Recently anti-inflammatory effects of antidepressant drugs have been demonstrated. Venlafaxine belongs to newer antidepressants with serotonin norepinephrine re-uptake suppression belongings.
The hurting relieving belongingss of venlafaxine in different hurting theoretical accounts such as neurogenic hurting, diabetic neuropathy and fibromyalgia have been demonstrated.
Anti-inflammatory effects of venlafaxine and besides its implicit in mechanisms remain ill-defined. The present survey was designed to measure the anti-inflammatory effects of venlafaxine and determine possible mechanisms underlying this consequence. Therefore we have examined the anti-inflammatory effects of intraperitoneal ( i.p. ) and intracerebroventricular ( i.c.v. ) disposal of venlafaxine in the carrageenan-induced paw hydrops in rats.
Our consequences showed that both i.p. ( 50 and 100 mg/kg ) and i.c.v. ( 50 and 100 ?g/rat ) injection of venlafaxine inhibited carrageenan-induced paw hydrops. We besides found that both i.p. and i.c.v. disposal of venlafaxine significantly decreased myeloperoxidase ( MPO ) activity, interleukin ( IL ) -1? and tumour mortification factor ( TNF ) -? coevals.
Finally, we tried to change by reversal the anti-inflammatory consequence of venlafaxine by yohimbine ( 5 mg/kg i.p. ) an alpha2-adrenergic adversary. Our consequences showed that applied adversaries failed to alter the anti-inflammatory consequence of venlafaxine.
These consequences demonstrated the anti-inflammatory effects of systemic and cardinal venlafaxine injections and showed that these effects mediated largely through the suppression IL-1? and TNF-? coevals and reduced MPO activity in the site of redness.
Cardinal words:Venlafaxine, Carrageenan, Inflammation, Rat
Recently the function of antidepressants, peculiarly conventional tricyclic antidepressants ( TCAs ) such as Elavil, Pamelor, and Adapin for relieving assorted types of hurting, such as inflammatory and neuropathic hurting have been shown.
Furthermore it has been reported that Prozac, paroxetine and Zoloft can modulate the ability of microglia to bring forth the proinflammatory-cytokine such as tumour mortification factor-a ( TNF-a ) and the free extremist azotic oxide ( NO ) . ( Hashioka et al. , 2007, 2009 ; Horikawa
et al. , 2010 ; Hwang et al. , 2008 ) .
Venlafaxine is a structurally fresh phentylethylamine which belongs to newer antidepressant drug that blocks the synoptosomal consumption of norepinephrine and 5-hydroxytryptamine ( Lloyd 1992 ) .
The hurting relieving belongingss of venlafaxine in different hurting theoretical accounts such as neurogenic hurting, diabetic neuropathy and fibromyalgia have been demonstrated ( 3-5 ) .
In add-on venlafaxine does non bring on the usual tricyclic antidepressants ( TCAs ) side-effects caused by their anticholinergic, anti-histaminic and alpha-1 sympathomimetic counter belongingss ( Ellingrod et al, 1994 ) .
Therefore this drug could be a fresh and promising intervention in inflammatory strivings. But the anti-inflammatory consequence of venlafaxine and besides underlying mechanisms which may be involved in this consequence has non been to the full examined. The purposes of the present survey were to ( a ) determine the consequence of systemic venlafaxine injections on the carrageenan-induced paw hydrops, ( B ) examine the possible engagement of cardinal mechanism in the anti-inflammatory activity of venlafaxine, ( degree Celsius ) determine the consequence of venlafaxine on the myeloperoxidase activity in the site of redness, ( vitamin D ) measure the consequence of venlafaxine on inflammatory cytokines such as IL-1? and TNF-? coevals and ( vitamin E ) look into the possible function of alpha2-adrenergic receptors in this consequence of venlafaxine.
2. Materials and Methods
2.1. Animals and lodging conditions
The experiments were performed on male Sprague–Dawley rats ( 200–250 g ) . They were housed four per coop, in a room under controlled temperature ( 23±2 °C ) , humidness ( 50 % ) and illuming ( 12/12 H light/dark rhythm ) , with nutrient and H2O available ad libitum.
Venlafaxine was obtained from Darupakhsh pharmaceutical Co. , Iran. Carrageenan ( lambda ) was obtained from Fluka Chemical ( Switzerland ) and dissolved in saline solution. Aprotinin A, Hexadecyl trimethylammonium bromide ( HTAB ) , phenylmethylsulfonyl fluoride, bovine serum albumen, ethylenediaminetetraacetic acid ( EDTA ) , benzethonium chloride, and Tween 20 were all purchased from Sigma Chemical Company ( St. Louis, MO, USA ) . IL-1? ( ALPCO, USA ) , and TNF-? ( R & A ; D Company, USA ) kits were used for measuring the cytokines degrees.
