The question whether decapitation is a humane method of euthanasia in awake animals is being debated. To gather arguments in this debate, obsolete rats were decapitated while recording the EEG, both of awake rats and of anesthetized rats. Following decapitation a fast and global loss of power of the EEG was observed; the power in the 13-100 Hz frequency band, expressing cognitive activity, decreased according to an exponential decay function to half the initial value within 4 seconds. Whereas the pre-decapitation EEG of the anesthetized animals showed a burst suppression pattern quite different from the awake animals, the power in the postdecapitation EEG did not differ between the two groups. This might indicate that either the power of the EEG does not correlate well with consciousness or that consciousness is briefly regained in the anesthetized group after decapitation. Remarkably, after 50 seconds (awake group) or 80 seconds (anesthetized group) following decapitation, a high amplitude slow wave was observed. The EEG before this wave had more power than the signal after the wave. This wave might be due to a simultaneous massive loss of membrane potentials of the neurons. Still functioning ion channels, which keep the membrane potential intact before the wave, might explain the observed power difference. Two conclusions were drawn from this experiment. It is likely that consciousness vanishes within seconds after decapitation, implying that decapitation is a quick and not an inhumane method of euthanasia. It seems that the massive wave which can be recorded approximately one minute after decapitation reflects the ultimate border between life and death. This observation might have implications in the discussions on the appropriate time for organ donation.
... However, there remains very little scientific evidence showing that cervical dislocation produces a reliable and/or a humane death. 53 Assumptions that cervical dislocation offers a humane death arise from data extrapolated from the decapitation of rats, [54][55][56][57][58] and data surrounding the specific welfare impacts of cervical dislocation remain sparse in rodents. 53,59 This is particularly concerning given that cervical dislocation is very different from decapitation, with a different mode of action, and of course mice are not small rats. ...
... However, this claim remains highly controversial and unsubstantiated, and the assertion that such high frequency signals reflect pain and discomfort has been heavily criticised. 54,56,58 One strong counterargument comes from findings showing that high frequency EEG signals are also present whilst under general anaesthesia, 33,69,70 as well as during rapid eye movement (REM) sleep. 27 Moreover, it has also been argued that, following decapitation, rapid blood loss would result in hypoxia rendering the decapitated head unconscious in less than 2.7 s, 55 and that lack of blood supply would be unable to support ongoing brain activity. ...
... 27 Moreover, it has also been argued that, following decapitation, rapid blood loss would result in hypoxia rendering the decapitated head unconscious in less than 2.7 s, 55 and that lack of blood supply would be unable to support ongoing brain activity. 64 In subsequent EEG work, it took 17 s following decapitation for the EEG signal to become isoelectric, with the power of the frequency bands expressing cognitive activity (13-100 Hz) decreasing exponentially to less than 50% of baseline power, representative of an unconscious state, after 3.7 s. 58 This result was corroborated in 1992 by loss of consciousness reported in 3-6 s, 56 as well as disputed by a later study demonstrating that brain activity (EEG and VEP assessment) was sustained for relatively long periods following decapitation (15-20 s). 59 EEG and VEP assessment are useful indicators but have limitations to their use. ...
Rodents are the most widely used species for scientific purposes. A critical pre-requisite of their use, based on utilitarian ethical reasoning, is the provision of a humane death when necessary for scientific or welfare grounds. Focussing on the welfare challenges presented by current methods, we critically evaluate the literature, consider emerging methodologies that may have potential for refinement and highlight knowledge gaps for future research. The evidence supports the conclusion that scientists and laboratory personnel should seek to avoid killing laboratory rodents by exposing them to carbon dioxide (CO 2 ), unless exploiting its high-throughput advantage. We suggest that stakeholders and policymakers should advocate for the removal of CO 2 from existing guidelines, instead making its use conditionally acceptable with justification for additional rationale for its application. With regards to physical methods such as cervical dislocation, decapitation and concussion, major welfare concerns are based on potential inaccuracy in application and their susceptibility to high failure rates. There is a need for independent quality-controlled training programmes to facilitate optimal success rates and the development of specialist tools to improve outcomes and reliability. Furthermore, we highlight questions surrounding the inconsistent inclusion criteria and acceptability of physical methods in international regulation and/or guidance, demonstrating a lack of cohesion across countries and lack of a comprehensive ‘gold standard’ methodology. We encourage better review of new data and championing of open access scientific resources to advocate for best practice and enable significant changes to policy and legislation to improve the welfare of laboratory rodents at killing.
