Thermal Gradient Ring Reveals Thermosensory Changes in Diabetic Peripheral Neuropathy in Mice

Diabetic peripheral neuropathy (DPN) includes symptoms of thermosensory impairment, which are reported to involve changes in the expression or function, or both, of nociceptive TRPV1 and TRPA1 channels in rodents. In the present study, we did not find changes in the expression or function of TRPV1 or TRPA1 in DPN mice, although thermal hypoalgesia was observed in a murine model of DPN or TRPV1–/– mice with a plantar test, which specifically detects temperature avoidance. With a Thermal Gradient Ring in which mice can move freely in a temperature gradient, temperature preference can be analyzed, and we clearly discriminated the temperature-dependent phenotype between DPN and TRPV1–/– mice. Accordingly, we propose approaches with multiple behavioral methods to analyze the progression of DPN by response to thermal stimuli. Attention to both thermal avoidance and preference may provide insight into the symptoms of DPN.

Role of Muscarinic Receptors in Hypoalgesia Induced by Crocin in Neuropathic Pain Rats

Objective. Crocin as an important constituent of saffron has antineuropathic pain properties; however, the exact mechanism of this effect is not known. The aim of this study was whether the hypoalgesic effect of crocin can be exerted through muscarinic receptors. Materials and Methods. In the present project, 36 male Wistar rats (200 ± 20 g) were used. Animals randomly divided into six groups (sham, neuropathy, neuropathy + crocin, neuropathy + atropine 0.5 mg/kg, neuropathy + atropine 1 mg/kg, and neuropathy + atropine 1 mg/kg + crocin). Neuropathy was induced by the chronic constriction injury (CCI) method on the sciatic nerve. Crocin and atropine was administered intraperitoneally during 14 days following the 14th day after surgery. Pain response was detected every three days, two hours after each injection and 3 days following last injection. Mechanical allodynia and thermal hyperalgesia were detected using the Von Frey filaments and plantar test device, respectively. Results. CCI significantly reduced the paw withdrawal response to mechanical and thermal stimulus ( P < 0.01 and P < 0.05 , respectively). Crocin therapy significantly reduced mechanical allodynia and thermal hyperalgesia induced by CCI ( P < 0.05 ). Atropine pretreatment significantly blocked the hypoalgesic effect of crocin ( P < 0.05 in mechanical allodynia and P < 0.01 in thermal hyperalgesia). Fourteen days administration of atropine alone at a dose of 0.5 mg/kg but not 1 mg/kg significantly reduced CCI-induced mechanical allodynia at day 30 after surgery. Conclusion. Crocin significantly decreased CCI-induced neuropathic pain. The hypoalgesic effect of crocin was blocked by atropine pretreatment, which indicates an important role for muscarinic receptors in the effect of crocin.

EFEKTIVITAS ANALGETIK EKSTRAK ETANOL AKAR ALANG-ALANG (Imperata cylindrica (L) Beauv ) PADA MENCIT PUTIH JANTAN

