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Journal ArticleDOI

The effects of the acetic acid “pain” test on feeding, swimming, and respiratory responses of rainbow trout (Oncorhynchus mykiss): A critique on Newby and Stevens (2008)

15 Jan 2009-Applied Animal Behaviour Science (Elsevier)-Vol. 116, Iss: 1, pp 96-97

TL;DR: (2008).

Abstract(2008). The effects of the acetic acid " pain " test on feeding, swimming, and respiratory responses of rainbow trout (Oncorhynchus mykiss).

Topics: Rainbow trout (69%)

Summary (1 min read)

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Summary

  • The authors also used a completely different housing design where fish where held in barren, cylindrical tanks rather than standard, rectangular tanks with gravel.
  • If the tanks are cylindrical without flat surfaces or gravel, there is no substrate for the animals to perform these behaviours.
  • The authors research has also demonstrated that rainbow trout do not perform anomalous behaviours or exhibit such high physiological alterations in a barren environment as they do in an enriched environment.
  • This most likely led to stress-induced analgesia since high cortisol results in the release of betaendorphin in fish (van den Burg et al., 2005) and, therefore, no suspension in feeding or performance of pain-related behaviours was observed as pain would be reduced centrally.
  • The ethical guidelines followed by this journal state that ''Procedures with animals that may cause more than momentary or minimal pain or distress should be performed with appropriate sedation, analgesia, or anesthesia in accordance with accepted veterinary practice.

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WBI Studies Repository WBI Studies Repository
1-15-2009
The effects of the acetic acid “pain” test on feeding, swimming, The effects of the acetic acid “pain” test on feeding, swimming,
and respiratory responses of rainbow trout (Oncorhynchus and respiratory responses of rainbow trout (Oncorhynchus
mykiss): A critique on Newby and Stevens (2008) mykiss): A critique on Newby and Stevens (2008)
Lynne U. Sneddon
University of Liverpool
Follow this and additional works at: https://www.wellbeingintlstudiesrepository.org/acwp_arte
Part of the Animal Studies Commons, Other Animal Sciences Commons, and the Veterinary
Toxicology and Pharmacology Commons
Recommended Citation Recommended Citation
Sneddon, L. U. (2009). The effects of the acetic acid “pain” test on feeding, swimming, and respiratory
responses of rainbow trout (Oncorhynchus mykiss): a critique on Newby and Stevens (2008). Applied
Animal Behaviour Science, 116(1), 96-97.
This material is brought to you for free and open access
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Letter to the Editor - Applied Animal Behaviour Science
The effects of the acetic acid ‘‘pain’’ test on feeding, swimming, and respiratory responses of rainbow
trout (Oncorhynchus mykiss): A critique on Newby and Stevens (2008)
Newby and Stevens’ (2008) paper ‘‘The effects of the acetic acid ‘pain’ test on feeding, swimming, and
respiratory responses of rainbow trout (Oncorhynchus mykiss)’’ examines the effects of a noxious
stimulus on the behaviour of trout in an attempt to replicate research conducted in my laboratory
(Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008). However, the authors
used a different protocol to the one already published and I would like to respond to some of their points
of discussion to provide scientific explanations for their results using data from my laboratory. The authors
show that swimming behaviour and time to resume feeding are not impaired by administering 2% and 5%
acetic acid subcutaneously but the fish do show the classic rise in respiration rate that has already been
published. Recent electrophysiological investigations from my group have demonstrated that applying 2%
acetic acid topically destroys nociceptor output and the neuron effectively dies (Ashley et al., 2006, 2007).
Therefore, the lack of anomalous rubbing behaviours and resumption of feeding in the Newby and
Stevens (2008) experiment can be attributed to them injecting such a high concentration of acid. If no
nociceptive information is being conducted to the central nervous system then no behavioural changes
will be elicited. This demonstrates the importance of following the experimental design of published
studies to get comparable results (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et
al., 2008).
The authors also used a completely different housing design where fish where held in barren, cylindrical
tanks rather than standard, rectangular tanks with gravel. This may preclude the ability to perform
behaviours such as rocking, where the fish is situated on a gravel substrate and rocks to and fro on either
pectoral fin (Sneddon et al., 2003a), and rubbing where the fish rubs the injection site into the gravel and
sides of tanks (Sneddon, 2003a; Sneddon et al., 2003a; Reilly et al., 2008). If the tanks are cylindrical
without flat surfaces or gravel, there is no substrate for the animals to perform these behaviours. Our
research has also demonstrated that rainbow trout do not perform anomalous behaviours or exhibit such
high physiological alterations in a barren environment as they do in an enriched environment. This data
was presented at the International Fish Biology Conference (2006), the International Applied Animal
Behaviour Conference (2006) and at the Society for Experimental Biology Meeting (2007; Sneddon,
2007). The authors, Newby and Stevens, were present during the 2006 spoken presentation at the
International Fish Biology Conference in St. John’s, Canada and discussed the results with us. Therefore,
they are well aware that these behaviours are not performed in a barren tank set up. We have shown that
barren conditions are more stressful for rainbow trout and result in higher levels of plasma cortisol. These
stressful conditions result in increased preopiomelanocortin (POMC) in the brain of these noxiously
stimulated trout but not in saline injected control fish (Sneddon et al., submitted for publication). POMC is
the precursor to beta-endorphin and the enkephalins which act as natural painkillers within the nervous
system of vertebrates in a mechanism called stress-induced analgesia (McNally, 1999). Therefore, the
stress of being injected with a noxious stimulus using forcible restraint coupled with being held in a barren
environment in the Newby and Stevens (2008) study would lead to high-cortisol levels (Arends et al.,
1999) as demonstrated by the loss of equilibrium in the noxiously stimulated fish. This most likely led to
stress-induced analgesia since high cortisol results in the release of betaendorphin in fish (van den Burg