... Thus, the maximum time that pain and distress may be perceived is 2.7 seconds [13]. Since then, this approximate measurement -sometimes increased to three to six seconds -remains the rule of thumb for estimating the time to LOC in decapitated rodents [14,15]. Most tellingly, in the 2000 Report of the AVMA Panel on Euthanasia, the Panel dismissed its earlier concern over decapitation and ruled that it was a humane method of euthanasia for rodent models [12]. ...
Since the development of the infamous guillotine in the French Revolution, physicians have debated how long consciousness persists in decapitated heads. Fueled by anecdotes of severed heads that blink, blush, and appear to retain intelligence, numerous experiments have investigated this macabre subject for nearly 250 years. In this paper, we examine the evidence, both historical and modern, and ultimately conclude that, while the truth may never be fully known, all evidence appears to indicate that loss of consciousness appears to occur within seconds of decapitation. The rumors that circulated through the European consciousness during the Terror of the French Revolution appear to be just that - curious urban legends from an awed and terrified public.
... On 10th day of experiment, rats were deeply anaesthetized by 30% chloroform. Painless death of the deeply anesthetized rats were ensured by decapitation 31 . Five (5) ml of blood samples were collected by cardiac puncture of each rat. ...
Background: In Ayurveda turmeric (Curcuma longa) has been used for cardioprotection. Experimentally induced myocardial injury is clinically similar to human myocardial infarction. Objective: The study was designed to assess the myocardial salvagingeffect of turmeric (Curcuma longa) on experimentally induced myocardial injury in rats. Methods: This experimental study was carried out in the Department of Physiology, Dhaka Medical College, Dhaka during 2015. Total twenty eight (28) Wistar albino male rats (aged 13±1 weeks; 125±25 gm) were randomly grouped into NS (normal control group), ISO (isoproterenol treated control group),Tm+ISO (turmeric pretreated and isoproterenol treated group) and Am+ISO (amlodipine pretreated and isoproterenol treated group). All the rats were sacrificed on 10th day of experimentation. . Blood samples were collected. Serum carduac troponin I (cTnI) level was estimated by AxSYM methodand serum malondialdehyde (MDA) level was estimated byspectrophotometric method.For statistical analysis, one way ANOVA followed by Bonferroni post hoc test was done by using SPSS 22.0 version. Results: The mean serum cTnI and MDA level was significantly (P<0.001) higher in ISO in comparison to all other rats of different groups. Whereas, the mean serum cTnI level was lower in Tm+ISO and Am+ISO in comparison to that of ISO which were statistically significant (P<0.05). Again, mean serum MDA level was significantly lower in Tm+ISO(P<0.05) and Am+ISO(P<0.001) in comparison to that of ISO.However, there were no significant differences between Tm+ISO and Am+ISO. Conclusion: The results of the study concluded that turmeric has myocardial salvaging effect on experimentally induced myocardial injury inrats. J Bangladesh Soc Physiol. 2022, June; 17(1): 34-40
... Although I do appreciate Greyson's (2021b) cautioning any premature over-estimation of the potential explanatory power of psychedelic neurotransmission near-death, or indeed an otherwise more complex neural model congruent with psychedelic action-as indicated above, it is still important to accentuate that if endogenous psychedelics were in fact implicated in human NDEs, the emerging data as to the release of DMT and a host of other neurotransmitters during the death of animal models (Dean et al., 2019;Li et al., 2015) is precisely the data one would expect. Crucially, this is equally the case for the litany of evidence for distinct, often sophisticated neuroelectric activity upon not only rodent death (Borjigin et al., 2013;Lee et al., 2017;van Rijn et al., 2011;Zhang et al., 2019) but also human death (Auyong et al., 2010;Chawla et al., 2009Chawla et al., , 2017Dreier et al., 2018;Norton et al., 2017). ...
