The lifespan of an organism depends on ATP pro- duction, among other factors [1]. The initial substrate in ATP synthesis is glucose. The levels and activities of glu- coneogenesis and glycolysis enzymes are controlled so that both pathways are not activated at the same time. The rate of glycolysis is regulated by the concentration of glu- cose, whereas the rate of gluconeogenesis – by the con- centrations of lactate and other glucose precursors [2]. In ISSN 0006-2979, Biochemistry (Moscow), 2019, Vol. 84, No. 4, pp. 435-440. © Pleiades Publishing, Ltd., 2019. Published in Russian in Biokhimiya, 2019, Vol. 84, No. 4, pp. 580-586. 435 Abbreviations: DOMS, delayed onset muscle soreness; GLM, multivariate covariance generalized linear model; LDH, lactate dehy- drogenase. * To whom correspondence should be addressed. Comparison of Lactate Dehydrogenase Activity in Hive and Forager Honeybees May Indicate Delayed Onset Muscle Soreness – Preliminary Studies A. Strachecka 1,a *, M. Grzybek 2,3,b , A. A. Ptaszynska 4,c , A. Los 1,5,d , J. Chobotow 6,e , and R. Rowinski 7,f 1 Institute of Biological Basis of Animal Production, Faculty of Biology, Animal Sciences and Bioeconomy, University of Life Sciences in Lublin, 20-950 Lublin, Poland 2 Department of Tropical Parasitology, Medical University of Gdansk, 81-519 Gdynia, Poland 3 Department of Zoology, Animal Ecology & Wildlife Management, Faculty of Biology and Animal Breeding, University of Life Sciences in Lublin, 20-950 Lublin, Poland 4 Department of Botany and Mycology, Institute of Biology and Biochemistry, Faculty of Biology and Biotechnology, Maria Curie-Sklodowska University, 20-033 Lublin, Poland 5 Institute of Nature Conservation, Polish Academy of Sciences, 31-120 Cracow, Poland 6 Zoological Museum/Laboratory, Institute of Biology and Biochemistry, Faculty of Biology and Biotechnology, Maria Curie-Sklodowska University, 20-033 Lublin, Poland 7 Department of Tourism and Recreation, Faculty of Agrobioengineering, University of Life Sciences in Lublin, 20-950 Lublin, Poland a e-mail: aneta.strachecka@up.lublin.pl b e-mail: grzybek.genetics@gmail.com c e-mail: anetaptas@wp.pl d e-mail: los-aleksandra@o2.pl e e-mail: jacek.chobotow@umcs.lublin.pl f e-mail: badaniaawf@wp.pl Received May 30, 2018 Revised November 27, 2018 Accepted November 27, 2018 Abstract—Active skeletal muscles produce lactate. H + is generated during lactate neutralization in the Cori cycle, which leads to muscle acidosis and soreness (the so-called Delayed Onset Muscle Soreness, DOMS) in vertebrates. The aim of the study was to determine the activities/concentrations of compounds involved in the Cori cycle in worker and forager bees. Muscles, fat bodies, and hemolymph from 1- and 14-day-old workers and foragers were collected and assayed for the protein, lactate, glucose, NAD + , and NADH concentrations and lactate dehydrogenase (LDH) activity. Both lactate concentration and LDH activity in the hemolymph, muscles, and fat bodies increased with age. The concentrations of NAD + and NADH in the tis- sues decreased with ageing/senescence, whereas protein concentrations increased until day 14 of bee’s life and then decreased in foragers. The concentration of glucose decreased in the hemolymph and muscles and increased in the fat bodies. Elevated lactate concentrations in foragers may indicate transition from the aerobic to the anaerobic phase and development of meta- bolic acidosis that may eventually lead to muscle damage/soreness and shorter lifespan. When analyzing flight dynamics, load mass, and bee behavior, changes in the concentrations of Cori cycle compounds should be taken into account. DOI: 10.1134/S0006297919040114 Keywords: Cori cycle, fat body, honeybee workers, lactate, muscle, sores