1.
Nylander, Erik, 1986-
(författare)
The effects of growth hormone on opioid-induced toxicity in vitro
2019
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
There is an ongoing opioid crisis in the United States that is portrayed by a large number of opioid-related deaths. Many of these cases involve commonly used prescription opioids, such as morphine, oxycodone, fentanyl, and methadone. This is concerning and highlights the problems associated with long-term opioid treatment. In addition to opioid-related deaths, long-term opioid use may impact higher brain functions, such as cognitive function. The cause of cognitive decline following opioid treatment may be associated with increased neuronal cell death, inhibited neurogenesis, and altered volumes of specific brain regions important for cognition. Growth hormone (GH), a pituitary hormone regulated by the hypothalamic somatotropic axis, may counteract several of these effects. The hormone, alongside with its mediator insulin-like growth factor-1 (IGF-1), is associated with pro-cognitive effects and display promising neuroprotective actions in the CNS. The main aim for this thesis was to examine the impact of opioids on cell viability and the potentially protective, restorative, and effects linked to pro-cognitive properties of GH in mixed neuronal cell cultures and cell lines. The results clearly display that specific opioids, such as methadone, decrease cell viability, possibly via negative effects on mitochondrial morphology. GH treatment alleviated the negative effects of methadone in cortical cell cultures as well as successfully restored mitochondrial and membrane integrity past injury. Moreover, GH treatment to primary hippocampal cell cultures increased the number of dendritic spines, which are linked to higher cognitive functions, indicating that the hormone act as a cognitive enhancer in the CNS. In conclusion, this thesis provides further evidence that opioids negatively impact cell viability, an effect that may underlie reduced cognitive function as seen in several patients consuming opioids-long term. GH was able to counteract these effects and also able to restore damaged cellular functions. This thesis further confirms the essential role of GH in acting as a cognitive enhancer in the CNS, highlighting the potential role of GH as a treatment for cognitive dysfunctions.
2.
Zelleroth, Sofia, 1990-, et al.
(författare)
Structurally different anabolic androgenic steroids reduce neurite outgrowth and neuronal viability in primary rat cortical cell cultures
2021
Ingår i: Journal of Steroid Biochemistry and Molecular Biology. - : Elsevier BV. - 0960-0760 .- 1879-1220. ; 210
Tidskriftsartikel (refereegranskat) abstract
The illicit use of anabolic androgenic steroids (AAS) among adolescents and young adults is a major concern due to the unknown and unpredictable impact of AAS on the developing brain and the consequences of this on mental health, cognitive function and behaviour. The present study aimed to investigate the effects of supra-physiological doses of four structurally different AAS (testosterone, nandrolone, stanozolol and trenbolone) on neurite development and cell viability using an in vitro model of immature primary rat cortical cell cultures. A high-throughput screening image-based approach, measuring the neurite length and number of neurons, was used for the analysis of neurite outgrowth. In addition, cell viability and expression of the Tubb3 gene (encoding the protein beta-III tubulin) were investigated. Testosterone, nandrolone, and trenbolone elicited adverse effects on neurite outgrowth as deduced from an observed reduced neurite length per neuron. Trenbolone was the only AAS that reduced the cell viability as indicated by a decreased number of neurons and declined mitochondrial function. Moreover, trenbolone downregulated the Tubb3 mRNA expression. The adverse impact on neurite development was neither inhibited nor supressed by the selective androgen receptor (AR) antagonist, flutamide, suggesting that the observed effects result from another mechanism or mechanisms of action that are operating apart from AR activation. The results demonstrate a possible AAS-induced detrimental effect on neuronal development and regenerative functions. An impact on these events, that are essential mechanisms for maintaining normal brain function, could possibly contribute to behavioural alterations seen in AAS users.
3.
Guimond, Marie-Odile, et al.
(författare)
Saralasin and Sarile Are AT2 Receptor Agonists
2014
Ingår i: ACS Medicinal Chemistry Letters. - : American Chemical Society (ACS). - 1948-5875 .- 1948-5875. ; 5:10, s. 1129-1132
Tidskriftsartikel (refereegranskat) abstract
Saralasin and sarile, extensively studied over the past 40 years as angiotensin II (Ang II) receptor blockers, induce neurite outgrowth in a NG108-15 cell assay to a similar extent as the endogenous Ang II. In their undifferentiated state, these cells express mainly the AT2 receptor. The neurite outgrowth was inhibited by preincubation with the AT2 receptor selective antagonist PD 123,319, which suggests that the observed outgrowth was mediated by the AT2 receptor. Neither saralasin nor sarile reduced the neurite outgrowth induced by Ang II proving that the two octapeptides do not act as antagonists at the AT2 receptor and may be considered as AT2 receptor agonists.