The present article constitutes a final rejoinder to the response Bruce Greyson made to my commentary provided on his recent book After. It follows a linear flow, addressing Greyson's statements to my commentary sequentially , ultimately concluding that although we agree on many points, several discrepancies between our arguments remain. In short, these pivot around my perspective that, firstly, the intricacies of the latest developments in the neu-rosciences are indispensably illuminative of the potential mechanisms of near-death experiences (NDEs)-which entails either endogenous psychedelic transmission or neural activity synonymous with psychedelic effects. And secondly, such a neural embrace need not be immiscible with non-local consciousness, with such non-locality being implied by the 'super-psi' hypothesis, which may explain many otherwise inexplicable dimensions of NDEs-whereby, again, psy-chedelic effects may, non-reductively, be implicated. The evidence for survival, however, is less certain-but the probability is raised in light of this.
... Although I do appreciate Greyson's (2021b) cautioning any premature over-estimation of the potential explanatory power of psychedelic neurotransmission near-death, or indeed an otherwise more complex neural model congruent with psychedelic action-as indicated above, it is still important to accentuate that if endogenous psychedelics were in fact implicated in human NDEs, the emerging data as to the release of DMT and a host of other neurotransmitters during the death of animal models (Dean et al., 2019;Li et al., 2015) is precisely the data one would expect. Crucially, this is equally the case for the litany of evidence for distinct, often sophisticated neuroelectric activity upon not only rodent death (Borjigin et al., 2013;Lee et al., 2017;van Rijn et al., 2011;Zhang et al., 2019) but also human death (Auyong et al., 2010;Chawla et al., 2009Chawla et al., , 2017Dreier et al., 2018;Norton et al., 2017). ...
... This concept has not been studied in depth, although there is data on the effect of electromagnetic radiation immediately after fertilization on further fetal development in mice [37]. Additionally, there is evidence that during death, rats exhibit increased electrical activity (a 'death wave') [38], which theoretically can affect the body in the vicinity of the dying subject. ...
The aim of this work was to study whether epigenetic events at conception influence the formation of behavioral features found in adult rats. First generational inheritance of activity level, anxiety like behavior, and learning ability was studied. To separate genetic and non-genetic inheritance, mating of males and females with average motor activity was carried out in the presence anesthetized or conscious males with high or low activity. Our results show that offspring of parents who mated in the presence of males with a high motor activity were significantly more active than offspring of parents that were paired in the presence of males with low activity. Anxiety like behavior and learning ability were not inherited in this way. It is possible that the phenomenon we discovered is important for maintaining a certain level of activity of specific populations of animals. It counteracts natural selection, which should lead to a constant increase in the activity of animals.
... Euthanasia. Rats were euthanized by rapid decapitation (Holson, 1992;van Rijn et al., 2011). ...
Epilepsy is a disabling, chronic brain disease,affecting ~1% of the World’s population, characterized by recurrent seizures (sudden, uncontrolled brain activity), which may manifest with motor symptoms (e.g., convulsions) or non-motor symptoms. Temporal lobe epilepsies (TLE) compromising the hippocampus are the most common form of focal epilepsies. Resistance in ~1/3 of epileptic patients to the first line of treatment, i.e., antiepileptic drugs (AEDs), has been an important motivation to seek alternative treatments. Among these, the plant Cannabis sativa (commonly known as marihuana) or compounds extracted from it (cannabinoids) have gained widespread popularity. Moreover, sex differences have been proposed in epilepsy syndromes and in cannabinoid action. In the hippocampus, cannabinoids interact with the CB1R receptor whose membrane levels are regulated by β-Arrestin2, a protein that promotes its endocytosis and causes its downregulation. In this article, we evaluate the modulatory role of WIN 55,212-2 (WIN), a synthetic exogenous cannabinoid on behavioral convulsions and on the levels of CB1R and β-Arrestin2 in female and male adolescent rats after a single injection of the proconvulsant pentylenetetrazol (PTZ). As epilepsies can have a considerable impact on synaptic proteins that regulate neuronal toxicity, plasticity, and cognition, we also measured the levels of key proteins markers of excitatory synapses, in order to examine whether exogenous cannabinoids may prevent such pathologic changes after acute seizures. We found that the exogenous administration of WIN prevented convulsions of medium severity in females and males and increased the levels of phosphorylated CaMKII in the hippocampus. Furthermore, we observed a higher degree of colocalization between CB1R and β-Arrestin2 in the granule cell layer.
