How micro-PET images of octopuses may reveal alternative regenerative medicine methods

Published online in the Journal of Nuclear Medicine on March 9, a study assessed common regeneration principles in octopuses to potentially identify alternative therapeutic approaches in regenerative medicine. 

According to the study, researchers sought to develop a new method to efficiently administer the radiopharmaceutical 18F-Fludeoxyglucose (18F-FDG) in an octopus and micro-positron emission tomography (micro-PET) bio-distribution for assay for the characterization of glucose metabolism in animal, and ultimately human, body organs and regenerating tissues.   

"Their [cephalopods] behavioral capabilities and highly evolved neural system have prompted their recent inclusion in the list of species undergoing European Union ethical regulation," wrote lead author Letizia Zullo from the Center for Synaptic Neuroscience and Technology at the Italian Institue of Technology in Genoa. "In this perspective, there is an increasing need for minimally invasive experimental approaches that, by reducing the impact of surgery, will allow function investigation on behavior, neurophysiology and body function of live cephalopods."  

A total of seven octopuses of either sex were collected from the Liguria coast between 2013 and 2017. Two of the seven had one arm dissected for regenerative analysis purposes and were anesthetized and injected with 18-30 MBq of isosmotic (18F-FDG). After roughly 50 minutes, all seven octopuses were sacrificed in accordance with European Union ethical regulation standards and underwent full body mirco-PET scans. Researchers then collected internal organs of the animals to confirm image interpretations.

Researchers concluded that micro-PET scanning successfully administered full body images of each octopus. In particular, high mantle mass radioactivity facing a low tracer uptake in the arms were identified, according to study results. The brain, optic lobes, and arms then were measured in each octopus for 18F-FDG uptake. Overall, levels of 18F-FDG uptake in each octopus were up to three times higher in the regenerating arms at the level of other highly proliferating areas, the researchers wrote. These high levels, they explained, reflect the presence of actively dividing cells in blastema, peripheral nervous tissue and muscles characteristic of regenerating tissues. 

"Administration of a radioactive compound through the anterior vena cava has to be preferred in bio-distribution studies and this methodology can be employed of the assessment of regenerating events occurring at various regions of the animal body," Zullo et al. wrote. "This study represents a first step toward the use of nuclear medicine imaging techniques in new emerging research areas such as neurobiology of invertebrates and animals with particular relevance in the field of regenerative medicine."