The antinociceptive and antihyperalgesic effects of topical propofol on dorsal horn neurons in the rat

Comparison of postoperative awakening between ciprofol and propofol in elderly patients undergoing hip replacement surgery: a single-blind, randomized, controlled trial

BACKGROUND

The aim of this paper was to compare the impact of continuous infusion of ciprofol versus propofol on postoperative awakening in elderly patients following hip replacement surgery.

METHODS

Patients were randomized into two groups (N.=45 each): the ciprofol group and the propofol group. The ciprofol group received ciprofol for anesthesia induction and maintenance, while the propofol group underwent anesthesia induction and maintenance using propofol. The primary outcome was awakening time. Secondary outcomes included spontaneous breathing recovery time, extubation time, time to modified Aldrete Score ≥9, modified observer's assessment of alertness/sedation (MOAA/S) scores, anesthetic dosage, volume of fluid replacement, urine output and administration of vasoactive drugs.

RESULTS

The Ciprofol group exhibited a significantly prolonged awakening time (11.0±6.4 min vs. 7.4±4.3 min, P=0.003), spontaneous breathing recovery time (9.9±6.3 min vs. 5.9±4.3 min, P=0.001), and extubation time (12.0 [8.0-16.0] min vs. 8.5 [6.0-11.0] min, P=0.005), and reduced requirement for intraoperative fluid replacement (728.9±254.2 mL vs. 908.3±287.5 mL, P=0.003), increased urine output (235.1±102.1 mL vs. 173.5±106.2 mL, P=0.007), decreased likelihood of vasoactive drug administration (15/30 vs. 28/14, P=0.002). No significant differences were observed between the two groups in terms of reaching a modified Aldrete Score ≥9, MOAA/S scores at 0, 5, 15, or 30 minutes post-extubation, or occurrence of adverse reactions (P>0.05). The dosage of remifentanil was significantly higher in the ciprofol group [5.4 (2.7-7.4) μg·kg-1·h-1 vs. 3.4 (1.9-4.3) μg·kg-1·h-1, P=0.004], with a mean maintenance dose of ciprofol at 0.8 mg·kg-1·h-1 (range: 0.5 to 1.2 mg·kg-1·h-1).

CONCLUSIONS

Compared to propofol, the administration of ciprofol in elderly patients following hip replacement surgery is associated with prolonged awakening time, spontaneous breathing recovery time, and extubation. The average intravenous maintenance dosage of ciprofol in geriatric patients under general anesthesia was 0.8 mg·kg-1·h-1.

How Is the Nociceptive Withdrawal Reflex Influenced by Increasing Doses of Propofol in Pigs?

The nociceptive withdrawal reflex (NWR) is a physiological, polysynaptic spinal reflex occurring in response to noxious stimulations. Continuous NWR threshold (NWRt) tracking has been shown to be possibly useful in the depth of anesthesia assessment. The primary aim of this study was to describe how propofol modulates the NWRt over time in pigs. Five juvenile pigs (anesthetized three times) were included. An intravenous (IV) infusion of propofol (20 mg/kg/h) was started, and boli were administered to effect until intubation. Afterwards, the infusion was increased every ten minutes by 6 mg/kg/h, together with an IV bolus of 0.5 mg/kg, until reaching an electroencephalographic suppression ratio (SR) of between 10% and 30%. The NWRt was continuously monitored. For data analysis, the time span between 15 min following intubation and the end of propofol infusion was considered. Individual durations of propofol administration were divided into five equal time intervals for each pig (TI1-TI5). A linear regression between NWRt and TI was performed for each pig. Moreover, the baseline NWRt and slopes of the linear regression (b1) were compared among days using a Friedman Repeated Measures Analysis of Variance on Ranks. The NWRt always increased with the propofol dose (b1 = 4.71 ± 3.23; mean ± standard deviation). No significant differences were found between the baseline NWRt and the b1 values. Our results suggest that the NWRt may complement the depth of anesthesia assessment in pigs receiving propofol.