et al., 2005) and, therefore, no suspension in feeding or performance of pain-related behaviours was
observed as pain would be reduced centrally. Again, it is vital to follow established experimental protocol
to obtain similar results (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008).
The Newby and Stevens’ (2008) study raises a very serious ethical point about the treatment of animals
in pain experimentation. In their protocol, they restrain trout without anaesthesia and insert a hypodermic
needle into a very sensitive area of skin innervated by nociceptors (Sneddon, 2002, 2003b; Ashley
et al., 2006) and administer a high concentration of damaging substance. I believe that this is
not a humane way to administer such a noxious substance given that fish are aquatic animals and
removing them from the water is effectively suffocating them causing significant stress (Arends et al.,
1999). The ethical guidelines followed by this journal state that ‘‘Procedures with animals that may
cause more than momentary or minimal pain or distress should be performed with appropriate
sedation, analgesia, or anesthesia in accordance with accepted veterinary practice. Surgical or
other painful procedures should not be performed on unanesthetized animals’
(http://www.cioms.ch/frame_1985_texts_of_guidelines.htm). I believe that these guidelines should be
adopted in future studies concerning pain in aquatic animals and that appropriate anaesthesia should be
used when administering noxious stimuli.
References
Arends, R.J., Mancera, J.M., Munoz, J.L., Bonga, S.E.W., Flik, G., 1999. The stress response of the
gilthead sea bream (Sparus aurata L.) to air exposure and confinement. J. Endocrinol. 163, 149157.
Ashley, P.J., Sneddon, L.U., McCrohan, C.R., 2007. Nociception in fish: stimulusresponse properties of
receptors on the head of trout Oncorhynchus mykiss. Brain Res. 1166, 4754.
Ashley, P.J., Sneddon, L.U., McCrohan, C.R., 2006. Properties of corneal receptors in a teleost fish.
Neurosci. Lett. 410, 165168.
McNally, G.P., 1999. Pain facilitatory circuits in the mammalian central nervous system: their behavioral
significance and role in morphine analgesic tolerance. Neurosci. Biobehav. Rev. 23, 10591078.
Newby, N.C., Stevens, E.D., 2008. The effects of the acetic acid ‘‘pain’’ test on feeding, swimming, and
respiratory responses of rainbow trout (Oncorhynchus mykiss). Appl. Anim. Behav. Sci. 114, 260269.
Reilly, S.C., Quinn, J.P., Cossins, A.R., Sneddon, L.U., 2008. Behavioural analysis of a nociceptive event
in fish: comparisons between three species demonstrate specific responses. Appl. Anim. Behav. Sci. 114,
248259.
Sneddon, L.U., 2002. Anatomical and electrophysiological analysis of the trigeminal nerve of the rainbow
trout, Oncorynchus mykiss. Neurosci. Lett. 312, 167171.
Sneddon, L.U., 2003a. The evidence for pain perception in fish: the use of morphine as an analgesic.
Appl. Anim. Behav. Sci. 83, 153162.
Sneddon, L.U., 2003b. Trigeminal somatosensory innervation of the head of the rainbow trout with
particular reference to nociception. Brain Res. 972, 4452.
Sneddon, L.U., Braithwaite, V.A., Gentle, M.J., 2003a. Do fish have nociceptors: evidence for the
evolution of a vertebrate sensory system. Proc. R. Soc. Lond. B 270, 11151122.