... All groups were treated for 2 months. On the 60 th day, blood samples were taken from the retroorbital plexus under light anesthesia according to Van Rijn et al. (22). ...
Objective(s): The testis is the male reproductive gland or gonad having two vital functions: to produce
both sperm and androgens, primarily testosterone. The study aimed to investigate the effect of
tramadol and boldenone injected alone or in combination for 2 months in rats on testicular function.
Materials and Methods: Group 1, normal control; Group 2, tramadol HCl (TRAM) (20 mg/kg bwt.)
(IP); Group 3, boldenone undecylenate (BOLD) (5 mg/kg bwt) (i.m); Group 4, combination of TRAM
(20 mg/kg bwt.) and BOLD (5 mg/kg); respectively for 2 months.
Results: TRAM and BOLD alone and in combination showed deteriorated testicular functions,
lowered serum steroid levels (FSH, LH, and testosterone), elevation in oxidative biomarkers
(MDA & NO) and reduction in GSH and SOD, down-regulation of StaR and HSD17B3 as well as
histopathological testicular assessment using H&E staining revealing massive degenerative changes
in the seminiferous epithelium and vacuolar changes of most of the spermatogenic stages in both
TRAM and BOLD groups. PAS stain showed an intensive reaction in the interstitial tissue between
the tubules in the TRAM group. Masson trichrome stain showed abundant collagen fiber deposits in
the tunica albuginea with congested BV in the TRAM group.
Conclusion: The study illuminated the hazard of administration of these drugs for a long period as
well as the prominent deleterious effects reported on concurrent use of both drugs.
Forbidden in some countries due to its proven toxicity to humans, chlorpyrifos (CPF) still stands as an organophosphate pesticide (OP) highly used worldwide. Cardiotoxicity assessment is an unmet need in pesticide regulation and should be deeply studied through different approaches to better inform and generate an appropriate regulatory response to OP use. In the present study, we used our 4-week intermittent OP exposure model in rats to address the CPF effects on cardiac morphology allied with cardiovascular functional and biomolecular evaluation. Rats were intermittently treated with CPF at doses of 7 mg/kg and 10 mg/kg or saline (i.p.) and assessed for cardiac morphology (cardiomyocyte diameter and collagen content), cardiopulmonary Bezold-Jarisch reflex (BJR) function, cardiac autonomic tone, left ventricle (LV) contractility, cardiac expression of NADPH oxidase (Nox2), catalase (CAT), superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2) and cardiac levels of advanced oxidation protein products (AOPP) and thiobarbituric acid reactive substances (TBARS). Plasma butyrylcholinesterase (BuChE) and brainstem acetylcholinesterase (AChE) were also measured. Intermittent exposure to CPF induced cardiac hypertrophy, increasing cardiomyocyte diameter and collagen content. An impairment of cardioinhibitory BJR responses and an increase in cardiac vagal tone were also observed in CPF-treated animals without changes in LV contractility. CPF exposure increased cardiac Nox-2, CAT, SOD1, and TBARS levels and inhibited plasma BuChE and brainstem AChE activities. Our data showed that intermittent exposure to CPF induces cardiac hypertrophy together with cardiovascular reflex impairment, imbalance of autonomic tone and oxidative stress, which may bring significant cardiovascular risk to individuals exposed to OP compounds seasonally.
In our present work, some novel substituted 4-phenyl-5-vinylpyrrolidin-2-one derivatives were designed, synthesized, and evaluated for their γ-aminobutyric acid-aminotransferase (GABA-AT) inhibition and in-vivo anticonvulsant activity. Among all the synthesized derivatives, compound 7f was observed as the most potent and competitive inhibitor of GABA-AT (IC50 = 46.29 ± 3.19 µM, Ki = 0.106 ± 0.004 μM). The in-vivo anticonvulsant activity against maximum electroshock (MES) and PTZ, induced seizures test of compound 7f, was observed very significantly (P < 0.05) in comparison with standard Vigabatrin and have shown an increase in the level of GABA in the cortex region of the brain. The ex-vivo studies have also suggested reduced tissue necrosis. Finally, In-silico molecular docking and dynamics studies of compound 7f have shown that it forms desired amino acid residue interactions with the GABA-AT and was stable for 50 ns in the active site pocket of the enzyme.