Pain is an unpleasant sensory and emotional experience due to tissue damage, either actual or potential or described in the form of damage. Provision of therapeutic doses of analgesics relieve pain or suppress. Plants Imperata cylindrica L. Beauv empirically used as traditional medicine. The purpose of this study to know the analgetic effect of root ethanol extract of alang-alangImperata cylindrica L. Beauv. This study was done by infra red (IR) plantar test method with a wavelength of 96 nm. Twenty male mice were divided into 4 groups. Three groups were given ethanol extract of Imperata cylindrica L. Beauv branches at a doses of 15 mg/kg bb, 30 mg/kg bb 60 mg/kg bb and one group was given 0,5% CMC Na (control) orally. After that, the time (second) hold infra red induction of pain every 10 minutes to 60 minutes. The data obtained were processed using one-way analysis of variance (ANOVA) and followed test the level of 95%. The results of phytochemical screening Imperata cylindrica L. Beauv is alkaloid, flavonoid, and steroid/triterpenoid. Ethanol extract Imperata cylindrica L. Beauv dose of 15 mg/kg bb average induction able to withstand pain of 12,86; 14,34; 15,44; 19,2; 17,52; 15,42 second, the dose of 30 mg/kg bb 13,6; 17,08; 19,82; 18,44; 16,9; 16,48 second, and a dose of 60 mg/kg bb 16,96; 18,9; 18,94; 22,14; 18,0; 17,26 second. Pain is an unpleasant sensory and emotional experience due to tissue damage, either actual or potential or described in the form of damage. Provision of therapeutic doses of analgesics relieve pain or suppress. Plants Imperata cylindrica L. Beauv empirically used as traditional medicine. The purpose of this study to know the analgetic effect of root ethanol extract of alang-alangImperata cylindrica L. Beauv. This study was done by infra red (IR) plantar test method with a wavelength of 96 nm. Twenty male mice were divided into 4 groups. Three groups were given ethanol extract of Imperata cylindrica L. Beauv branches at a doses of 15 mg/kg bb, 30 mg/kg bb 60 mg/kg bb and one group was given 0,5% CMC Na (control) orally. After that, the time (second) hold infra red induction of pain every 10 minutes to 60 minutes. The data obtained were processed using one-way analysis of variance (ANOVA) and followed test the level of 95%. The results of phytochemical screening Imperata cylindrica L. Beauv is alkaloid, flavonoid, and steroid/triterpenoid. Ethanol extract Imperata cylindrica L. Beauv dose of 15 mg/kg bb average induction able to withstand pain of 12,86; 14,34; 15,44; 19,2; 17,52; 15,42 second, the dose of 30 mg/kg bb 13,6; 17,08; 19,82; 18,44; 16,9; 16,48 second, and a dose of 60 mg/kg bb 16,96; 18,9; 18,94; 22,14; 18,0; 17,26 second.

Aktivitas Analgetik Ekstrak Etanol Daun Pugun Tanoh (Picria Fel-Terrae Lour) Pada Mencit (Mus Musculus)

Pugun Tanoh (Picria fel-terrae Lour) telah digunakan dalam pengobatan tradisional untuk mengatasi sakit perut dan inflamasi. Kajian ilmiah perlu dilakukan untuk membuktikan khasiat pugun tanoh tersebut khususnya sebagai analgetik. Pengujian aktivitas analgetik ekstrak etanol daun P. fel-terrae dilakukan menggunakan metode plantar tes infrared. Analisis dilakukan dengan membandingkan waktu yang dibutuhkan hewan uji untuk menahan induksi panas dari infrared (IR) pada panjang gelombang 96 nm, setelah pemberian ekstrak dengan dosis 25, 50 dan 100 mg/kg bb. Morfin 10 mg/kg bb dan antalgin 300 mg/kg bb digunakan sebagai kontrol positif. Kelompok kontrol negatif hanya menerima CMC-Na 0,5%. Pengamatan dilakukan selama 90 menit. Ekstrak etanol daun P. fel-terrae menunjukkan efek analgetik jika dibandingkan dengan kelompok kontrol negatif (P>0.05). Nilai AUC (Area Under Curve) waktu respon terhadap nyeri semakin tinggi dengan meningkatnya dosis. Ekstrak pada dosis 100 mg/kg bb menunjukkan aktivitas paling tinggi dengan efek analgetik yang lebih baik dari antalgin 300 mg/kg bb (p < 0,05) tetapi memiliki efek analgetik yang sama dengan morfin 10 mg/kg bb (p > 0,05). Ekstrak etanol daun P. fel-terrae mempunyai efek analgetik dan berpotensi untuk dikembangkan menjadi fitofarmaka. Pugun Tanoh (Picria fel-terrae Lour) has been used in folk medicine for the treatment of stomach ache and inflammation. The scientific study needs to be done to prove the activity of pugun tanoh especially as analgesic. The evaluation of analgesic activity of ethanol extract of pugun tanoh leaves was conducted using plantar-test infra red method. Analysis was perfomed by comparing the the duration of test animals to resist heat induction from infrared (IR) at a wavelength of 96 nm after being treated with extract at doses of 25, 50 dan 100 mg/kg bw. Morphine 10 mg/kg bwand antalgin 300 mg/kg bwwere used as positive control. Control negative group only received 0.5% Na CMC. The observation was performed for 90 minutes. The ethanol extract of pugun tanoh leaves showed analgesic effect as compared to negative control group (P<0.05). AUC (Area Under Curve) value of duration to resist pain increased as the dose increased. The extract at dose of 100 mg/kg bw displayed higher analgesic activitythan antalgin 300 mg/kg bw (p < 0,05) but was comparable with morphine10 mg/kg bw (p > 0,05). The ethanol extract of P. fel-terraeleaf possesses analgesic activity and thus can be developed into phytopharmaca