Sneddon, L.U., Braithwaite, V.A., Gentle, M.J., 2003b. Novel object test: examining pain and fear in the
rainbow trout. J. Pain 4, 431440.
Sneddon, L.U., Edwards, K.L., Ringrose, S., Oulton, L.J., Ashley, P.J., McCrohan, C.R., submitted for
publication. Evidence for central processing of pain in fish: stress induced analgesia.
van den Burg, E.H., Metz, J.R., Spanings, F.A.T., Bonga, S.E.W., Flik, G., 2005. Plasma alpha-MSH and
acetylated beta-endorphin levels following stress vary according to CRH sensitivity of the pituitary
melanotropes in common carp Cyprinus carpio. Gen. Comp. Endocrinol. 140, 210221.
Lynne U. Sneddon*
University of Liverpool, School of Biological Sciences
The BioScience Building, Liverpool L69 7ZB, UK
*Tel.: +44 151 795 4383; fax: +44 151 795 4431
E-mail address: lsneddon@liverpool.ac.uk
Citations
More filters

Journal ArticleDOI
TL;DR: Overall, the behavioral and neurobiological evidence reviewed shows fish responses to nociceptive stimuli are limited and fishes are unlikely to experience pain.
Abstract: We review studies claiming that fish feel pain and find deficiencies in the methods used for pain identification, particularly for distinguishing unconscious detection of injurious stimuli (nociception) from conscious pain. Results were also frequently misinterpreted and not replicable, so claims that fish feel pain remain unsubstantiated. Comparable problems exist in studies of invertebrates. In contrast, an extensive literature involving surgeries with fishes shows normal feeding and activity immediately or soon after surgery. C fiber nociceptors, the most prevalent type in mammals and responsible for excruciating pain in humans, are rare in teleosts and absent in elasmobranchs studied to date. A-delta nociceptors, not yet found in elasmobranchs, but relatively common in teleosts, likely serve rapid, less noxious injury signaling, triggering escape and avoidance responses. Clearly, fishes have survived well without the full range of nociception typical of humans or other mammals, a circumstance according well with the absence of the specialized cortical regions necessary for pain in humans. We evaluate recent claims for consciousness in fishes, but find these claims lack adequate supporting evidence, neurological feasibility, or the likelihood that consciousness would be adaptive. Even if fishes were conscious, it is unwarranted to assume that they possess a human-like capacity for pain. Overall, the behavioral and neurobiological evidence reviewed shows fish responses to nociceptive stimuli are limited and fishes are unlikely to experience pain.

188 citations


Cites background or result from "The effects of the acetic acid “pai..."

  • ...Newby and Stevens were not able to provide a definitive explanation for the differences in results between their study and those of Sneddon et al. but some possible reasons were considered in subsequent discussion (Newby and Stevens 2009; Sneddon 2009)....

    [...]

  • ...In a reply to the Newby and Stevens paper, Sneddon (2009) said that her Sneddon et al. (2003a) study employed 0.1% acid injections and that the 5% injections used by Newby and Stevens would have destroyed nociceptive afferents....