2.3. Surgical process
The rats were anesthetized with i.p. injection of Ketalar ( 50 mg/kg ) and xylazine ( 10 mg/kg ) . Then an i.c.v. cannula was implanted with stereotaxic co-ordinates: AP, ?0.8 millimeter ; L, 1.4 millimeter ; and V, 3.3 millimeter, based on Paxinos and Watson Atlass ( Budantsev et al. , 1993 ) . The rats were handled daily for extra five yearss before the experiments to familiarise them to use and lessen nonspecific emphasis responses. Rats with the i.c.v. cannulas were sacrificed at the terminal of the experiments, and their encephalons were removed and examined to corroborate the right inserting of the cannula.
2.4. Carrageenan-induced paw hydrops
100 ?l of a 1 % ( w/v ) suspension of carrageenin lambda was injected subplantar in the right hind paw ( Winter et al.,1962 ) . Immediately before carrageenan injection and so at 4 H after that the volume of the paw was determined by a Plethysmometer ( Ugo Basile, Italy ) . The informations were expressed as the difference in the paw volume ( milliliter ) and were compared to pre-injection values.
2.5. Experimental design
All doses that applied in this experiment were chosen harmonizing to old surveies ( Hajhashemi et al. , 2010b ) .
In the first series of experiments, the consequence of venlafaxine ( 50 and 100 mg/kg, i.p. n=6 ) on paw hydrops was examine. Venlafaxine was injected 30 min before subplantar injection of carrageenin. Paw volumes ( milliliter ) were measured before carrageenin injection, and so once more, at 4 H after that to find the difference in paw volume. Control group received merely vehicle ( 5ml/kg i.p. ; n=6 ) . At the terminal of the experiments, animate beings were sacrificed, and the inflamed paw tissues were collected for cytokines and myeloperoxidase activity measuring.
In the 2nd series, we used the i.c.v. path to find the engagement of supraspinal degrees in the anti-inflammatory consequence of venlafaxine ( Hajhashemi et al. , 2010b ) .
Venlafaxine was injected swimmingly for 1 min through the i.c.v. cannula ( 50 and 100 ?g/rat, n=6 ) 30 min before carrageenan injections and the paw volumes were measured. The control group received vehicle ( i.c.v. ; 5 ?l ; n=6 ) . At the terminal of the experiments for cytokine and myeloperoxidase activity measuring animate beings were sacrificed, and the paw tissues were collected.
Finally, in order to measure the possible engagement the alpha2- sympathomimetic receptors in the repressive consequence of venlafaxine on carrageenan-induced redness, animate beings were pretreated with yohimbine ( 5 mg kg-1, i.p. , ) in co-administrated with venlafaxine.
2.6. Myeloperoxidase Activity Assay.
MPO activity, an index of polymorphonuclear leukocyte accretion, was measured in the inflamed paw. [ 24 ] . Paw tissue was chopped and homogenized in K phosphate buffer incorporating 0.5 % HTAB ( hexadecyltrimethylammonium bromide ) . Then, the homogenate was sonicated in an ice bath. After that, the suspensions were centrifuged at 15,000 revolutions per minute for 15 min at 4a-¦C and so 2.9mL of 50mM K phosphate buffer ( pH 6.0 ) incorporating O-dianisidine dihydrochloride ( 0.167 mg/mL ) and 0.005 % H peroxide was added to the supernatant. The optical density of the reaction mixture was measured at 450nm utilizing a UV-Vis spectrophotometer. MPO activity was expressed in units ( U ) per gm of wet tissue weight.
2.7. Measurement of the IL-1? and TNF-? degree in the rat paw
TNF-? and IL-1? degrees in the whole tegument of inflamed paws were measured ( Nacife et al. , 2004 ) . The tissue samples were weighed ; snap frozen on liquid N and stored at ?70 °C. Tissue was homogenized in phosphate buffered saline ( PBS ; pH=7.4 ) incorporating Tween-20, 0.5 % , 0.4 M NaCl, 0.05 % , 0.1 millimeter phenylmethylsulfonyl fluoride, bovine serum albumen, aprotinin A 20 KI, 0.1 millimeter benzethonium chloride, and 10 millimeter EDTA. The homogenates were centrifuged at 12,000?g for 30 min at 4 °C, and so ELISA kits were used to mensurate the degrees of IL-1? and TNF-? in the supernatants.
2.8. Statistical analysis
The informations are expressed as the means±S.E.M. Data were compared by one-way analysis of discrepancy ( ANOVA ) followed by Fisher LSD post-hoc trial for multiple comparings. The chance of P & lt ; 0.05 was considered to demo important differences for all comparings made.
3.1. Consequence of i.p. injection of venlafaxine on carrageenan-induced paw hydrops
As shown in Fig. 1, i.p. injection of venlafaxine at doses of 50 and 100 mg/kg significantly decreased the development of paw hydrops as compared to the control group.
3.2. Consequence of i.c.v. injection of venlafaxine on carrageenan-induced paw hydrops
As illustrated in Fig. 2, i.c.v. disposal of venlafaxine ( 50 and 100 ?g/rat ) produced an attenuate paw hydrops formation as compared to the control group.