Experimental Study of the Analgesic Effect of the Antidepressant Escitalopram

Background: Antidepressants have been found to possess antinociceptive and analgesic properties and are prescribed in the treatment of chronic pain. Aim: To evaluate the antinociceptive properties of escitalopram after a single administration. Materials and methods: Forty Wistar rats were used in the study. They were divided into 5 groups (n=8) treated with saline solution (control group), metamizole (150 mg/kg b.w.), escitalopram (5, 10 and 20 mg/kg b.w.) intraperitoneally. The nociceptive tests we used employed thermal (hot plate and plantar test), mechanical (analgesimeter) and chemical (formalin test) stimuli. Criteria for analgesic effect were increased latency in hot plate, plantar test, analgesimeter and decreased paw licking time in formalin test. Results: The reference analgesic metamizole showed significant analgesic effect in all tests excluding the first phase with formalin. Escitalopram in doses of 5 and 20 mg/kg b.w. increased paw withdrawal latency in analgesimeter at 2 hours compared to control. Escitalopram in a dose of 5 mg/kg b.w. increased the duration of the stay on the hot plate at 1 hour, while doses of 10 and 20 mg/kg b.w. significantly increased this indicator at 1 and 3 hours in comparison to the saline treated group. In the plantar test, escitalopram in all used doses significantly increased the nociceptive response latency compared to control. A dose of 5 mg/kg b.w. decreased hind paw licking time during phase 1 of the formalin test, whereas doses of 10 and 20 mg/kg b.w. decreased phase 2 licking time compared to the control group. Conclusion: The antidepressant escitalopram has analgesic properties but they are not dose- or time-dependent.

INFLUENCE OF GENDER AND OBESITY ON ANALGESIC MODULATION OF TRAMADOL IN RATS

Objective: The objective of this study was to investigate the influence of gender and obesity on analgesic modulation of tramadol in Wistar rats.Methods: This study was carried out in two sets of experiments. In Set I experiment - 48 rats (body weight ≤150 g), 24 each male and female rats were randomly divided into two groups (n=6/group) (Group I - Control; 0.9% NaCl; 1 ml/kg/day i.p. and Group II - Tramadol 10 mg/kg/day i.p.) for each nociception model - plantar test and acetic acid-induced writhing test. The treatment duration was of 5 days. On the last day of treatment (i.e., on the 5th day), paw withdrawal latency (PWL) was assessed using plantar test, and writhing movements were observed following administration of 0.8% acetic acid; 10 ml/kg i.p. Set II experiment was repeated like Set I experiment among rest 48 high-fat diet-fed rats (body weight ≥300 g).Results: For both males and females, PWL was significantly decreased (p<0.05) in obese control groups compared to lean control groups. A number of writhing movements were significantly increased (p<0.01 for males and p<0.001 for females) in obese control groups compared to lean control groups. In tramadol-treated obese rats, PWL was significantly decreased (p<0.01 for males and p<0.05 for females), and number of writhing movements were significantly increased (p<0.01 for both males and females) in comparison with the tramadol-treated lean rats.Conclusion: The present study revealed that obese female rats experience more pain sensation to noxious stimuli compared to lean male rats and also the analgesic effect of tramadol is more pronounced in lean male rats compared to obese female rats.