    [...]


Journal ArticleDOI
21 Mar 2014-PLOS ONE
TL;DR: It is indicated that tricaine has no effect on several commonly used behavioural parameters, and that it may be unnecessary to postpone behavioural observations to 30 min after anaesthesia.
Abstract: The pros and cons of using anaesthesia when handling fish in connection with experiments are debated. A widely adopted practice is to wait thirty minutes after anaesthesia before behavioural observations are initiated, but information about immediate effects of a treatment is then lost. This is pertinent for responses to acute stressors, such as acid injection in the acetic acid pain test. However, omission of anaesthetics in order to obtain data on immediate responses will compromise the welfare of fish and contribute to experimental noise due to stress. We therefore tested the effect of tricaine methanesulfonate on the behaviour of zebrafish. We predicted that tricaine (MS 222) would decrease swimming velocity and that the control fish would show an increased level of anxiety- and stress-related behaviours compared to the tricaine group. Following acclimatization to the test tank, baseline behaviour was recorded before immersion in either tricaine (168 mg l(-1), treatment group, N = 8) or tank water (control group, N = 7). Latencies to lose equilibrium and to lose response to touch were registered. The fish was then returned to the test tank, and the latency to regain equilibrium was registered in anaesthetized fish. When equilibrium was regained, and at five, thirty and sixty minutes after the fish had been returned to the test tank, behaviour was recorded. The tricaine fish showed the following responses (mean ± sd): latency to lose equilibrium 22.6 s±3.9; latency to lose response to touch 101.9 s±26.8; latency to regain equilibrium 92.0 s±54.4. Contrary to our predictions, neither treatment caused a change in any of the behaviours registered. This indicates that tricaine has no effect on several commonly used behavioural parameters, and that it may be unnecessary to postpone behavioural observations to 30 min after anaesthesia.

37 citations


Journal ArticleDOI
TL;DR: The observation showing a dose-response relation for morphine using a noxious stimulus supports arguments for its effectiveness as an antinociceptive drug in fish.
Abstract: Jones, S. G., Kamunde, C., Lemke, K., Stevens, E. D. The dose–response relation for the antinociceptive effect of morphine in a fish, rainbow trout. J. vet. Pharmacol. Therap. 35, 563–570. There have been suggestions that analgesics be used by fish researchers. But in the absence of dose–response data for morphine, this suggestion seems imprudent. The purpose of the present study was to develop a dose–response relationship in fish using six doses of morphine. The response (movement of the fins or tail) to a noxious stimulus (electrical shock to the face region) was monitored before and after a dose of morphine intraperitoneally (i.p.). The i.p. dose of morphine ED50 in rainbow trout was 6.7 ± 0.8 mg/kg (n = 12 at each dose). The plasma morphine concentration EC50 was 4.1 ± 1.5 mg/L. In a second experiment, rainbow trout tested with equal amounts of morphine and naloxone (30 mg/kg) showed that the antinociceptive effect of morphine was blocked by naloxone. It has been suggested that stress-induced analgesia has been a confounding factor in some fish studies. However, plasma cortisol levels in our study indicated that stress was not a confounding factor in the present experiments. The ED50 for morphine in fish was higher than that reported for humans or other mammals. Our observation showing a dose–response relation for morphine using a noxious stimulus supports arguments for its effectiveness as an antinociceptive drug in fish.

20 citations


Cites background or result from "The effects of the acetic acid “pai..."

  • ...Our rationale for measuring cortisol was that it has been argued that some of the discrepancies in the literature regarding nociception in fishes could be due to stress-induced analgesia (Newby & Stevens, 2009; Sneddon, 2009)....

    [...]

  • ...We also measured plasma cortisol levels in our experiments because it has been argued that ‘stress-induced’ analgesia is a confounding factor that could explain some of the discrepancies in the literature regarding analgesia in fish (Newby & Stevens, 2009; Sneddon, 2009)....

    [...]



