Nociception after intraperitoneal injection of a sodium pentobarbitone formulation with and without lidocaine in rats quantified by expression of neuronal c-fos in the spinal cord – a preliminary study

Abstract

SummaryAfter a search on Medline, it appears that intraperitoneal injection of sodium pentobarbitone is often used for anaesthesia and euthanasia of rodents. In the present pilot study in rats, spinal nociception after intraperitoneal injection of sodium pentobarbitone, with and without lidocaine, was examined by estimation of the number of c-fos-expressing neurones in the spinal dorsal horn. One group of rats received an intraperitoneal injection of 0.4 mL/kg sodium pentobarbitone (100 mg/mL; n ¼ 4). Another group of rats received a similar intraperitoneal injection of sodium pentobarbitone formulated with lidocaine 10 mg/mL (n ¼ 4); a control group received a similar intraperitoneal injection of 0.9% saline (n ¼ 4). After 3 h, the animals were re-anaesthetized and perfused with 4% formaldehyde, and the spinal cord was collected and processed by immunohistochemistry for stereological quantification of the number of neurones with c-fos-like immunoreactivity (FLI). Intraperitoneal injection of the sodium pentobarbitone formulation caused a significantly increased number of neurones with FLI in the spinal cord (39307247; mean7SEM; Po0.001) compared with the saline control group (7657131). The lidocaine added to the sodium pentobarbitone formulation significantly reduced the number to 27167393 (Po0.05). In conclusion, intraperitoneal injection of sodium pentobarbitone caused a significant increase in nociception which was lowered by adding lidocaine to the formulation, although it was still significantly higher than the control level. Further studies are needed with the aim of optimizing the lidocaine concentration and also to examine the effect of the combination of lidocaine with a long-acting local anaesthetic agent, e.g. bupivacaine.

The Effects of Insufflation Conditions on Rat Mesothelium

“…We used inhaled isoflurane to avoid any direct irritation within the peritoneum from the anaesthetic whereas Hazebroek et al used intraperitoneal pentobarbitone administered every 30 min. Pentobarbitone is known to have irritant effects [35] which may have significantly contributed to the mesothelial damage. This hypothesis is supported by the fact that the group with mechanical abdominal wall lifting in the study showed similar damage to the three insufflation groups, indicating that pneumoperitoneum was not the cause of the mesothelial damage.…”

Biomimetic electrospun coatings increase the in vivo sensitivity of implantable glucose biosensors

“…However, we observed repeated dosing with lower volume of pentobarbitone to be safer at maintaining anesthesia, because the margin between anesthetic and lethal doses for pentobarbitone is very narrow . However, concerns are raised because of the low pH of the pentobarbitone solution . Due to pain that may be caused by the low pH, use of pentobarbitone as an anesthetic is generally discouraged unless it was for nonrecovery procedures.…”

“…34 However, concerns are raised because of the low pH of the pentobarbitone solution. 35 Due to pain that may be caused by the low pH, use of pentobarbitone as an anesthetic is generally discouraged unless it was for nonrecovery procedures. Similarly, the use isoflurane as an anesthetic for glucose tolerance test is discounted since it offsets the glycemic profile.…”

Refinement of intraperitoneal injection of sodium pentobarbital for euthanasia in laboratory rats (Rattus norvegicus)

“…Current guidelines do not indicate a specific dose of sodium pentobarbital for euthanasia, although 200 mg/kg or 3 times the anesthetic dose have been suggested [5]. There are several potential drawbacks associated with IP PB injection, including misinjection, variability in effect and pain [7,[16][17][18][19][20][21][22]. An important factor contributing to variability of drug effect (speed of onset and success) is misinjection, with deposition of injectate into intra-abdominal fat, abdominal viscera or the subcutaneous space.…”

“…Specifically, exhibition of writhing (defined as the contraction of the abdomen and extension of the hind legs), grossly visible inflammation of abdominal viscera at necropsy and a measurable increase in spinal cord cFos have been reported following IP injection of pentobarbital [16,17,21,22].…”