Type of anesthesia and quality of recovery in male patients undergoing lumbar surgery: a randomized trial comparing propofol-remifentanil total i.v. anesthesia with sevoflurane anesthesia

Background

Previous studies have shown that women achieve a better quality of postoperative recovery from total intravenous anesthesia (TIVA) than from inhalation anesthesia, but the effect of anesthesia type on recovery in male patients is unclear. This study therefore compared patient recovery between males undergoing lumbar surgery who received TIVA and those who received sevoflurane anesthesia.

Methods

Eighty male patients undergoing elective one- or two-level primary transforaminal lumbar interbody fusion (TLIF) were randomly divided into two groups: the TIVA group (maintenance was achieved with propofol and remifentanil) or sevoflurane group (SEVO group: maintenance was achieved with sevoflurane and remifentanil). The quality of recovery-40 questionnaire (QoR-40) was administered before surgery and on postoperative days 1 and 2 (POD1 and POD2). Pain scores, postoperative nausea and vomiting, postoperative hospital stay, anesthesia consumption, and adverse effects were recorded.

Results

The QoR-40 scores were similar on the three points (Preoperative, POD1 and POD2). Pain scores were significantly lower in the SEVO group than in the TIVA group on POD1 (30.6 vs 31.4; P = 0.01) and POD2 (32 vs 33; P = 0.002). There was no significant difference in the postoperative hospital stay or complications in the postanesthesia care unit between the TIVA group and the SEVO group.

Conclusions

This study demonstrates that the quality of recovery is not significantly different between male TLIF surgery patients who receive TIVA and those who receive sevoflurane anesthesia. Patients in the TIVA group had better postoperative analgesic effect on POD2.

Trial registration

This was registered at http://www.chictr.org.cn (registration number ChiCTR-IOR-16007987, registration date: 24/02/2016).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01519-y.

Mammalian Transient Receptor Potential TRPA1 Channels: From Structure to Disease

The transient receptor potential ankyrin (TRPA) channels are Ca²⁺-permeable nonselective cation channels remarkably conserved through the animal kingdom. Mammals have only one member, TRPA1, which is widely expressed in sensory neurons and in non-neuronal cells (such as epithelial cells and hair cells). TRPA1 owes its name to the presence of 14 ankyrin repeats located in the NH₂ terminus of the channel, an unusual structural feature that may be relevant to its interactions with intracellular components. TRPA1 is primarily involved in the detection of an extremely wide variety of exogenous stimuli that may produce cellular damage. This includes a plethora of electrophilic compounds that interact with nucleophilic amino acid residues in the channel and many other chemically unrelated compounds whose only common feature seems to be their ability to partition in the plasma membrane. TRPA1 has been reported to be activated by cold, heat, and mechanical stimuli, and its function is modulated by multiple factors, including Ca²⁺, trace metals, pH, and reactive oxygen, nitrogen, and carbonyl species. TRPA1 is involved in acute and chronic pain as well as inflammation, plays key roles in the pathophysiology of nearly all organ systems, and is an attractive target for the treatment of related diseases. Here we review the current knowledge about the mammalian TRPA1 channel, linking its unique structure, widely tuned sensory properties, and complex regulation to its roles in multiple pathophysiological conditions.

Anesthetic Efficacy of Dexmedetomidine versus Midazolam When Combined with Remifentanil for Percutaneous Transluminal Angioplasty in Patients with Peripheral Artery Disease

Anesthesia for percutaneous transluminal angioplasty (PTA) involves a high-risk population having a broad spectrum of pain character and intensity. This study delved the anesthetic efficacy of dexmedetomidine versus midazolam, when used with remifentanil. Seventy patients scheduled for femoropopliteal PTA were randomized into two groups receiving either intermittent midazolam boluses (0.03–0.05 mg/kg) (MR group) or dexmedetomidine 0.2–0.7 μg/kg/h after a loading dose of 1.0 μg/kg for 10 min (DR group), both with remifentanil. The primary endpoint was the patients’ satisfaction (1–5, 5; extremely satisfied). Secondary endpoints included postprocedural pain scores (0–10, 10; worst imaginable pain) and adverse events. The satisfaction level of patients was significantly greater in the DR group compared with the MR group (4.0 [3.0, 5.0] versus 4.0 [2.0, 5.0] p = 0.021). The number of patients having a postprocedural pain score of at least 3 was significantly greater in the MR group compared with the DR group (10 [29%] versus 2 [6%], p = 0.013). The number of patients with hypotensive episodes was higher in the DR group (5 [14.7%] versus 0, p = 0.025), which could all be restored with ephedrine. The use of dexmedetomidine in conjunction with remifentanil may be a safe option that provides excellent patient satisfaction while potentially attenuating postprocedural pain.