The effectiveness of head-only electrical stunning of broilers, with a root mean square (RMS) current of 100 or 150 mA delivered using either 50, 400 or 1500 Hz sine wave alternating current (AC), was investigated. The changes occurring in the spontaneous electroencephalogram (EEG) were evaluated using Fast Fourier Transformations (FFT) to determine the impact of the amount and frequency of stunning current on total (2-30 Hz) and relative (13-30 Hz) power contents in the EEG. Induction of epileptiform activity and reduction in the EEG power contents to less than 10% of pre-stun levels from the end of epileptiform activity were used as indicators of effective stunning. The duration of unconsciousness and insensibility was determined on the basis of the return of EEG power contents. In addition, the changes occurring in somatosensory evoked potentials (SEPs) were subjectively evaluated to determine the impact of stunning treatments. The results of ANOVA (repeated measures) showed statistically significant effects of interactions between the current frequencies, amount of current and repeated measures on changes in EEG power contents (P<0.001). Stunning broilers with 150 mA delivered using 50 Hz resulted in EEG changes that were indicative of more pronounced neuronal inhibition following epileptiform activity and also lasted longer than was the case when broilers were stunned with 150 mA delivered using 400 Hz. Stunning broilers with 100 mA delivered using 50 Hz resulted in changes very similar to those observed after stunning with 150 mA of 50 Hz, but which lasted for a relatively shorter time. However, these changes were more pronounced and lasted longer than did stunning with 100 mA delivered using 400 Hz. The effects of stunning broilers with 150 mA of 400 Hz were similar to those found after stunning with 100 mA of 50 Hz. By contrast, stunning broilers with 100 mA of 1500 Hz failed to fulfil the criteria set out in this study. Stunning of broilers with 150 mA of 1500 Hz induced epileptiform activity but failed to reduce EEG power contents to less than 10% of pre-stun levels. Therefore, the stunning of broilers with 100 or 150 mA of 1500 Hz may not be adequate to avoid pain and suffering during slaughter. Thus, minimum currents of 100, 150 and 200 mA should be delivered whilst using 50, 400 and 1500 Hz, respectively, to achieve effective electrical stunning in broilers. Severing of the carotid arteries in the neck following head-only electrical stunning, and high frequency (>125 Hz) electrical water bath stunning of broilers should also become a statutory requirement to prevent the return of consciousness during bleeding.
Stunning efficiency of a pulsed direct current was assessed regarding the effect on the electroencephalogram (EEG) and physical reflexes. Four hundred sixty-seven broilers (males and females) were stunned in an electrified waterbath with 60, 80, 100, 120, and 150 mA at frequencies of 70, 100, 200, 400, 800, and 1,500 Hz. Stunning time was 10 s. The EEG recordings lasted for 120 s poststun and simultaneously the occurrence of breathing, spontaneous eye blinking, corneal reflex, and wing flapping was recorded. The EEG records were assessed regarding a profound suppression to less than 10% of the prestun brain power in 2 brain frequency bands, 2 to 30 Hz and 13 to 30 Hz. The EEG results showed a significant effect of stunning frequency for all analyzed parameters. Stunning frequencies of 800 and 1,500 Hz did not achieve adequate stunning results. With a minimum stunning current of 120 mA at frequencies of 70 or 100 Hz or 150 mA at 200 Hz, more than 80% of the animals did not resume breathing. Currents of 80 and 100 mA at 70 or 100 Hz achieved unconsciousness in more than 90% of the birds and birds recovered within 30 to 40 s poststun. Epileptiform activity was found in a relatively low proportion of EEG traces. This could be explained by the long stunning time of 10 s, in which epileptiform activity might have occurred already before the start of EEG recording. Direct current stunning causes less cardiac arrest during stunning, but occurrence of breathing seems more related to cardiac function than to consciousness. A maximum of 30% corneal reflexes and spontaneous eye blinking seems acceptable with a maximum of 15% spontaneous blinking at 15 s poststun. Fourty percent of wing flapping occurred in all effectively stunned groups. Direct current seems to have a different effect on male and female broilers because significantly more male broilers showed reflexes, whereas simultaneously the likelihood of profound EEG suppression was higher. Further investigation of this effect is necessary.
