The expression level of muscarinic M1 receptor subtypes in different regions of rat brain

Abstract

Objectives: Post-traumatic stress disorder (PTSD) is characterized

by life threatening trauma, overexcitation, flashbacks and

nightmares. Research on PTSD is faced with the challenge of

understanding how a traumatic experience leads to long lasting

detrimental effects on behavior and functions of the brain. Many

pharmacological agents are available in the pharmacotherapy

of the PTSD where there is no adequate evidence to support the

efficacy of any specific agent. It is hypothesized that M1 muscarinic

receptor subtypes might play important role in the recall of

negative experience. The aim of this research is to investigate both

the behavioral and the molecular efficacy of chronic fluoxetine

(FLU) (2.5mg/day; i.p) treatment in PTSD and also the probable

effect of pharmacotherapy on M1 muscarinic receptor subtype

expression in rats.

Materials and Methods: For experimental design random

selection was performed to all groups; Control, Stress and

Treatment groups. The effects of chronic FLU treatment were

evaluated in terms of expression levels of the M1 receptors in the

hippocampus and the frontal cortex of the rats’ brain.

Results: When the rats were subjected to the trauma reminder

on the last day of the experiment (Day 30), the anxiety indexes

of the stress group were found to be significantly higher than the

control (P< 0.001). Moreover, it has been observed that chronic

FLU treatment restored the anxiety scores in stress groups by

lowering the anxiety indexes (P< 0.001).

Conclusion: In this study, it has been indicated that stress

induces anxiety like behavior and reduces M1 expression in the

hippocampus and the frontal cortex of the rats’ brain. These effects

can be prevented by lowering the dose of chronic FLU therapy.

Keywords

• Muscarinic receptors,Stress,Cat litter,Fluoxetine,Hippocampus,Frontal cortex

Sıçan farklı beyin bölgelerinde M1 muskarinik reseptör alt tipi seviyeleri

Abstract

Amaç: Travma sonrası stres bozukluğu (TSSB) yaşamı tehdit eden

travma, aşırı uyarılma, flashbackler ve kabuslar ile karakterizedir.

TSSB araştırmaları, travmatik bir deneyimin beyinin davranış

ve işlevleri üzerinde uzun süreli bozulma etkilerine yol açtığını

anlamanın zorluğuyla karşı karşıyadır. Herhangi bir spesifik ajanın

etkinliğini destekleyecek uygun kanıt olmadığında, TSSB’nin

farmakoterapisinde birçok farmakolojik ajan kullanılmaktadır.

Olumsuz bir deneyimin geri çağrılmasında M1 muskarinik reseptör

alt tiplerinin önemli rol oynayabileceği öngörülmektedir. Bu

araştırmanın amacı, TSSB’de kronik fluoksetin (FLU) (2.5 mg/

gün; i.p) tedavisinin hem davranışsal hem de moleküler etkinliğini

ve farmakoterapinin sıçanlarda M1 muskarinik reseptör alt tipi

ekspresyonu üzerine muhtemel etkisini araştırmaktır.

Gereç ve Yöntem: Deney tasarımında tüm gruplar rastgele

olarak seçilerek Kontrol, Stres ve Tedavi grupları oluşturulmuştur.

Kronik FLU tedavisinin etkileri, sıçan hipokampüs ve frontal

korteksinde, M1 reseptörlerinin ekspresyon seviyeleri açısından

değerlendirilmiştir.

Bulgular: Sıçanlar deneyin son gününde (30.Gün) travma

hatırlatıcılara maruz kaldıklarında, stres gruplarındaki anksiyete

indekslerinin kontrol grubuna göre belirgin bir şekilde arttığı

gözlemlenmiştir (P<0.001). Ayrıca, kronik FLU tedavisinin stress

gruplarında anksiyete değerlerini düşürerek geriye döndürdüğü

gözlemlenmiştir (P<0.001).

Sonuç: Bu çalışmada, stresin kaygı benzeri davranışları

arttırarak sıçan beyin hipokampüs ve frontal korteksinde M1

ekspresyon seviyesini azalttığı gözlemlenmiştir. Düşük doz

kronik FLU tedavisi ile bu etkilerin geri döndürülebileceği

öngörülmektedir.

Keywords

• Muskarinik reseptör,Stres,Kedi kumu,Fluoksetin,Hippokampüs,Frontal korteks

References

1. Schmidt U, Kaltwasser SF, Wotjak CT. Biomarkers in posttraumatic stress disorder: overview and ımplications for future research. Dis Markers 2013;1:43-54. doi:10.1155/2013/835876
2. Yehuda R. Risk and resilience in posttraumatic stress disorder. J Clin Psychiatry 2004;65:26-36.
3. Vanelzakker MB, Dahlgren MK, Davis FC, et al. From Pavlov to PTSD: the extinction of conditioned fear in rodents, humans, and anxiety disorders. Neurobiol Learn Mem 2014;113:3-18. doi: 10.1016/j.nlm.2013.11.014.
4. Aslan N, Goren Z, Onat F, Oktay S. Carbachol-induced pressor responses and muscarinic M1 receptors in the central nucleus of amygdala in conscious rats. Eu J Pharmacol 1997;333:63-7.
5. Ravindran LN, Stein MB. Pharmacotherapy of PTSD: premises, principles, and priorities. Brain Res Rev 2009;1293:24-39. doi: 10.1016/j.brainres.2009.03.037.
6. Armario A, Escorihuela RM, Nadal R. Long-term neuroendocrine and behavioral effects of a single exposure to stress in adult animals. Neurosci Biobehav Rev 2008;32:1121-35. doi: 10.1016/j.neubiorev.2008.04.003
7. Cohen H, Zohar J, Matar MA. The relevance of differential response to traumain an animal model of posttraumatic stress disorder. Biol Psychiatry 2003;59:1208-18. doi:10.1016/j. ejphar.2004.09.009
8. Adamec R, Bartoszyk GD, Burton P. Effects of systemic injections of vilazodone, a selective serotonin reuptake inhibitor and serotonin 1A receptor agonist, on anxiety induced by predator stress in rats. Eu J Pharmacol 2004;504:65-77.

