Senescence and the Optic Gland

Discussion in 'Physiology and Biology' started by monty, May 23, 2006.

  1. monty

    monty Colossal Squid Staff Member Supporter

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    I just stumbled over my notes from my "Comparative Nervous Systems" course, which had a section on cephalopods. I just skimmed my notes, and found something interesting:

    "When cephs breed, they stop eating, senesce, and die. removing the optic gland prevents this."

    I'm not sure what the source is (the prof was John Allman, I can probably ask him) but I wonder if removing the optic gland in a pet octopus would prolong its lifespan without reducing its quality of life, if it's a simple surgery like spaying and neutering is for cats and dogs... Anyone know details about this? Nixon and Young report that the optic gland is involved in sexual maturity, but not this particular detail. Hanlon and Messenger describe it a bit, but again, rather non-sepecifically.
     
  2. Tintenfisch

    Tintenfisch Architeuthis Staff Member Moderator

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    Interesting idea, although surely removal of the optic gland would also have some serious consequences for the octopus' vision, if not general health? A quick search on CephBase (keyword 'optic') yielded about 60 refs, of which these look the most relevant:


    Wodinsky J. 1977. Hormonal inhibition of feeding and death in Octopus: Control by optic gland secretion. Science. 198 (4320) : pp.948-952

    Boyle P.R. and R.S. Thorpe 1984. Optic gland enlargement and female gonad maturation in a population of the octopus Eledone cirrhosa: a multivariate analysis. Marine Biology. 79 : pp.127-132

    Nishioka R.S., Bern H.A. and D.W. Golding 1970. Innervation of the Cephalopod optic gland. In: Aspects of Neuroendocrinology. Barqmann W. and B. Scharrer, ed. : pp.47-54

    O'Dor R.K. 1973. Yolk protein synthesis in the ovary of Octopus vulgaris and its control by the optic gland gonadotropin. Journal of Experimental Marine Biology and Ecology. 59 : pp.665-674

    Rowe L.V. and D.R. Idler 1977. In vitro stimulation of protein synthesis in squid ovary by optic gland extract. General and Comparative Endocrinology. 32 : pp.248-251

    Saidel W.M. 1979. Relationship between photoreceptor terminations and centrifugal neurons in the optic lobe of octopus. Cell and Tissue Research. 204 : pp.463-472

    Saidel W.M. 1982. Connections of the octopus optic lobe: An HRP study. The Journal of Comparative Neurology. 206 : pp.346-358

    Wells M.J. 1960. Optic glands and the ovary of octopus. Symposia of the Zoological Society of London. 2 : pp.87-107

    (and a lot more by Wells)
     
  3. monty

    monty Colossal Squid Staff Member Supporter

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    Thanks for the refs. My impression is that the removal might not have a direct impact on the visual system, since I believe it's so named because it's adjacent to the optic lobes more than directly related, although I guess it's a neurally controlled endocrine gland, so apparently (from Hanlon and Nixon) Wells & Wells (1959) showed a "hormonal influence on maturation of the gonads" had the pathway:

    light->eye->optic lobe->subpedunculate lobe->optic gland->gonad, with the first 4 links neural and inhibitory, and the last hormonal and excitatory. So apparently darkness stops neural inhibition of the gland's hormone secretion, and triggers the sexual reproductive maturity somehow. I wonder what the time scale of this is-- maybe when the octo has managed to seal its den off from light completely, this mechanism decides it's safe to lay eggs? This is all in O. Vulgaris, by the way... apparently there is some evidence that Sepia is different, at least in that "more than one hormone" may be involved.

    Given where these glands are in the brain, I guess it's probably too delicate a surgery to do for pets, anyway...
     
  4. cuttlegirl

    cuttlegirl Colossal Squid Supporter Registered

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  5. monty

    monty Colossal Squid Staff Member Supporter

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    Thanks, that's a great overview, and seems to point to the specific experiment my prof was discussing. They even seem to think it's worth investigating for lifespan-extension in public aquaria, so "cool! I had the same idea is cool smart expert teuthologists!" :grin:
     

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