Propofol attenuates postoperative hyperalgesia via regulating spinal GluN2B-p38MAPK/EPAC1 pathway in an animal model of postoperative pain

BACKGROUND

Total intravenous anesthesia with propofol has been shown to reduce postoperative pain in some clinical studies, but knowledge of its underlying analgesic mechanism remains limited. In this study, we compared the analgesic effects of propofol versus isoflurane in an animal model of postoperative pain and evaluated its underlying molecular mechanisms.

METHODS

Plantar incision was made in the hind paws of rats under general anesthesia with 2.5% of inhalational isoflurane (isoflurane group) or intravenous infusion of propofol (1.5 mg kg^-1  min^-1 , propofol group). Mechanical allodynia was assessed by paw withdrawal threshold before and after incision. Spinal dorsal horns (L3-L5) were harvested 1 hr after incision to assess the level of phosphorylated GluN2B, p38MAPK, ERK, JNK, and EPAC using Western blot and immunofluorescence.

RESULTS

Mechanical allodynia induced by plantar incision peaked at 1 hr and lasted for 3 days after incision. It was significantly less in the propofol group compared with the isoflurane group in the first 2 hr following incision. The incision-induced increases in phosphorylated GluN2B, p38MAPK, and EPAC1 were significantly reduced in the propofol group. The number of spinal dorsal neurons co-expressed with EPAC1 and c-Fos after the incision was significantly lower in the propofol group.

CONCLUSION

Propofol reduced pain responses in an animal model of postoperative pain and suppressed the spinal GluN2B-p38MAPK/EPAC1 signaling pathway. Since the p38MAPK/EPAC pathway plays a critical role in the development of postoperative hyperalgesia, our results provide evidence-based behavioral, molecular, and cellular mechanisms for the analgesic effects of propofol when used for general anesthesia.

SIGNIFICANCE

These findings may provide a new mechanism for the postsurgical analgesic effect of propofol, which is particularly interesting during the subacute period after surgery as it is the critical period for the development of persistent postsurgical pain.

Inhibition by general anesthetic propofol of compound action potentials in the frog sciatic nerve and its chemical structure

Although the intravenous general anesthetic propofol (2,6-diisopropylphenol) has an ability to inhibit nerve conduction, this has not been fully examined. Various agents inhibit compound action potentials (CAPs) in a manner dependent on their chemical structures. To determine propofol's chemical structure that is important in nerve conduction inhibition, we examined the effects of propofol and its related compounds on fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Propofol concentration-dependently reduced the peak amplitude of the CAP with a half-maximal inhibitory concentration (IC₅₀) value of 0.14 mM. A similar inhibition was produced by other phenols, 4-sec-butylphenol and 4-amylphenol (IC₅₀ values: 0.33 and 0.20 mM, respectively). IC₅₀ values for these and more phenols (4-isopropylphenol, 4-tert-butylphenol, and 4-ter-amylphenol; data published previously) were correlated with the logarithm of their octanol-water partition coefficients. A phenol having ketone group (raspberry ketone) and alcohols (3-phenyl-1-propanol and 2-phenylethylalcohol) inhibited CAPs less effectively than the above-mentioned phenols. The local anesthetic (LA) benzocaine reduced CAP peak amplitudes with an IC₅₀ of 0.80 mM, a value larger than that of propofol. When compared with other LAs, propofol activity was close to those of ropivacaine, levobupivacaine, and pramoxine, while benzocaine activity was similar to those of cocaine and lidocaine. It is concluded that propofol inhibits nerve conduction, possibly owing to isopropyl and hydroxyl groups bound to the benzene ring of propofol and to its lipophilicity; propofol's efficacy is comparable to those of some LAs. These results could serve to develop propofol-related agents exhibiting analgesia when applied topically.