4.
5.
Andersson, Hanna, Dr. 1979-, et al.
(författare)
Ligands to the (IRAP)/AT4 receptor encompassing a 4-hydroxydiphenylmethane scaffold replacing Tyr2
2008
Ingår i: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 16:14, s. 6924-6935
Tidskriftsartikel (refereegranskat) abstract
Analogues of the hexapeptide angiotensin IV (Ang IV, Val(1)-Tyr(2)-Ile(3)-His(4)-Pro(5)-Phe(6)) encompassing a 4-hydroxydiphenylmethane scaffold replacing Tyr(2) and a phenylacetic or benzoic acid moiety replacing His(4)-Pro(5)-Phe(6) have been synthesized and evaluated in biological assays. The analogues inhibited the proteolytic activity of cystinyl aminopeptidase (CAP), frequently referred to as the insulin-regulated aminopeptidase (IRAP), and were found less efficient as inhibitors of aminopeptidase N (AP-N). The best Ang IV mimetics in the series were approximately 20 times less potent than Ang IV as IRAP inhibitors. Furthermore, it was found that the ligands at best exhibited a 140 times lower binding affinity to the membrane-bound IRAP/AT4 receptor than Ang IV. Although the best compounds still exert lower activities than Ang IV, it is notable that these compounds comprise only two amino acid residues and are considerably less peptidic in character than the majority of the Ang IV analogues previously reported as IRAP inhibitors in the literature.
6.
Axén, Andreas, et al.
(författare)
Cyclic insulin-regulated aminopeptidase (IRAP)/AT(4) receptor ligands
2006
Ingår i: Journal of Peptide Science. - : Wiley. - 1075-2617 .- 1099-1387. ; 12:11, s. 705-713
Tidskriftsartikel (refereegranskat) abstract
The angiotensin IV receptor (AT(4) receptor) is the insulin-regulated aminopeptidase enzyme (IRAP, EC 3.4.11.3). This membrane-spanning enzyme belongs to the M1 family of zinc-dependent metallo-peptidases. It has been proposed that AT4 receptor ligands exert their physiological effects by binding to the active site of IRAP and thereby inhibiting the catalytic activity of the enzyme. The biological activity of a large series of linear angiotensin IV analogs was previously disclosed. Herein, the synthesis and biological evaluation of a series of angiotensin IV analogs, encompassing macrocyclic ring systems of different sizes, are presented. It is demonstrated that disulfide cyclizations of angiotensin IV can deliver ligands with high IRAP/AT4 receptor affinity. One ligand, with an 11-membered ring system (4), inhibited human IRAP and aminopeptidase N (AP-N) activity with similar potency as angiotensin IV but was considerably more stable than angiotensin IV toward enzymatic degradation. The compound provides a promising starting point for further optimization toward more drug-like derivatives. The cyclic constrained analogs allowed us to propose a tentative bioactive conformation of angiotensin IV and it seems that the peptide adopts an inverse gamma-turn at the C-terminal.
7.
Axén, Andreas, et al.
(författare)
Small potent ligands to the insulin-regulated aminopeptidase (IRAP)/AT(4) receptor
2007
Ingår i: Journal of Peptide Science. - : Wiley. - 1075-2617 .- 1099-1387. ; 13:7, s. 434-444
Tidskriftsartikel (refereegranskat) abstract
Angiotensin IV analogs encompassing aromatic scaffolds replacing parts of the backbone of angiotensin IV have been synthesized and evaluated in biological assays. Several of the ligands displayed high affinities to the insulin-regulated aminopeptidase (IRAP)/AT4 receptor. Displacement of the C-terminal of angiotensin IV with an o-substituted aryl acetic acid derivative delivered the ligand 4, which exhibited the highest binding affinity (Ki = 1.9 nM). The high affinity of this ligand provides support to the hypothesis that angiotensin IV adopts a -turn in the C-terminal of its bioactive conformation.Ligand (4) inhibits both human IRAP and aminopeptidase N-activity and induces proliferation of adult neural stem cells at low concentrations. Furthermore, ligand 4 is degraded considerably more slowly in membrane preparations than angiotensin IV. Hence, it might constitute a suitable research tool for biological studies of the (IRAP)/AT4 receptor.
8.
Borhade, Sanjay R, et al.