CORRELATION OF GENDER AND LEPTIN WITH ANALGESIC EFFECT OF TRAMADOL IN RATS

Objective: The objective of the study was to investigate the correlation of gender and serum leptin level with analgesic modulation of tramadol in Wistar rats.Methods: A total of 48 Wistar rats (body weight 100–150 g), 24 each male and female Wistar rats were randomly divided into two groups (n=6/group) (Group I - Control- 0.9% NaCl; 1 ml/kg/day i.p. and Group II - Tramadol 10 mg/kg/day i.p.) for each nociception model - plantar test and acetic acid induced writhing test. The treatment duration was of 5 days. Paw withdrawal latency (PWL) was assessed using plantar test and writhing movements were observed following administration of 0.8% acetic acid; 10 ml/kg i.p.Results: PWL was significantly decreased (p<0.001) and both number of writhing movements and serum leptin concentrations were significantly increased (p<0.001) in female control group compared to male control group. In tramadol treated female rats, PWL was significantly decreased (p=0.005) and both number of writhing movements and serum leptin concentrations were significantly increased (p<0.001) in comparison with the tramadol treated male rats. PWL was negatively correlated with serum leptin concentration (Pearson correlation coefficient= −0.826, two-tailed significance= 0.000), and writhing movements were positively correlated with serum leptin concentration (Pearson correlation coefficient= 0.505, two-tailed significance= 0.012).Conclusions: The present study revealed that female rats have more serum leptin concentration than male rats which could be one of the possible reasons for having more pain sensitivity to noxious stimuli in female rats compared to male rats. Tramadol treatment at the dose of 10 mg/kg for 5 days has decreased serum leptin level in rats which might be one of the additional mechanisms of tramadol to reduce pain.