Abstract Level of consciousness at the end of life in critically ill patients is poorly characterized. We report a case series of seven patients who were neurologically intact before the decision to withdraw care due to extensive systemic critical illness. As part of our end-of-life care protocol, bispectral index (BIS) monitor (Aspect Medical Systems, Newton, MA) or SEDline (Hospira, Lake Forest, IL) monitoring devices are placed on each patient to ensure adequate comfort. Both monitoring systems use an integer-based system (BIS or PSI, respectively) to reflect the level of consciousness/effect of anesthesia. In each case, loss of blood pressure, as monitored by indwelling arterial line, was followed by a decline is BIS/PSI activity followed by a transient spike in BIS/PSI activity that approached levels normally associated with consciousness. This spike in electroencephalogram (EEG) activity had short duration and the activity then declined to a level of activity associated with burst suppression. In one case of a patient who had a SEDLine device, we were able to capture and analyze the raw EEG signal, and confirm that the EEG waveform was not artifact, and in fact a high frequency waveform was present during the spike activity. We speculate that this level of BIS/SEDline activity is related to the cellular loss of membrane polarization due to hypoxemia. We further speculate that since this increase in electrical activity occurred when there was no discernable blood pressure, patients who suffer "near death" experiences may be recalling the aggregate memory of the synaptic activity associated with this terminal but potentially reversible hypoxemia.
Die unversehrte Hirnrindenoberfläche ist bei Ratten gegen eine durch Thermokoagulation zerstörte Rindengegend um etwa 20 mV positiv. Bei totaler Hirnanoxie oder Ischämie beginnt sich diese Polarität erst nach einigen Minuten rasch zu vermindern. Die Latenz der Terminaldepolarisation (Leão, 1947) nähert sich der Latenz irreversibler Anoxieschäden der Hirnrinde. Es wird der Verlauf der Terminaldepolarisation bei narkotisierten Ratten beschrieben, welche auf verschiedene Arten getötet werden (Erstickung, N2-Anoxie, Dekapitation, NaCN-Vergiftung). Die Halbwerte der Terminaldepolarisation werden bei hypothermischen Ratten (21°C) um etwa 2,5 min später erreicht als bei normothermischen Tieren. Während die Hirnrindepolarität normothermischer Ratten nach 15 min Ischämie den Nullwert erreicht, bleibt in derselben Zeit bei den abgekühlten Tieren noch eine residuelle Polarität erhalten. In einem mit isotonischer Lösung von MgCl2 oder CaCl2 behandelten Rindengebiet treten die einzelnen Phasen der durch NaCN verursachten Depolarisation um etwa 4 min später ein als im unbehandelten Cortex. Es wurden jene Schwellenkonzentrationen von MgCl2 und CaCl2 bestimmt, welche die Depolarisationslatenz signifikant verlängern. Die Terminaldepolarisation wird als ein neues Kriterion für die Überlebenszeit der Hirnrinde empfohlen, das der Wiederbelebungszeit näher steht als die bisher verwendeten Kriterien (z. B. das Verschwinden der elektrischen Spontanaktivität).
We present a case series of increased bispectral index values during donation after cardiac death (DCD). During the DCD process, a patient was monitored with processed electroencephalogram (EEG), which showed considerable changes traditionally associated with lighter planes of anesthesia immediately after withdrawal of care. Subsequently, to validate the findings of this case, processed EEG was recorded during 2 other cases in which care was withdrawn without the use of hypnotic or anesthetic drugs. We found that changes in processed EEG immediately after withdrawal of care were not only reproducible, but can happen in the absence of changes in major electromyographic or electrocardiographic artifact. It is well documented that processed EEG is prone to artifacts. However, in the setting of DCD, these changes in processed EEG deserve some consideration. If these changes are not due to artifact, dosing of hypnotic or anesthetic drugs might be warranted. Use of these drugs during DCD based primarily on processed EEG values has never been addressed.
