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Published in Philip Winn, Dictionary of Biological Psychology, 2003
(from Greek, para: beside, biosis: a type of life) Parabiosis is the joining of two organisms (at any stage in development) occurring naturally or achieved through surgical intervention. It is not a common state. The best known natural condition is that of parabiotic twins, colloquially known as SIAMESE TWINS. This is a developmental condition in which there has been incomplete separation of MONOZYGOTIC TWINS during development, leaving them joined and possibly sharing organ functions. In experimental studies, parabiotic animals have been surgically created. For example, rats have been joined symmetrically so that parts of their intestines are crossed: food eaten by one rat will pass through its GASTROINTESTINAL SYSTEM but will then cross into the other rat for a short passage before returning to the original animal. In this way it was thought that one could determine the functions of discrete sections of the digestive tract on FEEDING and SATIETY. It is not a common procedure.
Energy balance and its regulation
Published in Geoffrey P. Webb, Nutrition, 2019
Early indirect evidence for the existence of such a satiety hormone (now called leptin) came from the work of Coleman (1973) using two types of genetically obese mice. Obese (ob/ob) and diabetes (db/db) are two forms of genetic obesity in mice. Both ob/ob and db/db mice inherit a very severe obesity associated with diabetes. On a similar genetic background, the two syndromes are practically identical and yet are caused by mutations at different gene loci. Coleman proposed that in the ob/ob mouse the genetic defect is in the leptin (satiety hormone) gene leaving them unable to produce this satiety hormone (leptin) and making their appestat unable to detect any fat stores. As a consequence of this, they overeat and get very fat. He suggested that in the db/db mouse, the abnormal protein is one that allows the appestat to respond to leptin (the leptin receptor). The db/db mouse would thus produce lots of leptin because they have lots of fat in their adipose tissue. However, without any leptin receptor, their appestat cannot detect the leptin and so once again they cannot sense any fat stores and so they overeat. At this time, leptin had not been discovered and was a purely hypothetical hormone. These suggestions were the result of an ingenious series of parabiosis experiments; these are experiments where pairs of animals are surgically linked together so that hormones and other substances can pass between their blood systems. The results obtained from four of these parabiotic pairings are explained in Table 8.1.
Mouse parabiosis model promotes recovery of lymphocytes in irradiated mice
Published in International Journal of Radiation Biology, 2021
Tong Yuan, Xiaodan Han, Huijun Liu, Junling Zhang, Saijun Fan
Heterochronic parabiosis is widely used in the field of aging research. Young and old mice were connected to evaluate the impact of the circulatory environment on aging-related processes. The study of the parabiotic model provides a basis for understanding the epigenetic regulation of cells and plays an important role in exploring the mechanism of aging. These studies have shown that a young circulatory environment plays an important role in improving the cognitive functions of the nervous system in aged mouse (Villeda and Wyss-Coray 2013; Villeda et al. 2014) and improving the functions of aging muscles (Conboy et al. 2005; Brack et al. 2007; Sinha et al. 2014), the thymus (Kim et al. 2015), the heart (Loffredo et al. 2013), liver (Conboy et al. 2005), and the spinal cord (Ruckh et al. 2012). Similar research has been performed in the field of radiation injury, and the survival rate of mice with lethal abdominal irradiation can be significantly increased by parabiosis. The reason for this result may be attributed to the support of normal mice fluid and the electrolyte balance provided by the non-irradiated mice; in addition, hematopoietic support from shielded mice may help these mice survive (Carroll and Kimeldorf 1967). However, the exact radio-protective mechanism has not been studied.
From leptin to lasers: the past and present of mouse models of obesity
Published in Expert Opinion on Drug Discovery, 2021
Joshua R. Barton, Adam E. Snook, Scott A. Waldman
Douglas Coleman and the researchers at Jackson Labs speculated that loss of a ‘circulating factor’ could be the cause of the obesity and diabetes in these mouse models [18]. The strongest evidence for ob and db mutations causing obesity through a circulating factor came from pioneering parabiosis experiments. Parabiosis is the surgical joining of two animal’s circulatory systems, and began to be used experimentally at the turn of the 20th century [19]. By the late 1960s parabiotic studies were in their heyday, employed by almost every field of biomedical research [20]. Parabiosis between healthy and diseased rodents was used to determine if humoral factors from a healthy mouse could rescue the diseased mouse (for example returning to healthy blood pressure, or recovering from radiation) [20]. Parabiosis was then the natural step to identify the ‘circulating factor’ that linked ob and db mutations to obesity.
How necessary are animal models for modern drug discovery?
Published in Expert Opinion on Drug Discovery, 2021
Parabiotic animals are surgically adjoined animals that share single, common physiological systems, most notably the circulatory system. The technique has been successfully employed in a variety of research areas, including studies of obesity, aging, stem cell research, tissue regeneration, diabetes, organ transplantation, tumor biology, endocrinology, etc., and all of these study areas have had an impact on drug discovery, research, and development. This model has been used to investigate several complicated physiological problems; however, important parameters of recovery and exchange kinetics are not well characterized, which limits its experimental use and interpretation of results [16].