(författare)
Inhibition of Insulin-Regulated Aminopeptidase (IRAP) by Arylsulfonamides
2014
Ingår i: ChemistryOpen. - : Wiley. - 2191-1363. ; 3:6, s. 256-263
Tidskriftsartikel (refereegranskat) abstract
The inhibition of insulin-regulated aminopeptidase (IRAP, EC 3.4.11.3) by angiotenesin IV is known to improve memory and learning in rats. Screening 10 500 low-molecular-weight compounds in an enzyme inhibition assay with IRAP from Chinese Hamster Ovary (CHO) cells provided an arylsulfonamide (N-(3-(1H-tetrazol-5-yl)phenyl)-4-bromo-5-chlorothiophene-2-sulfonamide), comprising a tetrazole in the meta position of the aromatic ring, as a hit. Analogues of this hit were synthesized, and their inhibitory capacities were determined. A small structure-activity relationship study revealed that the sulfonamide function and the tetrazole ring are crucial for IRAP inhibition. The inhibitors exhibited a moderate inhibitory potency with an IC50=1.1±0.5 μm for the best inhibitor in the series. Further optimization of this new class of IRAP inhibitors is required to make them attractive as research tools and as potential cognitive enhancers.
9.
Brolin, Erika, et al.
(författare)
Chronic administration of morphine using mini-osmotic pumps affects spatial memory in the male rat
2018
Ingår i: Pharmacology, Biochemistry and Behavior. - : Elsevier BV. - 0091-3057 .- 1873-5177. ; 167, s. 1-8
Tidskriftsartikel (refereegranskat) abstract
The use of opioid analgesics to treat non-cancer pain has increased over the years. Many chronic pain patients suffer from numerous adverse effects, such as reduced quality of life, development of dependence, and cognitive impairments. Cognitive processes are regulated by several systems, one of which involves growth hormone (GH) and its secondary mediator insulin-like growth factor-1 (IGF-1), but also glutamatergic transmission, including receptors such as the N-methyl-D-aspartate (NMDA)-receptor complex. In the laboratory, repeated injections are commonly used to establish animal models of long-term or chronic drug exposure. However, in the present study, we aimed to mimic a more human dose regimen using constant drug delivery provided by mini-osmotic pumps implanted subcutaneously in male Sprague Dawley rats. After developing opioid tolerance the cognitive function of rats was studied. Spatial learning and memory capabilities were evaluated using the rat Morris water maze (MWM). Moreover, gene expression related to the GH/IGF-1-axis and the NMDA-receptor system was analyzed using quantitative PCR (qPCR) and plasma levels of IGF-1 were assessed using the ELISA technique. Our results demonstrate that rats exposed to morphine for 27 days display memory impairments in the MWM probe trial. However, the behavioral effects of chronic morphine treatment were not accompanied by any significant differences in terms of mRNA expression or IGF-1 plasma concentration. The animal model used in this study provides a simple and suitable way to investigate the behavioral and neurochemical effects of chronic opioid treatment similar to the exposure seen in human pain patients.
10.
Brolin, Erika, 1984-
(författare)
Growth hormone in the brain : Focus on cognitive function
2017
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Cognitive impairments are an increasing health problem worldwide. In the developed countries, the average life expectancy has dramatically increased over the last decades, and with an elderly population more cases of cognitive impairments appear. Age, genetics, and different medical conditions such as diabetes mellitus, and substance use disorders may all contribute to declined cognitive ability. Physiological functions also decrease with increasing age, as does the activity of the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis. Interestingly, both GH and IGF-1 are recognized for their neuroprotective effects and cognitive enhancement. The overall aim of this thesis was to investigate the impact of the somatotrophic axis (i.e. GH/IGF-1 axis) in rodents with cognitive deficiencies induced by diabetes or long-term drug exposure. For the first time cognitive impairments were characterized in diabetic mice using a spatial learning and memory task called the Barnes maze (BM). In diabetic mice, impaired learning in the BM was associated with decreased expression of the GH receptor (GHR) in the frontal cortex, a region important for e.g. working memory. Treatment with GH reversed certain cognitive impairments seen in diabetic animals. In rats treated with gamma-hydroxybutyrate (GHB), a significant decrease of Igf1 mRNA expression in the frontal cortex was observed. This observation may explain the impaired cognitive function previously seen following GHB administration. Furthermore, rats exposed to chronic morphine delivered in mini-osmotic pumps displayed memory impairments in the Morris water maze (MWM), an effect that seems to be associated with the composition of the N-methyl-d-aspartate (NMDA) receptor complex in the frontal cortex. In conclusion, the result strengthens the evidence for GH being a cognitive enhancer. Moreover, the result within this thesis identifies the frontal cortex as an important brain region, where gene expression related to the somatotrophic system is affected in rodents with cognitive impairments. The thesis especially emphasizes the importance of the local somatotrophic system in the brain with regard to cognitive function.