The relative humaneness of asphyxia and decapitation was objectively evaluated in rats by EEG monitoring. EEG activation (low voltage, fast activity) was considered to indicate discomfort, pain, and affective responses to euthansia. Such activation was present 37.3 plus or minus 7.5 sec after asphyxia and 13.6 plus or minus 4,6 sec after decapitation. Decapitation was also characterized by an immediate large, and relatively long-lasting, ultra-slow voltage, detected by non-polarizable scalp electrodes. Isoelectric activity (death) occurred 69.4 plus or minus 9.9 sec after onset of asphyxia and 27.2 plus or minus 4.4 sec after decapitation.
Rapid euthanasia of laboratory rodents without the use of anesthesia is a necessary research technique whenever there is the likelihood of anesthesia or stress interfering with the chemistry of the tissues under investigation. Decapitation has long been the procedure of choice under such circumstances. Recently, however, the American Veterinary Medical Association (AVMA) panel on euthanasia recommended that decapitation be avoided on the grounds that the decapitated head may be conscious and suffering for as much as 15 seconds. The panel further recommended that if decapitation was scientifically necessary, the decapitated head be immediately immersed in liquid nitrogen. These AVMA guidelines now enjoy regulatory status; the recommendation that decapitation be avoided has thus caused considerable difficulty for all research requiring rapid, anesthesia-free collection of tissues. The scientific validity of these recommendations is consequently a matter of great practical as well as theoretical importance. The decision to discourage decapitation appears to have been based on a single literature report claiming that the EEG of the decapitated head revealed conscious suffering for more than 10 seconds (Mikeska and Klemm 1976). This review carefully examines the scientific literature on this subject. It is concluded that the report by Mikeska and Klemm of EEG activation in the decapitated head is correct, but that this phenomenon is also seen when the decapitated head is under deep anesthesia, and in normal brains under ether anesthesia or during REM sleep. Hence these findings do not demonstrate either consciousness or the perception of pain.(ABSTRACT TRUNCATED AT 250 WORDS)
The question of humaneness of decapitation per se has been considered. The time required for the oxygen tension in decapitated rat brain to decline to a level at which the brain becomes unconscious was estimated to be 2.7 sec. Assuming that decapitation is a powerful arousal stimulus and that the resulting EEG activation (low voltage, fast activity) indicates a conscious awareness of pain and distress the maximum time the pain and distress could be perceived would be 2.7 sec. Hence, decapitation of rats per se may be considered humane.
It has been debated whether or not decapitation of conscious animals is a humane procedure. This problem may be clarified on the basis of recent research that has indicated that neocortical low voltage fast activity (LVFA) and hippocampal rhythmical slow activity (RSA) can result from activity in either the cholinergic corticipetal projections from the basal forebrain or the serotonergic corticipetal projections from the brainstem. These inputs appear to produce, respectively, atropine-sensitive LVFA and RSA and atropine-resistant LVFA and RSA. In waking animals, atropine-resistant LVFA and RSA occur only in close correlation with motor activities such as spontaneous changes in posture, walking or struggling (Type 1 behavior). Painful stimuli readily elicit both Type 1 behavior and LVFA and RSA in atropine-treated rats. Atropine-sensitive LVFA and RSA may occur in anesthetized as well as in conscious animals, but atropine-resistant LVFA and RSA are generally absent during anesthesia. In the experiments reported here, rats were decapitated: (1) in the normal waking state; (2) after pretreatment with atropine or scopolamine; or (3) following induction of anesthesia with ethyl ether. Clear hippocampal RSA and neocortical LVFA were observed in conditions 1 and 3 but not in condition 2. It is concluded: (A) that atropine-sensitive LVFA and RSA are not good indices of conscious perception of pain since these waveforms occur during anesthesia as well as in the waking state; and (B) that the cerebral reaction to decapitation does not resemble the usual cerebral reaction to painful stimuli. This is consistent with the view that decapitation is not inhumane.