Η επίδραση της κεταμίνης σε λειτουργίες του ιππόκαμπου

Εισαγωγή: H κεταμίνη μέχρι σήμερα έχει μελετηθεί εκτεταμένα, κλινικά και εργαστηριακά, με σκοπό να καθοριστούν τόσο ο μηχανισμός δράσης της όσο και το καταλληλότερο πεδίο εφαρμογής της στην κλινική πράξη. Η κύρια φαρμακολογική ενέργεια της κεταμίνης οφείλεται στην ανταγωνιστική δράση της στους υποδοχείς του N-μέθυλο-D-ασπαραγινικού οξέος (NMDA) επιφέροντας αναλγητική και αναισθητική δράση. ‘Ερευνες έχουν αποκαλύψει τον σημαντικό ρόλο των NMDA υποδοχέων στο μηχανισμό του πόνου. Ο ιππόκαμπος που θεωρείται το κέντρο της μνήμης στο κεντρικό νευρικό σύστημα (ΚΝΣ),είναι ιδιαίτερα ευαίσθητος στα νευροτοξικά φάρμακα. Επίσης, ο ιππόκαμπος είναι η περιοχή του εγκεφάλου που έχει μελετηθεί περισσότερο από κάθε άλλη για τον σημαντικό ρόλο των NMDA υποδοχέων στη συναπτική πλαστικότητα, στη μνήμη και τη μάθηση.Σκοπός της μελέτης: Η διαχείριση των ασθενών με νευροπαθητικό πόνο παρουσιάζει πολλές δυσκολίες και η αποτελεσματική θεραπεία τους αποτελεί πρόκληση στην κλινική πράξη. Σκοπός της παρούσας διατριβής είναι αφενός να μελετήσει την αποτελεσματικότητα της χορήγησης υποαναισθητικής δόσης κεταμίνης στην ελάττωση του νευροπαθητικού πόνου και αφετέρου να συνεισφέρει στην αποσαφήνιση των ανεπιθύμητων ενεργειών που προκαλούνται -κατά κύριο λόγο στη λειτουργικότητα του ιπποκάμπου και κατ' επέκταση στις διεργασίες μνήμης- από τη χρόνια χρήση αναλγητικών δόσεων κεταμίνης. Με δεδομένη τη συσχέτιση που φαίνεται να υπάρχει μεταξύ διαβητικής νευροπάθειας και χρόνιου νευροπαθητικού πόνου, η μελέτη όλων των ανωτέρω στηρίχτηκε σε πειραματικά πρωτόκολλα που εφαρμόστηκαν και σε διαβητικές ομάδες επίμυων.Υλικό-Μέθοδος: Για την διεξαγωγή του πειράματος χρησιμοποιήθηκαν συνολικά 56 επίμυες (Wistar), ηλικίας 10-12 εβδομάδων και βάρους 250 έως 320 γραμμαρίων. Στην πρώτη φάση (Φάση Α) πραγματοποιήθηκαν δοκιμασίες με σκοπό να προσδιοριστεί αν η χορήγηση κεταμίνης σε φυσιολογικούς και διαβητικούς επίμυες μετά από πρόκληση νευροπαθητικού πόνου έχει αναλγητική επίδραση. H πρόκληση περιφερικού νευροπαθητικού πόνου πραγματοποιήθηκε με τη μέθοδο της αξονότμησης-σύνθλιψης (crush) του ισχιακού νεύρου. Οι επίμυες χωρίστηκαν αρχικά σε 2 ίσες ομάδες. Την ομάδα ελέγχου (N/S 0,9%) και την πειραματική ομάδα (κεταμίνη 5 mg/kg). Στη συνέχεια οι επίμυες κάθε ομάδας χωρίστηκαν τυχαία σε τέσσερις υποομάδες. Tους φυσιολογικούς (n=7), τους διαβητικούς(n=7), τους φυσιολογικούς οι οποίοι υποβλήθηκαν σε χειρουργείο αξονότμησης του ισχιακού νεύρου (n=7) και τους διαβητικούς οι οποίοι υποβλήθηκαν σε χειρουργείο αξονότμησης του ισχιακού νεύρου (n=7). Σε όλους τους επίμυες έγινε μελέτη της μηχανικής αλλοδυνίας με το Von Frey test και της θερμής υπεραλγησίας με το Hot Plate test. Ακολούθησε η δεύτερη φάση του πειράματος (Φάση Β) κατά την οποία μελετήθηκε η επίδραση της χρόνιας χορήγησης κεταμίνης στη μνήμη των επίμυων, μέσω της δοκιμασίας αναγνώρισης καινοφανούς αντικειμένου (Novel Object Recognition Task).Αποτελέσματα: Κατά τον έλεγχο της μηχανικής αλλοδυνίας (Von Frey test) δεν παρατηρήθηκε στατιστικά σημαντική διαφορά μεταξύ των φυσιολογικών, φυσιολογικών/crush και διαβητικών/ crush επίμυων όταν αυτοί τέθηκαν σε σύγκριση με τις αντίστοιχες ομάδες στους οποίους όμως είχε χορηγηθεί κεταμίνη. Κατά τον έλεγχο θερμικής υπεραλγησίας (Plantar test) παρατηρήθηκε στατιστικά σημαντική διαφορά στο χρόνο αντίδρασης των φυσιολογικών ποντικιών, των crush ποντικιών και των crush/διαβητικών ποντικιών έναντι των φυσιολογικών ποντικιών, των crush ποντικιών και των crush/διαβητικών ποντικιών στα οποία είχε χορηγηθεί κεταμίνη. Στη δοκιμασία ελέγχου μνήμης (Novel Object Recognition Test) και πιο συγκεκριμένα στην Γ΄ φάση (έλεγχος βραχυπρόθεσμης μνήμης) τα φυσιολογικά ποντίκια που έχουν λάβει κεταμίνη εμφανίζουν υψηλότερη τιμή έναντι των φυσιολογικών ποντικιών. Στις ομάδες των διαβητικών ποντικιών, των crush ποντικιών και των crush/διαβητικών ποντικιών έναντι των αντίστοιχων ομάδων που έχουν λάβει κεταμίνη δεν υπάρχουν στατιστικά σημαντικές διαφορές μεταξύ τους σε καμία φάση της δοκιμασίας.Συμπεράσματα: Βάση των αποτελεσμάτων που προέκυψαν η μηχανική αλλοδυνία δεν αντιμετωπίζεται αποτελεσματικά με τη χορήγηση κεταμίνης Η μόνη στατιστικά σημαντική διαφορά που διαπιστώθηκε αφορούσε τους διαβητικούς -υπό την επίδραση κεταμίνης- επίμυες στους οποίους απαιτήθηκαν σημαντικά υψηλότερες τιμές ασκούμενης πίεσης κατά τη δοκιμασία Von Frey προκειμένου να εκδηλωθεί αντίδραση απόσυρσης. Η κεταμίνη μπορεί να αποτελέσει ικανή φαρμακευτική επιλογή στις περιπτώσεις ασθενών με χρόνιο νευροπαθητικό άλγος χωρίς ωστόσο να προκρίνεται σε σημαντικό βαθμό η επιλογή της έναντι των λοιπών επιλογών που χρησιμοποιούνται στην καθημερινή κλινική πράξη. Μετά τη χορήγηση κεταμίνης οι φυσιολογικοί, φυσιολογικοί/crush και οι crush/διαβητικοί επίμυες παρουσίαζαν μεγαλύτερους χρόνους εκδήλωσης αντίδρασης (σε στατιστικά σημαντικό βαθμό) στη δοκιμασία θερμικής υπεραλγησίας. ‘Οσον αφορά τη δοκιμασία αναγνώρισης καινοφανούς δεν προέκυψαν στατιστικώς σημαντικές διαφορές μεταξύ των επίμυων που έλαβαν κεταμίνη και εκείνων που δεν έλαβαν.