References
More filters

Journal ArticleDOI
TL;DR: This study provides significant evidence of nociception in teleost fishes and demonstrates that behaviour and physiology are affected over a prolonged period of time, suggesting discomfort.
Abstract: Nociception is the detection of a noxious tissue-damaging stimulus and is sometimes accompanied by a reflex response such as withdrawal. Pain perception, as distinct from nociception, has been demonstrated in birds and mammals but has not been systematically studied in lower vertebrates. We assessed whether a fish possessed cutaneous nociceptors capable of detecting noxious stimuli and whether its behaviour was sufficiently adversely affected by the administration of a noxious stimulus. Electrophysiological recordings from trigeminal nerves identified polymodal nociceptors on the head of the trout with physiological properties similar to those described in higher vertebrates. These receptors responded to mechanical pressure, temperatures in the noxious range (more than 40 degrees C) and 1% acetic acid, a noxious substance. In higher vertebrates nociceptive nerves are either A-delta or C fibres with C fibres being the predominating fibre type. However, in the rainbow trout A-delta fibres were most common, and this offers insights into the evolution of nociceptive systems. Administration of noxious substances to the lips of the trout affected both the physiology and the behaviour of the animal and resulted in a significant increase in opercular beat rate and the time taken to resume feeding, as well as anomalous behaviours. This study provides significant evidence of nociception in teleost fishes and furthermore demonstrates that behaviour and physiology are affected over a prolonged period of time, suggesting discomfort.

346 citations


"The effects of the acetic acid “pai..." refers background or result in this paper

  • ...Again, it is vital to follow established experimental protocol to obtain similar results (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008)....

    [...]

  • ...This demonstrates the importance of following the experimental design of published studies to get comparable results (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008)....

    [...]

  • ...…behaviours such as rocking, where the fish is situated on a gravel substrate and rocks to and fro on either pectoral fin (Sneddon et al., 2003a), and rubbing where the fish rubs the injection site into the gravel and sides of tanks (Sneddon, 2003a; Sneddon et al., 2003a; Reilly et al., 2008)....

    [...]

  • ...…the ability to perform behaviours such as rocking, where the fish is situated on a gravel substrate and rocks to and fro on either pectoral fin (Sneddon et al., 2003a), and rubbing where the fish rubs the injection site into the gravel and sides of tanks (Sneddon, 2003a; Sneddon et al., 2003a;…...

    [...]

  • ...…on feeding, swimming, and respiratory responses of rainbow trout (Oncorhynchus mykiss)’’ examines the effects of a noxious stimulus on the behaviour of trout in an attempt to replicate research conducted in my laboratory (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008)....

    [...]


Journal ArticleDOI
TL;DR: The data provide evidence that a stressor-specific activation of the BSC and BPI axes may occur in Sparus aurata, and conclude that air exposure mainly activates the brain-sympathetic-chromaffin cell (BSC) axis.
Abstract: We investigated short-term eVects (up to 24 h) of air exposure and confinement, and long-term eVects (up to 11 days) of confinement, to elucidate signalling pathways in the stress response of gilthead sea bream Sparus aurata L. Plasma glucose and lactate were taken as indicators of sympathetic activation, and AE-melanocyte stimulating hormone (AE-MSH), adrenocorticotrophic hormone (ACTH) and cortisol as indicators of activation of the brain‐ pituitary‐interrenal (BPI) axis. Air exposure for 3 min resulted, within 30 min, in an increase in plasma concentrations of cortisol, AE-MSH, glucose, lactate, osmolality and plasma Na, Cl and Mg. Plasma ACTH and ‚-endorphin and plasma K, Ca and P did not change. We conclude that air exposure mainly activates the brain‐ sympathetic‐chromaYn cell (BSC) axis. In fish confined at a density of 70 kg/m 3 (compared with 4 kg/m 3 in controls), cortisol, ACTH and AE-MSH increased within 1 h, indicating activation of the BPI axis. Plasma glucose, Na, Cl and Mg increased with an 8 h delay compared with the response to air exposure. No changes in plasma lactate, osmolality, K, Ca and P were observed. Long-term confinement induced a biphasic cortisol response with peaks at 1 h and at 2 and 3 days. A gradual increase in plasma ‚-endorphin concentrations peaked at 7 days; the concentration of AE-MSH increased rapidly within 1 h and then declined to control values 4 days after the onset of confinement. No changes in ACTH were detected. Our data provide evidence that a stressor-specific activation of the BSC and BPI axes may occur in Sparus aurata.