Propofol vs. inhalational agents to maintain general anaesthesia in ambulatory and in-patient surgery: a systematic review and meta-analysis

Background

It is unclear if anaesthesia maintenance with propofol is advantageous or beneficial over inhalational agents. This study is intended to compare the effects of propofol vs. inhalational agents in maintaining general anaesthesia on patient-relevant outcomes and patient satisfaction.

Methods

Studies were identified by electronic database searches in PubMed™, EMBASE™ and the Cochrane™ library between 01/01/1985 and 01/08/2016. Randomized controlled trials (RCTs) of peer-reviewed journals were studied. Of 6688 studies identified, 229 RCTs were included with a total of 20,991 patients. Quality control, assessment of risk of bias, meta-bias, meta-regression and certainty in evidence were performed according to Cochrane. Common estimates were derived from fixed or random-effects models depending on the presence of heterogeneity. Post-operative nausea and vomiting (PONV) was the primary outcome. Post-operative pain, emergence agitation, time to recovery, hospital length of stay, post-anaesthetic shivering and haemodynamic instability were considered key secondary outcomes.

Results

The risk for PONV was lower with propofol than with inhalational agents (relative risk (RR) 0.61 [0.53, 0.69], p < 0.00001). Additionally, pain score after extubation and time in the post-operative anaesthesia care unit (PACU) were reduced with propofol (mean difference (MD) − 0.51 [− 0.81, − 0.20], p = 0.001; MD − 2.91 min [− 5.47, − 0.35], p = 0.03). In turn, time to respiratory recovery and tracheal extubation were longer with propofol than with inhalational agents (MD 0.82 min [0.20, 1.45], p = 0.01; MD 0.70 min [0.03, 1.38], p = 0.04, respectively). Notably, patient satisfaction, as reported by the number of satisfied patients and scores, was higher with propofol (RR 1.06 [1.01, 1.10], p = 0.02; MD 0.13 [0.00, 0.26], p = 0.05). Secondary analyses supported the primary results.

Conclusions

Based on the present meta-analysis there are several advantages of anaesthesia maintenance with propofol over inhalational agents. While these benefits result in an increased patient satisfaction, the clinical and economic relevance of these findings still need to be addressed in adequately powered prospective clinical trials.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0632-3) contains supplementary material, which is available to authorized users.

Propofol produces preventive analgesia via GluN2B-containing NMDA Receptor/ERK1/2 Signaling Pathway in a rat model of inflammatory pain

Abstract

Propofol, an intravenous anesthetic, has been shown to offer superior analgesic effect clinically. Whether propofol has preventive analgesic property remains unexplored. The present study investigated the antinociceptive effect of propofol and underlying molecular and cellular mechanisms via pre-emptive administration in a formalin-induced inflammatory pain model in rats. Male adult Sprague–Dawley rats were randomly allocated into four groups: naïve (Group Naïve), formalin injection only (Group Formalin), and formalin injection at 30 min (Group P-30 min) or 2 h (Group P-2 h) after intravenous infusion of propofol (0.6 mg kg−1 min−1) for 1 h. Nociceptive responses and protein expression of phosphorylated- or pan-GluN2B, ERK1/2, p38 mitogen-activated protein kinase, and c-Jun N-terminal kinase in the spinal dorsal horn were evaluated. Alteration of intracellular Ca2+ concentration induced by N-methyl-D-aspartate (NMDA) receptor agonists with or without pre-treatment of propofol was measured using fluorometry in SH-SY5Y cells while neuronal activation in the spinal dorsal horn by immunofluorescence. Pre-emptive propofol reduced pain with a delayed response to formalin and a reduction in hypersensitivity that lasted at least for 2 h. The formalin-induced activation of spinal GluN2B and ERK1/2 but not p38 or c-Jun N-terminal kinase was also diminished by propofol treatment. Preconditioning treatment with 3 µM and 10 µM of propofol inhibited Ca2+ influx mediated through NMDA receptors in SH-SY5Y cells. Propofol also reduced the neuronal expression of c-Fos and p-ERK induced by formalin. This study shows that pre-emptive administration of propofol produces preventive analgesic effects on inflammatory pain through regulating neuronal GluN2B-containing NMDA receptor and ERK1/2 pathway in the spinal dorsal horn.

