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Long-term treatment with antidepressants, but not environmental stimulation, induces expression of NP2 mRNA in hippocampus and medial habenula
Linköpings universitet, Institutionen för klinisk och experimentell medicin, Geriatrik. Linköpings universitet, Hälsouniversitetet. (Geriatrik)
Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Hälsouniversitetet. (Geriatrik)
Linköpings universitet, Institutionen för klinisk och experimentell medicin, Cellbiologi. Linköpings universitet, Hälsouniversitetet. (Cellbiologi)
Linköpings universitet, Institutionen för klinisk och experimentell medicin, Geriatrik. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Närsjukvården i centrala Östergötland, Geriatriska kliniken. (Geriatrik)
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2010 (Engelska)Ingår i: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1328, s. 24-33Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Neuronal Pentraxin 2 (NP2, Narp), known to mediate clustering of glutamatergic AMPA receptors at synapses, is involved in activity-dependent synaptogenesis and synaptic plasticity. In experimental settings, antidepressant treatment as well as a stimulating environment has a positive influence on cognition and hippocampal plasticity. This study demonstrates that NP2 mRNA is robustly expressed in the hippocampus and the medial habenula (MHb), both regions implicated in cognitive functions. Furthermore, NP2 mRNA expression is enhanced in the hippocampal subregions as well as in the MHb after long-term treatment with antidepressant drugs of various monoaminergic profiles, indicating a common mode of action of different antidepressant drugs. This effect occurs at the time frame where clinical response is normally achieved. In contrast, neither environmental enrichment nor deprivation has any influence on long-term NP2 mRNA expression. These findings support an involvement of NP2 in the pathway of antidepressant induced plasticity, but not EE induced plasticity; that NP2 might constitute a common link for the action of different types of antidepressant drugs and that the MHb could be a putative region for further studies of NP2.

Ort, förlag, år, upplaga, sidor
Elsevier , 2010. Vol. 1328, s. 24-33
Nyckelord [en]
Neuronal pentraxins, narp, habenula, hippocampus, synaptic plasticity, antidepressant
Nationell ämneskategori
Medicin och hälsovetenskap
Identifikatorer
URN: urn:nbn:se:liu:diva-51408DOI: 10.1016/j.brainres.2010.03.004ISI: 000277682400003OAI: oai:DiVA.org:liu-51408DiVA, id: diva2:274671
Anmärkning
On the day of the defence day the status of this article was: Submitted.Tillgänglig från: 2009-10-30 Skapad: 2009-10-30 Senast uppdaterad: 2019-10-14Bibliografiskt granskad
Ingår i avhandling
1. Pharmacological and Developmental Aspects on Neuronal Plasticity
Öppna denna publikation i ny flik eller fönster >>Pharmacological and Developmental Aspects on Neuronal Plasticity
2009 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Neuronal plasticity means the ability of the brain, its cells and networks to adapt and adjust to new challenges, a process which is ongoing throughout life. The goal of this thesis was to gain better understanding of the molecular events that follow different types of stimulations of brain structures such as the hippocampus, a key region for cognitive functions with overriding control on the corticosteroid system. A better knowledge of the mechanisms involved in neuronal plasticity is fundamental in the development of strategies for improving health in patients suffering from major depression or cognitive disorders such as Alzheimer’s disease.

Antidepressant drugs induce the expression of several genes involved in neuronal plasticity, a mechanism which may explain the several weeks time lag between treatment initiation and clinical effect commonly observed in patients. Besides, there are indications that disturbances in the corticosteroid system are involved in the pathogenesis of major depression. Therefore, the mRNA expression of the glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) as well as of the immediate-early genes NGFI-A and NGFI-B was analyzed using in situ hybridization in the hippocampus and cortex after 21 days treatment with various antidepressant drugs having different monoaminergic profiles. The mRNA expression of the transcription factors was selectively increased depending on region and also on the monoaminergic profile of the drug given. Generally, drugs with less specificity for monoamines had an overall more anatomically wide-spread inducible effect.

In a follow-up study the message expression of the synaptic protein NP2 was investigated in a similar setting where long-term (21 days) was compared with short-term (3 days) antidepressant treatment. In addition to the hippocampus, the medial habenula, a relay station within the limbic system was analyzed. Overall there was an upregulation of NP2 mRNA expression following long-term treatment irrespective of the monoaminergic profile of the drug. Simultaneously, NP2 mRNA was analyzed in rats exposed to enriched, normal or deprived environments respectively, an experimental setting known to affect neuronal plasticity. However, in contrast to the pharmacological treatment, this environmental stimulation did not lead to alterations in NP2 mRNA expression in any of the regions studied.

Finally, the function of NP2 as well as the closely related proteins NP1 and NPR was investigated. The “knock-out mouse” technique was used to eliminate these neuronal pentraxins (NPs), both individually and in various combinations. Since previous data had suggested that the NPs are involved in synaptic development, axonal refinement in the visual system during development was analyzed in these animals. In the NP1/NP2 knock-out mice, synaptic formation, axonal development and refinement occurred at a significantly slower rate than in wild-type mice, indicating that the NPs may be necessary for activity-dependent synaptogenesis.

In conclusion, the results of the studies constituting this thesis demonstrate that long-term treatment with antidepressant drugs, possessing different monoaminergic profiles, has selective effects on the expression of NGFI-A, NGFI-B, GR and MR in the mammalian brain. In general, the least selective drugs exhibit the most profound effect suggesting that induction of neuronal plasticity is more effective with multiple neuronal inputs. The results also show that NP2 expression is induced by antidepressant drugs, in contrast to environmental stimulation, supporting the presence of different pathways for inducing neuronal plasticity depending on type of stimuli. Finally, this thesis indicates that the neuronal pentraxins play an important part in synaptic development.

 

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2009. s. 62
Serie
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1151
Nationell ämneskategori
Medicin och hälsovetenskap
Identifikatorer
urn:nbn:se:liu:diva-51450 (URN)978-91-7393-519-7 (ISBN)
Disputation
2009-12-18, Berzeliussalen, Hälsouniversitetet, Campus US, Linköpings Universitet, Linköping, 00:00 (Svenska)
Opponent
Handledare
Tillgänglig från: 2009-11-02 Skapad: 2009-11-02 Senast uppdaterad: 2009-11-02Bibliografiskt granskad

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