The NIH has moved the requirements in rodent research recently. Previously, using only male rodents (bucks) was considered just fine. After some really alarming studies out of McGill [0], much of the field has changed. Now, you must garner a waiver to only use one sex vs. the other in rodent studies. The effects of this change remain to be seen, but are generally thought of as positive.
Some context is needed though. The estrous cycle of dams is fairly complicated[1]. Controlling variables in hormones, hydration, etc. is much easier in bucks. Since the experiments are easier to control for, you need less rodents and therefore you need less funding for rodent care and housing, and you need to sacrifice less rodents to do the experiment (generally). Hence why they have been the 'preferred' rodent sex historically, among many other reasons.
Additionally, rodents are some of the 'first' level in vivo models, but are far from the last in the long line of research that is human applicable. It is very common that research done in rodents will not translate to other mainstay research vertebrates like dogs and monkeys, let alone into humans. The differences in the sexes are vastly outweighed by the differences in species.
Generally, yes, it is good that we are now defaulting to having to use both sexes of rodents. However, costs and sacrifices per experiment have risen as a result. All things have trade-offs in our world.
Some context is needed though. The estrous cycle of dams is fairly complicated[1]. Controlling variables in hormones, hydration, etc. is much easier in bucks. Since the experiments are easier to control for, you need less rodents and therefore you need less funding for rodent care and housing, and you need to sacrifice less rodents to do the experiment (generally). Hence why they have been the 'preferred' rodent sex historically, among many other reasons.
Additionally, rodents are some of the 'first' level in vivo models, but are far from the last in the long line of research that is human applicable. It is very common that research done in rodents will not translate to other mainstay research vertebrates like dogs and monkeys, let alone into humans. The differences in the sexes are vastly outweighed by the differences in species.
Generally, yes, it is good that we are now defaulting to having to use both sexes of rodents. However, costs and sacrifices per experiment have risen as a result. All things have trade-offs in our world.
[0] https://www.google.com/search?q=mcgill+pain+mice+research+ma...
[1] https://embryology.med.unsw.edu.au/embryology/index.php/Estr...