GPO: Tank size.

[neurobadger]

In inverts, nociceptors fire in response to immediate noxious stimulation and this firing patter can last minutes, but there does not appear to be ongoing firing after pain or injury without additional stimulation (like poking at bruised tissue).

The numbered list from EU directive is very interesting and looks about perfect to me except that I disagree with 4. Opiods are not the only endogenous analgesics, and the evidence for their presence, at least in molluscs, is not conclusive.

Has anyone ever tried to induce chronic pain in an invertebrate to at least see whether these receptors are capable of firing in the same way that they do in vertebrates with chronic pain?

There seems to be some evidence that met-enkephalin analogues exist in mollusks and that mollusks respond to exogenous opioids (list of citations here Google Scholar ). Whether it is conclusive or not I don't know.

 

[neurobadger]

As for regulations, I think some are needed, and if they are made they should be compulsory not voluntary. Regulations including some or all cephalopods are already operational in several countries and there is no reason that regulation, reasonably and responsibly implemented, need be onerous to the point of making research not worth doing. I support the use of regulations for many invertebrate species, since in almost all cases where a scientist has empirically considered 'does this injurious or noxious experience change the behaviour of this invertebrate in such a way that if a vertebrate behaved similarly, we would consider this evidence of pain or distress?' such evidence has been found. The lack of present regulation for invertebrates stems more from want of looking than negative findings.

What do you mean when you say 'want of looking'?

In any case, I agree.

I have a relative who works at one of the United States's grant-producing bodies for biological sciences, and as I said before if the sort of stuff being said about invertebrates in regard to the paperwork being onerous and the restrictions regulations might impose on research were said about VERTEBRATES today, the vast majority of researchers who work on animals - along with most grant-producing bodies for biological sciences who deal with experiments involving animal subjects - would have faces that look like this:



And I am quite serious about this; animal welfare is RIGOROUSLY enforced where this relative works, and there are steep penalties for animal abuse and neglect.

And none of these regulations impose any real, unreasonable restrictions whatsoever - as far as I am aware - on the research that has been done, as evidenced by the huge diversity of research going on with vertebrate animals in the United States at least. These regulations were not designed to restrict research; they were made with the animals in mind first and foremost and go through considerable review constantly to make sure they tread the right ethical line while not unreasonably preventing new kinds of research.

Pain research is probably a perfect example of where these rules have to be examined constantly, as it inevitably will cause some animal some suffering.

Anyway, my point is that I have no clue what kind of experiment Thales and DWhatley are talking about that a researcher in the community would do that would violate present regulations regarding vertebrate research (especially in sensitive areas such as pain research), if said regulations were modified with the respect to the biology of and implemented for cephalopods.

 

[neurobadger]

The scientific report on nociceptors:

Criterion 4 - Receptors for opioid substances found in the central nervous system,
especially the brain.
Some invertebrates have many of the neurotransmitters that are involved in
vertebrate pain reception and mediation. It has been found that molluscs (Kream et
al., 1980 cited by Greenberg and Price, 1983) and insects (Stefano and Scharrer,
1981 cited by Eisemann et al., 1984; Nunez et al., 1983; Zabala et al., 1984 cited by
Fiorito, 1986) have opioid binding sites or opioid sensitivity. Certainly, there are
many examples of neuropeptides that are involved in vertebrate pain responses being
found in invertebrates (Clatworthy, 1996; Stefano et al., 1998), for example,
enkephalin and endorphins have been found in platyhelminths, molluscs, annelids,
crustaceans and insects (Greenberg and Price, 1983; Fiorito, 1986). As pointed out
by Greenberg and Price (1983), the occurrence of vertebrate pain-related
neuropeptides in invertebrates does not necessarily mean that invertebrates
experience pain; analogous physiological roles in different classes or phyla are not
always carried out by homologous peptides, but it does at least indicate that many
invertebrates might have the physiological capacity to experience pain or an
analogous sensation. In molluscs, naloxone injections (but not other neuroactive
substances) into the sites of severed nerves counteract the migration of haematocytes
in response to the injury, indicating the involvement of opioid peptides in this
response (Clatworthy, 1996). In support of this, injection of a synthetic analogue of
metenkephalin induces the directed migration of haematocytes to the site of injection.
Furthermore, Clatworthy (1996), in discussing the responses of nociceptors to
damaging or potentially damaging stimuli, wrote:
"The enhancement of responsiveness in these sensory neurones following injury or
the induction of a foreign body response is therefore functionally similar to
hyperalgesia, i.e. a heightened sensitivity to painful stimuli, in mammal(s)".
This may be correct but opioids like metenkephalin whose receptors are blocked by
naloxone have roles in a range of physiological processes. Stefano et al., (1998)
reported that some invertebrates contain an opioid precursor, proenkephalin.
Enkelytin, an antibacterial peptide, is found in proenkephalin, exhibiting 98%
sequence identity with mammalian enkephalin. Stefano et al. (1998) suggested that
the function of enkelytin is to attack bacteria and allow time for the immunocytestimulating
capabilities of the opioid peptides to emerge. Furthermore, based on the
similarity of the biochemical and physiological responses, they proposed that pain
itself might be a component of this response. This could be correct but is not proven.

 

[neurobadger]

What would we need to know about opioid secretion in mollusks to know whether they experience suffering or just nociception, if indeed the evidence was conclusive about the presence of opioid neurotransmitters in mollusks? I'm not as familiar with the nociception-to-suffering mechanism.

 

[gjbarord]

Just lost my whole reply!!! Will regroup and try later...

Greg

(Tony, is there a specific time limit allotted to typing a response before you get signed out)