Local Silver Nanoparticles Administration Promotes Inflammation and Hyperalgesia in Rats

Silver has no known function in the organism. However, nanosilver has the highest degree of commercialization of all nanomaterials used in healthcare. The aim of this study was to assess the potential deleterious effect of local nanosilver administration in an animal model. Wistar rats received a subcutaneous injection (hind paw) of either 500ppm nanosilver (group S1), 20ppm nanosilver (group S2) or saline (control group). Animals were tested by means of plantar test, analgesy-meter and plethysmometer. 24 h after the administration, l-carrageenan was injected (same site), which lead to localized inflammation. The above-mentioned assessments were performed repeatedly until 24 h after l-carrageenan administration. 24 h after colloidal silver administration, both S1 and S2 groups had a significantly higher sensibility to mechanical stimuli. 48 h after colloidal silver administration, the S1 group had a significantly higher sensibility to thermal stimuli. Paw edema was more pronounced in the treatment groups in the first 30 h after the nanosilver injection. Local subcutaneous nanosilver administration leads to an increased inflammatory response and to hyperalgesia. Considering the constant increase in nanosilver�s biomedical use, the current paper sends a clear warning for the need of urgent more in-depth research on the matter.

Analgesic Activity Test 2- (3- (chloromethyl) Benzoiloksi) Benzoate and 2- (4- (chloromethyl) Benzoiloksi) Benzoate on Male Wistar Rats with Plantar Test Method

The new compounds of salicylic acid derivatives, 2- (3- (chloromethyl) benzoiloksi)benzoic acid and 2-(4-(chloromethyl)benzoiloksi) benzoate was synthesized to produce a greater analgesic activity and lower stomach irritation from salicylic acid. 2-(4-(chloromethyl) benzoiloksi)benzoic acid and 2-(3-(chloromethyl)benzoiloksi) benzoate was synthesized by Schotten-Baumann acylation reaction. In this study, the analgesic test activity with plantar test method. The compound was given to test animals in doses of 12.5; 25; 50; 100; and 200 mg.kg-1. Analgesic activity was determined by the response time of mice to pain infra-red heat. The percentage is calculated by the mean pain barrier time response to pain. The results showed percentation of pain barrier: 74.28%; 105.58%; 110.58%; 115.29%; and 175.87% after administration of the compound 2-(4-(chloromethyl) benzoiloksi) benzoate at doses of 12.5; 25; 50; 100; and 200 mg.kg-1, respectively. The results of calculations percent pain barrier 2-(3-(chloromethyl)benzoiloksi) benzoate, obtained 85.30%; 92.48%; 124.96%; 180.36%; and 208.01% consecutive for the doses compound of 12.5; 25; 50; 100; and 200 mg.kg-1. Five doses of acetyl salicylic acid ranging from 12.5 mg. kg-1 to 200 mg.kg-1 resulted in percent pain barrier as follows: 26%; 34.34%; 45.68%; 60.38% and 114.12%. This study indicates that 2-(3-(chloromethyl)benzoiloksi)benzoic acid and 2-(4-(chloromethyl)benzoiloksi) benzoate are capable of producing higher analgesic activity than acetyl salicylic acid. Keywords: analgesic, benzoate, plantar test method