Monday, 22 July 2019 10:13

Hannover: Locust embryos as developmental toxicology test system Featured

Scientists from the University of Veterinary Medicine in Hannover have developed a system to test for development toxicity, with which they want replace rodents. Anstead of rodents they want to use locust embryos.


With the new system, chemicals such as pesticides can be examined to determine whether they have an influence on the correct interconnecting of the nerve cells or whether this process has been disrupted. For this purpose the locust embryo is cultivated with the test chemical and investigated by fluorescence microscopy methods to determine how the pioneer neurons develop in the tissue, grow out and, if necessary, make mistakes in finding their path.

The locust test system was developed by scientists from the Institute of Physiology and Cell Biology at the University of Veterinary Medicine Hanover. The work group is headed by Professor Gerd Bicker. Here, the research focuses on the investigation of leading signals such as semaphorins, a class of membrane-associated proteins that control where nerve cell processes grow in a developing brain structure.

Semaphorins are highly conserved, so that the observed mechanisms can be studied on insects. The European Animal Experiments Directive only mentions cephalopods and vertebrates. According to Recital 13 of Directive EU/63/2010, species have to be selected "... with the least ability to feel pain, suffering or distress...".

The German Animal Welfare Act mentions only cephalopods and decapods as invertebrates. However, in § 8a (4) it has been said that experiments on invertebrates other than cephalopods and decapods (in which the ability to suffer has already been proven) would have to be reported to the competent authority if these animals have appropriate species specific ability to suffer  from the experimental effects comparable to vertebrates and if it would be necessary to protect them. In a recent study (1) it was observed that insects are capable of chronic pain sensitivity. There are older studies from the 90s (2,3) which point to something similar to pain sensitivity in crickets. Opioid peptides and opiate receptors are believed to be present. Insects have a rope ladder nervous system on which the so-called upper ganglion is located on the top, arranged in pairs which could maybe analogous to the brain of vertebrates.

Initial investigations have shown that the test system is highly sensitive to pesticides, calcium channel blockers and substances influencing the structure of the cytoskeleton.

The scientists are now working on the standardization of the test system.

The researchers have presented their development in the journal ALTEX: Gregor A. Bergmann, Sarah Frömbling, Nina Joseph, Karsten Bode, Gerd Bicker, Michael Stern (2019). An Intact Insect Embryo for Developmental Neurotoxicity Testing of Directed Axonal Elongation. ALTEX, DOI:10.14573/altex.1901291

Source:
https://idw-online.de/de/news718940
 
About the pain sensation of insects:
(1) https://www.scinexx.de/news/biowissen/auch-insekten-fuehlen-chronische-schmerzen/
(2) V. E. Dyakonova, D. Schurmann, D. A. Sakharova: Effects of serotonergic and opioidergic drugs on escape behaviors and social status of male crickets. In: Natural Sciences. Volume 86, 1999, S. 435–437.
(3) N. Zabala, M. Gomez: Morphine analgesia, tolerance and addiction in the cricket, Pteronemobius. In: Pharmacology, Biochemistry and Behaviour. Volume 40, 1991, pp. 887-891.