Different Effects of Testosterone on Acute and Chronic Pain in Gonadectomized Male Rats

ABSTRACT: Introduction & Objective: Nociception and behavioral responses to noxious stimuli are different in males and females. It seems that these differences are due to the effects of sex hormones on the pain mechanisms. The aim of the current study was to evaluate the effect of testosterone administration on nociception by formalin test in gonadectomized rats. Material & Methods: In this study 32 male wistar rats were divided into four groups (n=8) the control rats without receiving any drug or surgical operation, the sham – operated animals with surgical stress, the gonadectomized rats receiving 0.5 ml vehicle (olive oil ) i.p., and the gonadectomized rats receiving testosterone enantate (6 mg/100 gr body weight in 0.5 ml vehicle i.p.). On the sixth day after gonadectomy operation, formalin test was done in all rats. Pain scores in formalin test were statistically analyzed by SPSS and ANOVA. Results: The results showed that testosterone caused an increase in pain score in acute phase of formalin test in gonadectomized rats compared with sham-operated group (p<0.001). However, pain score in chronic phase was significantly reduced in testosterone received rats (p<0.001). Conclusion: It can be concluded that testosterone increases nociception in acute phase of formalin test in gonadectomized rats. On the other hand, testosterone relieved pain during chronic phase. Anti-nociceptive effects of testosterone in chronic phase may be through central nervous system by interacting with endogenous pain modulatory system

Effect of Testosterone on Carrageenone Induced Inflammation in Gonadectomized Male Rats

ABSTRACT: Introduction & Objective: Different nociceptive and inflammatory responses to noxious stimuli in male and female animals imply that sex hormones may affect on inflammatory factors, induction and intensity of the inflammation. The aim of the current study was to evaluate the effect of testosterone administration on carrageenone induced inflammation in gonadectomized male rats. Materials & methods: Forty male Wistar rats were divided into four groups (n=8). 1-The control rats without receiving any drug or surgical operation. 2-The sham – operated animals with surgical stress. 3-The gonadectomized rats, receiving 0.5 ml vehicle (olive oil) i.p. 4-The gonadectomized rats, receiving testosterone enantate (6 mg/100 gr body weight in 0.5 ml vehicle i.p.). At the sixth day of gonadectomy operation, inflammation was induced by injection of 1% carrageenone in the right hind paw of rats. Edematous paw volume as an index of inflammation was determined by immersing it into the mercury container. Weight of paw in the mercury was measured and then the paw volume was calculated in relation to specific gravity of mercury (13.6gm/ml). Data were statistically analyzed by SPSS software using ANOVA. Results: The results showed that edematous paw volume significantly was reduced in testosterone enantate administrated gonadectomized rats compared to the control group (P<0.01). Conclusion: It can be concluded that high dose of testosterone causes attenuation of inflammatory response. The testosterone anti-inflammatory effect is probably due to inhibition of inflammatory factors (Interleukins) production or decrease in receptors of inflammatory factors. Keywords: Testosterone, Carrageenone, Inflammation, Rat

Effect of C-peptide on Cognitive Dysfunction and Neuronal Apoptosis Caused by beta amyloid 1-42 in Diabetic Rats

Background & Aim: Alzheimer disease is characterized by a progressive loss of memory. Its prevalence in diabetic patients is nearly twice in comparison of others. Recent findings suggest that C-peptide replacement in type 1 diabetes exerts beneficial effects on diabetic rats. We examined the effects of C-peptide on cognitive dysfunction and neuronal apoptosis caused by Aβ 1-42 on working memory in Streptozotocin induced diabetic rats. Methods: In the present experimental study which was carried out in 2009 at Shiraz University of Medical Sciences, 50 male Sprague Dawley rats (230-300 gr) were divided into five groups: control, type 1 diabetic, diabetic groups receiving C-peptide, diabetic group receiving beta amyloid, diabetic group receiving beta amyloid and c-peptide. The Neuronal apoptosis were assessed with tunnel staining. Diabetes was induced with IV injection of Streptozotocin (60 mg/kg). Twenty six days after the onset of diabetes, behavioral tests were conducted for three days. For data analysis, the Tukey and One way ANOVA tests were used. Results: In comparison to control group, in all diabetic groups working memory impairments was observed (P<0.05), but Aβ 1-42 caused severe deficits in the working memory (P<0.001) and C-peptide could significantly decrease the impairment (P<0.05). Only the diabetic beta amyloid group showed significant amount of tunnel positive neuron (P<0.05) and c-peptide replacement significantly decreased the amount of these cells (P<0.05). Conclusion: C-peptide could significantly decrease memory impairment and neuronal apoptosis among diabetic rats

Comparison of tarnish level in two types of high- copper dental amalgams with lathe-cut and spherical particles produced in Iran

&quot;nAbstract: There are two types of high-copper dental amalgams produced in Iran; Cinalloy (lathe-cut particles) and Cinalux (spherical particles). Tarnish is one of the disadvantages of dental amalgam, which precedes corrosion, and in fact it means real destruction of restorative materials. The purpose of this study was to compare the extent of tarnish in Cinalux and Cinalloy amalgams. 32 patients, with at least two carious or poorly restored teeth were selected. Then, each tooth was restored with one of these two types of dental amalgams. The restorations were polished after 24 hours and patients were followed up after 9 months. The restorations were categorized in four groups of no change, one plus (1-30%), two plus (30-60%) and three plus (more than 60%) according to the level of discoloration. The results showed that the level of tarnish in Cinalux group was significantly less than Cinalloy group. The mean of tarnish for Cinalloy and Cinalux was 2.09&amp;plusmn;0.59 and 1.72&amp;plusmn;0.68 respectively. In addition, statistical analysis showed that there was no significant relationship between tarnish and Oral hygiene, smoking, operator or type and place of restoration

Effect of gamma ray (25 gray) on spermatogenesis and role of epinephrine as a protector in adult rat

Background: Since human being is exposed to gamma ray during radiotherapy and some diagnostic tests, studying radiation and radioprotection is necessary. We evaluated the effects of gamma ray (25 gray) on spermatogenesis process and the role of epinephrine as a protector in adult rat. Materials and Methods: In an experimental study, 120 Wistar rats were divided into 4 groups as follows: 1-Receiving epinephrine 2- receiving saline (Control) 3-exposed to gamma ray and receiving epinephrine, 4-exposed to gamma ray and receiving saline. Epinephrine was injected subcutaneously to abdominal area in a sub lethal dose (1 ml/kg). The animals were exposed to gamma radiation by a gamma ray producing apparatus capable of producing 25 gray gamma radiation. Then testes were removed and spermatogonia cells, primary spermatocytes, spermatid cells, spermatozoids and interstitial cells were counted. Results: According to the findings in gamma ray group the somniferous tubes were separated from each other and their epithelium showed a significant (p<0.05) reduction in the number of spermatogonia, spermatid and sperm cells. These changes were associated with an increase in the number of primary spermatocytes. These were not seen in the group received epinephrine. Conclusion: It seems that epinephrine via blood vessel constriction can act as a protector for gamma radiation damages through free radical reduction