Impact of transgenic procedures on behavioral and physiological responses in postweaning mice

This study evaluates the effects of biotechnological procedures involved in the process of microinjection-induced transgenesis in the mouse by compari ng four groups of C57BL/6 mice that differ in their transgenic background ( transgenics after integration of a functional corticotropin-releasing facto r (CRF) gene construct, transgenics after integration of a nonfunctional CR F gene construct, nontransgenies after transgenic procedures, and controls) . These four groups have been tested in various behavioral paradigms. Moreo ver, the development in growth, morphological characteristics, and clinical appearance of the animals have been recorded from 4 till 30 weeks of age. Differences in behavior, weight gain, and morphology were found between Gro up I ((transgenic CRF animals) and Group 4 (control animals). For Group 2 ( animals with a noncoding construct) and Group 3 (nontransgenic animals afte r transgenic procedures), no significant differences from control animals w ere found. This indicates that, under the present conditions, the biotechno logical procedures related to transgenesis (microinjection, in vitro cultur e, and embryo transfer) have no significant effect on the normal developmen t of the mice in the postweaning period. These results substantiate previou s findings on these animals, obtained by screening them in the preweaning p eriod (Days 0-21). However, before general conclusions as to what extent th e technique of transgenesis affects the welfare of the animals can be drawn , more and different transgenic lines should be studied in this or a simila r way. (C) 2001 Elsevier Science Inc. All rights reserved.