9. Kafkafi N, Lipkind D, Benjamini Y, Golani I. SEE locomotor behavior test discriminates C57BL/6J and DBA/2J mouse inbred strains across laboratories and protocol conditions. Behav Neurosci 2003;117:464-77. doi: 10.1517/14728210902972494
10. Baker DG, Nievergelt CM, Risbrough VB. Posttraumatic stress disorder: emerging concepts of pharmacotherapy. Expert Opin Emerg Drugs 2009;14:251-72. doi: 10.1517/14728210902972494.
11. Mendes DD, Mello MF, Ventura P, Passarela CM, Mari JJ. A systematic review on the effectiveness of cognitive behavioral therapy for posttraumatic stress disorder. Int J Psychiatry Med 2008;38:241-59. doi: 10.2190/PM.38.3.b
12. Cohen H, Matar MA, Richter-Levin G, Zohar J. The contribution of an animal model toward uncovering biological risk factors for PTSD. Ann N Y Acad Sci 2006;1071:335-50. doi: 10.1196/annals.1364.026
13. Matar MA, Cohen H, Kaplan Z, Zohar J. The effect of early poststressor intervention with sertraline on behavioral responses in an animal model of post-traumatic stress disorder. Neuropsychopharmacology 2006;31:2610-8. doi : 10.1038/sj.npp.1301132
14. Mazor A, Matar MA, Kaplan Z, Koziovsky N, Zohar J, Cohen H. Gender related qualitative differences in baseline and post-stress anxiety responses are not reflected in the incidence of criterion-based PTSD-like behaviour patterns. World J Biol Psychiatry. 2009;10:856–69. PMID:2864480
15. Blancharda DC, Griebelc G, Blanchardd RJ. Conditioning and residual emotionality effects of predator stimuli: some reflections on stress and emotion. Prog Neuropsychopharmacol Biol Psychiatry. 2003; 27:1177–85. doi:10.1016/j.pnpbp.2003.09.012
16. Pelow S, Chopin P, File SE, Briley M. Validation of openclosed arm entries in an elevated plus maze as measure of anxiety in the rat. J Neurosci Methods. 1985;14:149–67. PMID:2864480
17. Paxinos G, Watson C. The rat brain in stereotaxic coordinates. 2nd ed. London: Academic Press; 1986.
18. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951;193:265–327. PMID:14907713
19. Zoladz PR, Diamond DM. Predator-based psychosocial stress animal model of PTSD: Preclinical assessment of traumatic stress at cognitive, hormonal, pharmacological, cardiovascular and epigenetic levels of analysis. Exp Neurol. 2016; 284:211–9. doi: 10.1016/j.expneurol.2016.06.003
20. Wall PM, Flinn J, Messier C. Infralimbic muscarinic M1 receptors modulate anxiety-like behavior and spontaneous working memory in mice. Psychopharmacology 2004;155:58–68. PMID: 11374337
21. Degroot A, Nomikos GG. Fluoxetine disrupts the integration between anxiety and aversive memories. Neuropsychopharmacology 2005;30:391–400. doi:10.1038/ sj.npp.1300624
22. Cohen H, Liu T , Kozlovsky N, Kaplan Z , Zohar J, Mathe AA. The Neuropeptide Y (NPY)-ergic System is Associated with Behavioral Resilience to Stress Exposure in an Animal Model of Post-Traumatic Stress Disorder. Neuropsychopharmacology. 2012;37:350–63. doi: 10.1038/ npp.2011.230
23. Everitt BJ, Robbins TW. Central cholinergic systems and cognition. Annu Rev Psychol. 1997;48:649–84. doi:10.1146/ annurev.psych.48.1.649
24. File SE, Gonzales LE, Andrews N. Endogenous acetylcholine in the dorsal hippocampus reduces anxiety through actions on nicotinic and muscarinic1 receptors. Behav Neurosci. 1998;112:352-9. PMID:9588482
25. Sienkiewicz-Jarosz H, Czlonkowska AI, Siemiatkowski M, Maciejak P, Szyndler J, Plaznik Z. The effects of physostigmine and cholinergic receptor ligands on noveltyinduced neophobia. J Neural Transm. 2000;107:1403–12. doi: 10.1007/s007020070004
26. Aykac A, Aydın B, Cabadak H, Goren ZM. The change in muscarinic receptor subtypes in different brain regions of rats treated with fluoxetine or propranolol in a model of posttraumatic stress disorder. Behavi Brain Res 2012; 232:124-9. doi: 10.1016/j.bbr.2012.04.002
27. Javelot H, Weiner L, Terramorsi R, Rougeot C, Lalonde R, Messaoudi M. Efficacy of chronic antidepressant treatments in a new model of extreme anxiety in rats. Depress Res Treat 2011; 2011:1-10. doi: 10.1155/2011/531435