This study aims to evaluate tramadol’s effect during elective ovariectomy in female dogs under general anesthesia with isoflurane, premedicated with 0.025 mg/kg medetomidine IM, 0.2 mg/kg methadone IM and 2 mg/kg ketamine IM. Seventeen female dogs were divided into control (CG) and tramadol (TG) groups. Dogs in the TG also received a 4 mg/kg IV tramadol bolus one minute prior to skin incision. Heart rate (HR), systolic blood pressure, and mean blood pressure were recorded at baseline, skin incision, traction (T1) and clamping (T2) of the right ovarian pedicle, and traction and clamping of the left ovarian pedicle. Tramadol caused a 39.8% (p<0.05) and a 31.9% (p<0.05) HR increase at T1 and T2, respectively, when compared to the CG, which lasted a maximum of eight minutes. Although tramadol has a potential positive chronotropic effect, it can safely provide additional intraoperative analgesia before intense noxious stimuli, for at least seven minutes.

Background: The isoflurane minimum alveolar concentration (MAC) was measured in rats chronically treated with WIN 55,212-2. Methods: The isoflurane MAC was determined in 24 male rats from the end expiratory samples at time of tail clamping under the following conditions: without treatment (MACISO), in rats treated for 21 days with WIN 55,212-2 (MACISO+WIN55) and other group 8 days after stopping treatment for 21 days with WIN 55,212-2 (MACISO+WIN55+8D). Results: The MACISO was 1.32 ± 0.06. In the MACISO+WIN55 group the MAC increase to 1.69 ± 0.09 (28%). After 8 days stopping treatment, MAC did not decrease significantly 1.67 ± 0.07 (26%). Conclusions: The administration for 21 days of WIN 55,212-2 increases the MAC of isoflurane in rats; this effect does not disappear after 8 days of discontinuing treatment with the synthetic cannabinoid.

The therapeutic effects of volatile anesthetics on mental diseases, particularly schizophrenia, have gained considerable interest. Although isoflurane is a commonly used volatile anesthetic, there’s no more evidence that it could work on treating schizophrenia. Here, we discovered that inhaling isoflurane at low concentrations might reverse the behavioral phenotypes of schizophrenia caused by MK801, such as hyperlocomotion, pre-pulse inhibition impairment, and working memory loss. Isoflurane also helped recovering adult neurogenesis and synaptic plasticity impairments in the dentate gyrus (DG) induced by MK801. To better understand the mechanism, we discovered that isoflurane could reverse the reduction of parvalbumin (PV)-positive GABAergic interneuron (PVI) number and the aberration of NRG1-ErbB4 signaling in the DG; however, isoflurane could not reverse the schizophrenia-related phenotypes caused by PVI ablation, indicating that PVI are necessary for the therapeutic effect of isoflurane. Interestingly, isoflurane could reverse phenotypes caused by blocking PVIs GABA release in the DG, indicating the therapeutic impact is independent of PVI GABA release. Our research revealed that isoflurane might be used to treat schizophrenia, possibly through PVI in the DG.

A wide variety of substances have been used to anaesthetise invertebrates, but many are not anaesthetics and merely incapacitate animals, rather than preventing pain. Much is now known about the mode of action of modern clinical and veterinary anaesthetics because of their use on human beings and other vertebrates. In essence, the role of an ideal general anaesthetic is to act as a muscle relaxant, an analgesic, an anaesthetic and an amnesic. To achieve all these properties with a single substance is difficult and various adjuvants usually need to be administered, resulting in a cocktail of drugs. In a clinical setting, the vast majority of patients are unaware of surgery being carried out and have no memory of it, so they can claim to have felt no pain, but this is much more difficult to demonstrate in invertebrates. Here we show that 1% MgCl2, a muscle relaxant, is a useful adjuvant for the clinical anaesthetic isoflurane on Octopus vulgaris when applied for 10 minutes before the clinical anaesthetic. After this, full anaesthesia can be achieved in 5 minutes using only 1% isoflurane and from which full recovery takes place rapidly in about 10 to 15 minutes. This reduces stress on the animal and minimises the quantity of anaesthetic used.

We tested the hypothesis that obesity influences the pharmacodynamics of volatile general anesthetics (VGAs) by comparing effects of anesthetic exposure on mortality from traumatic brain injury (TBI) in lean and obese Drosophila melanogaster. We induced TBI with a High-Impact Trauma device. Starvation-selection over multiple generations resulted in an obese phenotype (SS flies). Fed flies served as lean controls (FC flies). Adult (1-7 day old) SS and FC flies were exposed to equianesthetic doses of isoflurane or sevoflurane either before or after TBI. The principal outcome was percent mortality 24 hours after injury, expressed as the Mortality Index at 24 hours (MI24). TBI resulted in lower MI24 in FC than in SS flies (21 (2.35) and 57.8 (2.14), respectively n= 12, p=0.0001). Preexposure to isoflurane or sevoflurane preconditioned FC flies to TBI reducing the risk of death to 0.53 [0.25 to 1.13] and 0.82 [0.43 to 1.58], respectively, but had no preconditioning effect in SS flies. Postexposure to isoflurane or sevoflurane increased the risk of death in SS flies. Only postexposure to isoflurane increased the risk in FC flies (1.39 [0.81 to 2.38]). Thus, obesity affects the pharmacodynamics of VGAs, thwarting the preconditioning effect of isoflurane and sevoflurane in TBI.

The effects of morphine (MOR) and dexmedetomidine (DEX) on the MAC of isoflurane were measured in rats chronically treated with the synthetic cannabinoid WIN 55,212-2 (WIN55). Methods: The MAC of isoflurane was determined in 32 male rats from expiratory samples at the time of tail clamping. The effects of morphine (MAC(ISO+MOR)) and dexmedetomidine (MAC(ISO+DEX)) on the MAC of isoflurane in untreated rats and rats treated for 21 days with WIN 55,212-2 (MAC(ISO+WIN55+MOR)) and (MAC(ISO+WIN55+DEX)) were measured. Prior to the administration of morphine and dexmedetomidine, the MAC of the isoflurane was measured in both untreated rats (MAC(ISO)) and those treated with WIN 55,212-2 (MAC(ISO+WIN55)). Results: The minimum alveolar concentration was measured as 1.32 ± 0.06 in the MAC(ISO) group and 1.69 ± 0.09 in the MAC(ISO+WIN55) group. The MAC of the MAC(ISO+MOR) group was 0.97 ± 0.02 (26% less than the control group, MAC(ISO)). MAC was measured as 1.55 ± 0.08 in the MAC(ISO+WIN55+MOR) group (8% less than the MAC(ISO+WIN55) group), 0.68 ± 0.10 in the MAC(ISO+DEX) group (48% less than the control group, MAC(ISO)), and 0.67 ± 0.08 in the MAC(ISO+WIN55+DEX) group (60% less than the MAC(ISO+WIN55) group). Conclusions: The administration of WIN 55,212-2 for 21 days increases the MAC of isoflurane in rats. The sparing effect on isoflurane of morphine decreases in rats chronically treated with the synthetic cannabinoid, WIN 55,212-2. Dexmedetomidine increases its sparing effect on the minimum alveolar concentration of isoflurane in rats chronically treated with WIN 55,212-2.