304 citations


"The effects of the acetic acid “pai..." refers background in this paper

  • ...I believe that this is not a humane way to administer such a noxious substance given that fish are aquatic animals and removing them from the water is effectively suffocating them causing significant stress (Arends et al., 1999)....

    [...]

  • ...…the stress of being injected with a noxious stimulus using forcible restraint coupled with being held in a barren environment in the Newby and Stevens (2008) study would lead to high-cortisol levels (Arends et al., 1999) as demonstrated by the loss of equilibrium in the noxiously stimulated fish....

    [...]

  • ...Therefore, the stress of being injected with a noxious stimulus using forcible restraint coupled with being held in a barren environment in the Newby and Stevens (2008) study would lead to high-cortisol levels (Arends et al., 1999) as demonstrated by the loss of equilibrium in the noxiously stimulated fish....

    [...]


Journal ArticleDOI
TL;DR: Assessing the acute effects of administering a noxious chemical to the lips of rainbow trout concluded that these pain-related behaviours are not simple reflexes and therefore there is the potential for pain perception in fish.
Abstract: This paper discusses the evidence for pain perception in fish and presents new data on morphine analgesia in fish. Recent anatomical and electrophysiological studies have demonstrated that fish are capable of nociception, the simple detection of a noxious, potentially painful stimulus and the reflex response to this. To prove pain perception, it must be demonstrated that an animal's behaviour is adversely affected by a potentially painful event and this must not be a reflex response. The present study examined the acute effects of administering a noxious chemical to the lips of rainbow trout ( Oncorhynchus mykiss ) to assess what changes occurred in behaviour and physiology. There was no difference in swimming activity or use of cover when comparing the noxiously stimulated individuals with the controls. The noxiously treated individuals performed anomalous behaviours where they rocked on either pectoral fin from side to side and they also rubbed their lips into the gravel and against the sides of the tank. Opercular beat rate (gill or ventilation rate) increased almost double fold after the noxious treatment whereas the controls only showed a 30% increase. Administering morphine significantly reduced the pain-related behaviours and opercular beat rate and thus morphine appears to act as an analgesic in the rainbow trout. It is concluded that these pain-related behaviours are not simple reflexes and therefore there is the potential for pain perception in fish.

294 citations


"The effects of the acetic acid “pai..." refers background or result in this paper

  • ...Again, it is vital to follow established experimental protocol to obtain similar results (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008)....

    [...]

  • ...This demonstrates the importance of following the experimental design of published studies to get comparable results (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008)....

    [...]

  • ...…behaviours such as rocking, where the fish is situated on a gravel substrate and rocks to and fro on either pectoral fin (Sneddon et al., 2003a), and rubbing where the fish rubs the injection site into the gravel and sides of tanks (Sneddon, 2003a; Sneddon et al., 2003a; Reilly et al., 2008)....

    [...]

  • ...…on feeding, swimming, and respiratory responses of rainbow trout (Oncorhynchus mykiss)’’ examines the effects of a noxious stimulus on the behaviour of trout in an attempt to replicate research conducted in my laboratory (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008)....

    [...]

  • ...In their protocol, they restrain trout without anaesthesia and insert a hypodermic needle into a very sensitive area of skin innervated by nociceptors (Sneddon, 2002, 2003b; Ashley et al., 2006) and administer a high concentration of damaging substance....

    [...]