Propofol inhibits expression of angiotensin II receptor type 2 in dorsal root ganglion neurons

The renin-angiotensin system (RAS) is involved in nociception and has functions in the cardiovascular system. The primary role of the RAS is to mediate the effect of angiotensin II (Ang II) through Ang II receptor type 2 (AT2). Due to this, AT2 has become a novel therapeutic target for the relief of peripheral neuropathic pain in humans. As it is one of the most popular induction agents of general anesthesia, propofol also exerts peripheral antinociceptive effects. The present study assessed the effect of propofol on the expression of AT2 in cultured dorsal root ganglion (DRG) neurons. The results indicate that propofol decreases AT2 mRNA expression in a statistically significant dose- and time-dependent manner (P<0.05). This resulted in a marked decrease in AT2 protein expression and the density of Ang II-binding AT2 on the cell membrane of DRG neurons. The effect of propofol was reversed by LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor. Although propofol exhibited no significant effect on AT2 gene promoter activity, it significantly decreased the stability of AT2 mRNA (P<0.05). However, this effect was reversed by LY294002. In addition, propofol increased PI3K activity in a concentration-dependent manner in DRG neurons. In conclusion, to the best of our knowledge, the current study provides the first evidence suggesting that propofol inhibits the expression of AT2 in DRG neurons by decreasing the stability of AT2 mRNA through a PI3K-dependent mechanism. The present study provides novel insights into the mechanisms of the peripheral antinociceptive action of propofol and suggests a potential means of regulating Ang II/AT2 signaling in the peripheral nervous system.

Subhypnotic doses of propofol impair spatial memory retrieval in rats

Abundant evidence indicates that propofol profoundly affects memory processes, although its specific effects on memory retrieval have not been clarified. A recent study has indicated that hippocampal glycogen synthase kinase-3β (GSK-3β) activity affects memory. Constitutively active GSK-3β is required for memory retrieval, and propofol has been shown to inhibit GSK-3β. Thus, the present study examined whether propofol affects memory retrieval, and, if so, whether that effect is mediated through altered GSK-3β activity. Adult Sprague-Dawley rats were trained on a Morris water maze task (eight acquisition trials in one session) and subjected under the influence of a subhypnotic dose of propofol to a 24-hour probe trial memory retrieval test. The results showed that rats receiving pretest propofol (25 mg/kg) spent significantly less time in the target quadrant but showed no change in locomotor activity compared with those in the control group. Memory retrieval was accompanied by reduced phosphorylation of the serine-9 residue of GSK-3β in the hippocampus, whereas phosphorylation of the tyrosine-216 residue was unaffected. However, propofol blocked this retrieval-associated serine-9 phosphorylation. These findings suggest that subhypnotic propofol administration impairs memory retrieval and that the amnestic effects of propofol may be mediated by attenuated GSK-3β signaling in the hippocampus.

Effect of GABA on blood pressure and blood dynamics of anesthetic rats

BACKGROUND

This study aimed to investigate GABA effects on blood pressure and blood dynamics of anesthetic rats by observing spontaneously hypertensive rats under both anesthesia and waking state.

MATERIALS AND METHODS

72 male waking Wistar-Kyokos (WKY) rats and 72 male anesthetized spontaneously hypertensive (SHR) rats were randomly divided into control group and experimental group (N = 36 each). Rats were further divided into three subgroups (N = 12 each), which received 15 μmol GABA, 35 nmol muscimol, or 4 nmol dicentrine into unilateral paraventricular nucleus, respectively. Rats in the control group (WKY1) and experimental group (SHR1) were compared for the GABA effect on blood pressure (MAP), heart rate (HR), and arterial baroreceptor reflex function (BRS) changes under waking state. Anesthetic WKY rats (WKY2) and spontaneously hypertensive rats (SHR2) were compared for the GABA effect on those abovementioned indexes. Abdominal aorta mean arterial pressure, heart rate, and arterial baroreceptor reflex function changes were compared in all rats.

