Artificial Rearing of Mouse Pups: Development of a Mouse Pup in a Cup Model

Abstract

Artificial rearing of rat pups has been used in the investigation of the neonatal gut. We propose to adapt the model of artificially rearing rat pups for use in mouse pups, thereby allowing the use of transgenic animals for our research. We hypothesized that gastrostomy catheters may be placed successfully into neonatal mouse pups and that the pups may be artificially reared without significant alterations in their growth or intestinal development. Gastrostomy tubes are placed into 5-d-old mouse pups [artificially reared (AR); n ϭ 32], and the mice are fed rodent milk substitute. Littermate pups [maternally reared (MR); n ϭ 22] are used as controls. After 5 d, pups are killed and their organs are harvested. Intestinal villus measurements, protein content, and DNA content are determined. Data are reported as mean Ϯ SEM, compared with appropriate statistical methods, and significance is determined at P Ͻ 0.05. Initial weights and lengths are not different between the two groups, but after 5 d, MR pups weigh more than their AR counterparts (5.0 Ϯ 0.13 versus 4.1 Ϯ 0.14 g, MR versus AR; P Ͻ 0.01). However, the pups' length and the intestinal villus height-to-width ratios, protein, and DNA content are not different between the MR and AR pups. To our knowledge, this is the first report of artificially rearing mouse pups. Development of this technique will permit nutritional manipulation in neonatal mice, a mammalian model wherein the genome is sequenced and transgenic mutants are available. The nutritional status of the newborn and its effects on disease states and intestinal development have long been an area of intense study. Animal model systems are widely used and have proved to be effective for the investigation of a number of illnesses, with the findings extrapolated to the human condition. The development of a rodent in vivo animal model to study neonatal nutrition has been difficult, primarily because during the time that the animal is suckling from the mother and when the intestine is developing rapidly, it is difficult to control the amount and composition of the diet of the experimental neonate.The technique of implanting an intragastric cannula for artificially rearing rat pups is well established (1). This technique allows for the study of a number of neonatal conditions with consistent access to the gastrointestinal tract, allowing for the control and manipulation of both the quantity and the composition of dietary intake in the preweanling rat pups. This model has been used extensively to study a myriad of conditions, including the determination of the nutritional demands for normal growth and development (2). It has been used in studies of intestinal maturation and enzymatic development (3). It has also been used to evaluate the effects of different insults, growth factors, and nutrients on the newborn gut (4,5). The rat pup in a cup model has even been used to study the effects of nutrition (6) and toxin ingestion (7) on early brain development. Although the utility of the rat pup in a cup model has b...

A New Tube Gastrostomy Model in Animal Experiments

“…In conclusion, the main problems in the usage of the orogastric route can be enumerated as time-consuming processes, sedation requirements in many experiment protocols, two personnels for the handling and the manipulation, need for experience, and the mortality due to tracheal intubation [1,2,[7][8][9][10]. Tube ostomies are frequently used but anesthesia requirement, operative mortality, wound infections, damage to the ostomies of the animals between themselves, limitation in the movements of the animals, and high cost are the disadvantages of these routes.…”

The Effect of Artificial Rearing on Gut Microbiota in a Mouse Pup-in-a-Cup Model

“…Artificial rearing of pups is a precondition of nutrition and development study [12], and establishing a mouse pup-in-a-cup model seems possible [1]. However, it has still been difficult to develop a mouse pup-in-a-cup model using newborn mouse pups [22].…”

“…The difficulty in developing a mouse pup-in-a-cup model is implanting an intragastric cannula [1,22], which is the first step in artificial rearing. An oral/percutaneous method is minimally invasive and widely used in rat models [8].…”

“…The rat pupin-a-cup model has been well established for artificial rearing [8] and extensively used to determine the role of nutrients in developmental processes, such as the maturation of the brain and the gastrointestinal tract as well as neonate nutrition-programmed adult metabolic disorder [4,13,20]. The mouse is the primary laboratory animal used in genetic engineering research, so developing a mouse pup-in-a-cup model would benefit study of the interaction between genes and suckling nutrition [1,22]. Although several studies have reported the methods for implanting an intragastric cannula and preparing mouse milk substitute (MMS), it is difficult to place an oral/percutaneous feeding tube in younger mouse pups due to the narrow and vulnerable esophagus of the newborn mouse and the absence of a subtle and tiny commercially available cannula [1,22].…”

“…The mouse is the primary laboratory animal used in genetic engineering research, so developing a mouse pup-in-a-cup model would benefit study of the interaction between genes and suckling nutrition [1,22]. Although several studies have reported the methods for implanting an intragastric cannula and preparing mouse milk substitute (MMS), it is difficult to place an oral/percutaneous feeding tube in younger mouse pups due to the narrow and vulnerable esophagus of the newborn mouse and the absence of a subtle and tiny commercially available cannula [1,22].…”