Journal ArticleDOI
TL;DR: Results suggest that nociception captures the animal's attention with only a relatively small amount of attention directed at responding to the fear of the novel object.
Abstract: This study aimed to assess fear responses to a novel object while experiencing a noxious event to determine whether nociception or fear will dominate attention in a fish in novel object testing paradigm. This experimentally tractable animal model was used to investigate (1) the degree of neophobia to a novel object while experiencing noxious stimulation, (2) the response of the fish after removing the fear-causing event by using a familiar object, and (3) the effects of removing the nociceptive response by morphine administration and examining the response to a novel object. Control animals displayed a classic fear response to the novel objects and spent most of their time moving away from this stimulus, as well as showing an increase in respiration rate when the novel object was presented. In contrast, noxiously stimulated animals spent most of their time in close proximity to the novel object and showed no additional increase in respiration rate to novel object presentation. There was evidence of a slight hypoalgesia in noxiously stimulated animals. The responses to familiar objects demonstrated that by familiarizing the animal with the object, fear was removed from the experiment. Both control and noxiously treated animals responded in similar ways to a novel object by spending the majority of their time in close proximity. Treatment with morphine reduced effects of noxious stimulation and appears to be an effective analgesic. After morphine administration, the acid-injected animals showed a neophobic response to a novel object and this was similar to the response of the control fish, with a similar amount of time spent moving away from the object and an increase in ventilation in response to the novel object. Morphine affected the fear response because both groups approached the novel object more quickly than the non-morphine controls. These results suggest that nociception captures the animal's attention with only a relatively small amount of attention directed at responding to the fear of the novel object.

198 citations


"The effects of the acetic acid “pai..." refers background or result in this paper

  • ...Again, it is vital to follow established experimental protocol to obtain similar results (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008)....

    [...]

  • ...This demonstrates the importance of following the experimental design of published studies to get comparable results (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008)....

    [...]

  • ...…behaviours such as rocking, where the fish is situated on a gravel substrate and rocks to and fro on either pectoral fin (Sneddon et al., 2003a), and rubbing where the fish rubs the injection site into the gravel and sides of tanks (Sneddon, 2003a; Sneddon et al., 2003a; Reilly et al., 2008)....

    [...]

  • ...…the ability to perform behaviours such as rocking, where the fish is situated on a gravel substrate and rocks to and fro on either pectoral fin (Sneddon et al., 2003a), and rubbing where the fish rubs the injection site into the gravel and sides of tanks (Sneddon, 2003a; Sneddon et al., 2003a;…...

    [...]

  • ...…on feeding, swimming, and respiratory responses of rainbow trout (Oncorhynchus mykiss)’’ examines the effects of a noxious stimulus on the behaviour of trout in an attempt to replicate research conducted in my laboratory (Sneddon, 2003a; Sneddon, 2007; Sneddon et al., 2003a,b; Reilly et al., 2008)....

    [...]


Journal ArticleDOI
TL;DR: The trigeminal nerve in the rainbow trout, Oncorhynchus mykiss, was examined for the presence of A-delta and C fibres and electrophysiological recordings of evoked activity from the ganglion confirmed the presence, as well as the potential for nociceptive capability in a lower vertebrate.
Abstract: The trigeminal nerve in the rainbow trout, Oncorhynchus mykiss, was examined for the presence of A-delta and C fibres. Sections of the three branches of the trigeminal nerve were found to comprise a range of fibre types including A-delta and C fibres. The size range of the cell bodies of the trigeminal ganglion reflected the fibre range since they correlated with the size range of axons in the nerve branches. Electrophysiological recordings of evoked activity from the ganglion confirmed the presence of these fibre types and the proportion of these mirrored the proportion of fibre types in the anatomical analyses. A-beta fibres were most common followed by A-delta fibres, then A-alpha fibres with C fibres being the fewest fibre type found. In higher vertebrates, A-delta and C fibres in the trigeminal nerve convey both somatosensory and nociceptive information to the brain. The evolutionary significance of these results is discussed as well as the potential for nociceptive capability in a lower vertebrate.

125 citations


"The effects of the acetic acid “pai..." refers background in this paper

  • ...In their protocol, they restrain trout without anaesthesia and insert a hypodermic needle into a very sensitive area of skin innervated by nociceptors (Sneddon, 2002, 2003b; Ashley et al., 2006) and administer a high concentration of damaging substance....

    [...]