3.4. Consequence of venlafaxine on the MPO activity
The MPO activity of paw tissue was significantly increased at 4 H after injection of carrageenin. As shown in Fig. 3, venlafaxine ( 50 and 100 mg/kg i.p. ) significantly reduced MPO activity in the paw. The i.c.v. disposal of venlafaxine ( 50 and 100 ?g/rat ) besides decreased the MPO activity, compared to command group.
3.5. Consequence of venlafaxine on IL-1? concentration
As illustrated in Fig. 4, carrageenin injections significantly increased IL-1? concentration in the hind paw. Venlafaxine ( 50 and 100 mg/kg i.p. ) significantly reduced IL-1? degree. The i.c.v. disposal of venlafaxine ( 50 and 100 ?g/rat ) besides significantly attenuates production of IL-1? in the carrageenan-injected paws.
3.6. Consequence of venlafaxine on TNF-? concentration
As shown in Fig. 5, i.p. disposal of venlafaxine ( 50 and 100 mg/kg ) significantly reduced TNF-? coevals. The i.c.v. injection of venlafaxine ( 50 and 100 ?g/rat ) besides inhibited the coevals of TNF-? in the carrageenan-injected paw.
3.7. Consequence of yohimbine on the anti-inflammatory consequence of venlafaxine
Pretreatment with yohimbine ( 5 mg kg-1, i.p. ) 30 min prior to venlafaxine ( 50 milligram kilogram -1 ) did non change the anti-inflammatory consequence of venlafaxine ( Fig. 6 ) .
In the present survey at first, we demonstrated that i.p. and i.c.v. disposal of venlafaxine exhibit a important anti-inflammatory consequence in the carrageenan-induced paw hydrops in rats.
Our consequences showed that venlafaxine was effectual in rarefying paw hydrops in the redness induced by carrageenin.
Carrageenan-induced paw hydrops is one of the most often used theoretical accounts for the survey of redness and inflammatory strivings and is loosely used for rating the anti-inflammatory activity of different compounds. Release of azotic oxide and proinflammatory cytokines such as tumour mortification factor ( TNF ) -? , and interleukin-1? ( IL-1 ) are happen following carrageenin injections in to the hind paw ( Halici et al. , 2007 ; Nacife et al. , 2004 ) .
In the present survey the intervention of venlafaxine with the PMN cells migration has examined. Our consequences showed that both i.p. and i.c.v. disposal of venlafaxine caused a noticeable decrease in the infiltration of PMN leucocytes into the site of redness.
As mentioned above carrageenin injection besides aggravates the release proinflammatory cytokines such as TNF? and IL-1? ( Halici et al. , 2007 ;
Nacife et al. , 2004 ) . Cytokines have a critical function in the coevals and impairment of a assorted types of inflammatory disease including asthma, arthritis, and inflammatory intestine disease ( Codarri et al. , 2010 ; Feldmann and Maini, 2008 ; Ichinose and Barnes, 2004 ; Papadakis and
Targan, 2000 ) . Interestingly production of proinflammatory cytokines may be implicated in the pathogenesis of major depression ( Leonard, 2001 ; Maes et al. , 1995 ) . Therefore, the present survey was designed to find whether the anti-inflammatory consequence of venlafaxine could act upon the TNF-? and IL-1? coevals in the inflamed site. Our consequences showed that i.p. and i.c.v. injection of venlafaxine significantly reduced the IL-1? degrees in the carrageenan-injected paw tissues. Systemic and cardinal injection of venlafaxine besides decreased concentration of TNF-? .
Multiple lines of surveies besides have shown that cardinal mechanisms modulate peripheral redness.
[ 28–30 ] . It is besides good known that venlafaxine cause changes in cardinal noradrenaline and
[ 31–33 ] . Our consequences showed that i.c.v. disposal of venlafaxine attenuates the development of paw hydrops.
Therefore the consequence of venlafaxine on cardinal nervousnesss system to change neuroimmune interactions and/or sympathetic nervous system activity that affect the map of the immune system could be considered as one of the possible mechanisms of venlafaxine in fading of redness.
[ 34 ] . Besides it is possible that venlafaxine changes the activity of falling neural tracts, projecting from the encephalon to the spinal cord, taking to suppression of the peripheral nervus activity and dorsal root physiological reactions associated with the neurogenic constituent of redness [ 35, 36 ] .
Body of groundss showed the connexion between the redness and the coevals of hurting ( Marchand et al. , 2005 ) . Previous surveies have demonstrated that the suppression of proinflammatory cytokines coevalss, attenuates the hyperalgesia induced in different inflammatory strivings ( Ren and Dubner, 2010 ; Abbadie, 2005 ) . Therefore, it seems possible that the consequence of venlafaxine on PMN cells migration, TNF-? and IL-1? production may take part in its analgetic consequence.