behaviours. An imbalance between two opioid systems with generally opposing effects, the enkephalins with euphoric and the dynorphins with dysphoric effects, was also found. This implies that AAS alter the ability to maintain a stable state of mind and the response to other drugs of abuse. The AAS pre-treated animals enhanced their alcohol intake, were more aggressive and showed lower fleeing and freezing reaction than the controls. In addition, AAS enhanced amphetamine-induced aggression when the amphetamine was given three weeks after the last AAS injection.The behavioural and biochemical results found in this thesis, support the hypothesis that use of AAS might lead to the development of dependence and may induce changes in the brain leading to disinhibitory behaviours.
29.
Stenberg, Patric
(författare)
Computational models for the prediction of intestinal membrane permeability
2001
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Lead compounds generated in high-throughput drug discovery programs often have unfavorable biopharmaceutical properties, resulting in a low success rate for such drug candidates in clinical development. Efficient and reliable methods that predict biopharmaceutical properties, such as intestinal permeability and solubility are therefore required in order to reduce the attrition rate during development of these compounds.One aim of this thesis was to identify molecular properties that are important for intestinal drug permeability using a wide range of drugs and model compounds. A second aim was to develop computational models for predicting intestinal drug permeability based on these properties.The calculated molecular descriptors ranged from the simple counting of atoms and fragments to more complex descriptors derived from molecular mechanics and quantum mechanics calculations. Particular attention was given to descriptors associated with molecular surface areas. Descriptors calculated by the various methods were used to establish structure-permeability relationships for conventional drugs, peptide derivatives and large, lipophilic compounds generated by high-throughput pharmacological screening. Caco-2 cell monolayer permeabilities were determined for a structurally diverse set of compounds and were used to predict human intestinal membrane permeability and to develop computational models.From these investigations, several new models for the computational prediction of intestinal membrane permeability were developed. Models were developed that are suitable for the prediction of membrane permeability to specific types of drugs, as well as models that are more generally applicable. One of these general models is based on partitioned total molecular surface areas, and this model can be used to predict intestinal membrane permeability to structurally diverse compounds. It was also demonstrated how these models can be applied in a manner that increases both the accuracy of the prediction and the throughput. In addition, a simplified protocol based on Caco-2 cells for the experimental prediction of intestinal permeability was developed. These improvements can be used to construct highly effective experimental and computational filters for use in drug discovery and development.
30.
Tan-No, Koichi, et al.
(författare)
Antinociceptive effect produced by intracerebroventricularly administered dynorphin A is potentiated by p-hydroxymercuribenzoate or phosphoramidon in the mouse formalin test
2001
Ingår i: Brain Research. - 0006-8993 .- 1872-6240. ; 891:1-2, s. 274-280
Tidskriftsartikel (refereegranskat) abstract
The antinociceptive effects of intracerebroventricularly (i.c.v.) administered dynorphin A, an endogenous agonist for kappa-opioid receptors, in combination with various protease inhibitors were examined using the mouse formalin test in order to clarify the nature of the proteases involved in the degradation of dynorphin A in the mouse brain. When administered i.c.v. 15 min before the injection of 2% formalin solution into the dorsal surface of a hindpaw, 1-4 nmol dynorphin A produced a dose-dependent reduction of the nociceptive behavioral response consisting of licking and biting of the injected paw during both the first (0-5 min) and second (10-30 min) phases. When co-administered with p-hydroxymercuribenzoate (PHMB), a cysteine protease inhibitor, dynorphin A at the subthreshold dose of 0.5 nmol significantly produced an antinociceptive effect during the second phase. This effect was significantly antagonized by nor-binaltorphimine, a selective kappa-opioid receptor antagonist, but not by naltrindole, a selective delta-opioid receptor antagonist. At the same dose of 0.5 nmol, dynorphin A in combination with phosphoramidon, an endopeptidase 24.11 inhibitor, produced a significant antinociceptive effect during both phases. The antinociceptive effect was significantly antagonized by naltrindole, but not by nor-binaltorphimine. Phenylmethanesulfonyl fluoride (PMSF), a serine protease inhibitor, bestatin, a general aminopeptidase inhibitor, and captopril, an angiotensin-converting enzyme inhibitor, were all inactive. The degradation of dynorphin A by mouse brain extracts in vitro was significantly inhibited only by the cysteine protease inhibitors PHMB and N-ethylmaleimide, but not by PMSF, phosphoramidon, bestatin or captopril. The present results indicate that cysteine proteases as well as endopeptidase 24.11 are involved in two steps in the degradation of dynorphin A in the mouse brain, and that phosphoramidon inhibits the degradation of intermediary delta-opioid receptor active fragments enkephalins which are formed from dynorphin A.
