[Experimental studies on the central analgesic effect of the non-steroidal anti-inflammatory drug carprofen in a sheep model -- preliminary results].
OBJECTIVE
To evaluate the effect of the non-steroidal anti-inflammtory drug carprofen on the lumbar cerebrospinal fluid (CSF) concentration of noradrenaline (NA) and serotonin (5-HT) in non-stimulated (Part I) and surgically stimulated (Part II) sheep.


METHODS
In a prospective controlled study the effects of a single intravenous (i. v.) bolus injection of 4 mg/kg carprofen (CARP; n = 14), 0.01 mg/kg fentanyl (FENT; n = 12) or 0.9 % saline solution (NaCl; n = 13) on lumbar CSF concentrations of NA and 5-HT were evaluated in non-stimulated sheep. In addition, CSF concentrations were evaluated in isoflurane-anaesthetised sheep at different time points T1 (30 min after i. v. treatment with 4 mg/kg carprofen [n = 8] or saline [n = 7], T2 (20 min of constant end-tidal isoflurane concentration of 2.4 %) and T3 (during stifle arthroscopy at 2.4 % end-tidal isoflurane).


RESULTS
CSF concentrations of NA (NaCl: 170.23 +/- 16.86 pg/ml [x +/- SEM], CARP: 200.79 +/- 28.94 pg/ml, FENT: 209.58 +/- 27.67 pg/ml; p = 0.524) and 5-HT (NaCl: 2752.46 +/- 413.87 pg/ml, FENT: 2969.08 +/- 684.05 pg/ml, CARP: 3232.93 +/- 713.93 pg/ml; p = 0.978) were not significantly different between the three treatment groups of non-stimulated sheep. In the anaesthetised sheep, mean CSF-5-HT at T3 (NaCl: 6670.25 +/- 313.63 pg/ml; CARP: 4080.80 +/- 539.59 pg/ml) was significantly increased compared to T1 (NaCl: 2818.4 +/- 1104.54 pg/ml, p < 0.001; CARP: 2926.13 +/- 818.66 pg/ml, p = 0.022) and T2 (NaCl: 2593.67 +/- 618.89 pg/ml, p = 0.002; CARP: 2724.13 +/- 395.39 pg/ml, p = 0.012) in both treatment groups. Moreover, mean CSF-5-HT at T3 in the saline group was significantly higher (p = 0.006) compared to the CARP-group. Unlike changes in CSF-5-HT, no significant changes in mean CSF-NA were recorded neither within nor between the two treatment groups.


CONCLUSIONS
During arthroscopy in isoflurane-anaesthetised sheep, surgical stimuli may significantly increase mean CSF-5-HT concentration. This effect can be attenuated by pre-treatment with 4 mg/kg carprofen intravenously. Therefore, the analgesic effects of carprofen may be at least in part mediated by central serotonergic mechanisms.
Otto
K
K
Zentrales Tierlaboratorium der Medizinischen Hochschule Hannover. otto.klaus@mh-hannover.de
Adams
H A
HA
D000701:Analgesics, Opioid / Q000494:pharmacology; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D001182:Arthroscopy; D002227:Carbazoles / Q000627:therapeutic use*; D002490:Central Nervous System / Q000187:drug effects*; D005283:Fentanyl / Q000494:pharmacology; D007275:Injections, Intravenous; D007530:Isoflurane; D009638:Norepinephrine / Q000134:cerebrospinal fluid; D012701:Serotonin / Q000134:cerebrospinal fluid; D012756:Sheep
D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D000894:Anti-Inflammatory Agents, Non-Steroidal; D002227:Carbazoles; D012701:Serotonin; D007530:Isoflurane; C007005:carprofen; D005283:Fentanyl; D009638:Norepinephrine