RESULTS

MAP, HR, and BRS were slightly lower in the rats under anesthetic state than in waking state before treatment (P < 0.05); they did not show significant changes between anesthetic and waking state, however, after treatment (P > 0.05). Unilateral paraventricular nucleus injection of GABA or muscimol elevated MAP, HR, and BRS in both normal and spontaneously hypertensive rats under waking or anesthetic state (P < 0.05). In addition, the amplitudes of changes of three indicators in spontaneously hypertensive group were markedly higher than those of control group (P < 0.05). Dicentrine could induce MAP and HR to increase, while BRS decreased significantly (P < 0.05). The amplitudes of changes in spontaneously hypertensive group were larger than those of normal group (P < 0.05).

CONCLUSION

Centrally GABA injection can enhance the BRS function in spontaneously hypertensive rats and adjust heart rate to reduce the blood pressure fluctuation. It may play a role in reducing blood pressure and protecting cardiovascular function.

Propofol differentially inhibits the release of glutamate, γ-aminobutyric acid and glycine in the spinal dorsal horn of rats

OBJECTIVES

Propofol (2, 6-diisopropylphenol) is an intravenous anesthetic that is commonly used for the general anesthesia. It is well known that the spinal cord is one of the working targets of general anesthesia including propofol. However, there is a lack of investigation of the effects of propofol on spinal dorsal horn which is important for the sensory transmission of nociceptive signals. The objective of this study was to investigate the effects of increasing dosage of propofol on the release of glutamate (Glu), γ-aminobutyric acid (GABA) and glycine (Gly) in the spinal dorsal horn.

MATERIALS AND METHODS

The efflux of Glu, GABA or Gly in the spinal dorsal horn of rats was detected using transverse spinal microdialysis under an awake condition and various depths of propofol anesthesia. The infusion rates of propofol were, in order, 400 µg/(kg·min), 600 µg/(kg·min) and 800 µg/(kg·min), with a 20 min infusion period being maintained at each infusion rate.

RESULTS

Propofol decreased the glutamate efflux within spinal dorsal horn in a dose-dependent manner, and the maximum decrease was 56.8 ± 6.0% at high-dose propofol infusion producing immobility. The inhibitory GABA and Gly efflux was also decreased about 15-20% at low-dose propofol infusion only producing sedation, but did not continue to drop with higher doses of propofol.

CONCLUSION

Propofol decreased both excitatory and inhibitory amino acids efflux in spinal dorsal horn, and the preferential suppression of the excitatory amino acid might be associated with the analgesic effect of propofol.

Thermosensitive transient receptor potential (TRP) channel agonists and their role in mechanical, thermal and nociceptive sensations as assessed using animal models

INTRODUCTION

The present paper summarizes research using animal models to investigate the roles of thermosensitive transient receptor potential (TRP) channels in somatosensory functions including touch, temperature and pain. We present new data assessing the effects of eugenol and carvacrol, agonists of the warmth-sensitive TRPV3, on thermal, mechanical and pain sensitivity in rats.

METHODS

Thermal sensitivity was assessed using a thermal preference test, which measured the amount of time the animal occupied one of two adjacent thermoelectric plates set at different temperatures. Pain sensitivity was assessed as an increase in latency of hindpaw withdrawal away from a noxious thermal stimulus directed to the plantar hindpaw (Hargreaves test). Mechanical sensitivity was assessed by measuring the force exerted by an electronic von Frey filament pressed against the plantar surface that elicited withdrawal.

RESULTS

Topical application of eugenol and carvacrol did not significantly affect thermal preference, although there was a trend toward avoidance of the hotter surface in a 30 vs. 45°C preference test for rats treated with 1 or 10% eugenol and carvacrol. Both eugenol and carvacrol induced a concentration-dependent increase in thermal withdrawal latency (analgesia), with no significant effect on mechanosensitivity.

CONCLUSIONS

The analgesic effect of eugenol and carvacrol is consistent with previous studies. The tendency for these chemicals to increase the avoidance of warmer temperatures suggests a possible role for TRPV3 in warmth detection, also consistent with previous studies. Additional roles of other thermosensitive TRP channels (TRPM8 TRPV1, TRPV2, TRPV4, TRPM3, TRPM8, TRPA1, TRPC5) in touch, temperature and pain are reviewed.