PREGNANT’ MALE RAT Other — for Example from an Elderly Mouse to a Youthful One, to Study the Process of Ageing

technique for connecting animals to study the effects of infusing blood from one to the ‘PREGNANT’ MALE RAT other — for example from an elderly mouse to a youthful one, to study the process of ageing. STUDY KINDLES ETHICAL Six weeks after the castration and surgery, testosterone levels in the male rats had DEBATE IN CHINA declined — but their oestrogen and progester- one levels mirrored those in the female rats. Researchers question the value of the experiment — Eight weeks after surgery, the researchers transplanted a uterus into each male rat, which involved sewing together male and female rats. followed by embryos into both the male and female after another eight weeks. Three weeks By Smriti Mallapaty into the embryos’ development, and near the end of a normal rat pregnancy, the researchers n experiment to impregnate male rats delivered the pups by caesarean section. stitched to female rats, by research- Out of 842 embryos introduced into 46 con- ers at the Naval Medical University in joined pairs of rats, one-third of those in the Shanghai, has stirred debate in China female rats and one-tenth of those in the about the ethics of the work. male rats developed into viable fetuses. Only AResearchers say the experiment was highly 10 pups gestated in the male rats survived to contrived and unnecessarily distressing to the adulthood — some 4% of the 280 embryos animals, and that it offers few insights into the implanted in the male rats. The adult rats possibility of pregnancy in people assigned were subsequently separated, and all the males male at birth — if anything, the poor success survived for another three months, until they rate suggests that such a goal is a long way off. were euthanized. But other scientists say the rat model could The authors say the findings point to the eventually be used to tease apart what might importance of the pregnant female’s blood be required to maintain pregnancy in peo- supply, because the embryos did not mature ple of any sex who wish to bear children. The in males that were attached to females with-

APA PICTUREDESK GMBH/SHUTTERSTOCK APA study was detailed in a bioRxiv preprint posted out developing fetuses. The importance of the online on 10 June (R. Zhang and Y. Liu Preprint Laboratory rats. A study used conjoined blood supply and the low rate of births suggest at bioRxiv https://doi.org/gnnz; 2021). pairs: females attached to castrated males. that “male pregnancy in humans is not feasible “The experiment has no social value and at this stage”, Zhang wrote on PubPeer, adding: just wasted the money taken from taxpayers,” rather than a serious and responsible aca- “If our result is correct, this is almost a death says Qiu Renzong, a bioethicist at the Chinese demic endeavour”, says Zhang. sentence for human male pregnancy.” Academy of Social Science in Beijing. It is not clear whether the experiment was The paper was recently among the top-trend- approved by an independent ethics committee Limited scientific insights ing subjects on the Chinese social-media — a requirement for all publicly funded exper- But other researchers say the importance of a platform Weibo. Some researchers in China iments involving laboratory animals — says mother’s endocrine system is already known. fear that reckless biological experimentation Zhang Xinqing, a bioethicist at Peking Union The study offers limited insights, says Chris could blemish the country’s reputation. Medical College in Beijing. Zhang adds that if O’Neill, a retired researcher formerly based at it had been up to him, he would not have voted the University of Sydney in Australia, who has Ethical issues to approve this experiment. studied the biology of pregnancy. The model Chinese scientists are concerned that con- The authors declined to comment on ques- is effectively an ex vivo model of female preg- troversial research, such as this study, could tions about the research posed by Nature. Their nancy, he adds: a female uterus and blood reinforce an “already tainted image of Chinese manuscript states that the work could have “a supply in a castrated male. “It tells us that at science”, says Joy Zhang, a sociologist at the profound impact on reproductive biology”, least within the castrated male, there is no fun- University of Kent in Canterbury, UK, who has but did not clarify why. In a public statement damental hostility of the male environment to conducted research in China over many years. on PubPeer, a website for post-publication carrying a fetus,” he says. The study is one of several in recent years that peer review, one of the authors, Zhang Rongjia, The intrusive surgical intervention also Chinese researchers feel have presented a said the work was performed “for our personal doesn’t lend itself to being applied to people, “distorted image” of what they think China’s interests and curiosity”, and that they made says Catherine Mills, a bioethicist at Monash research culture should be, she says. efforts to reduce the number of animals used University in Melbourne, Australia. “It is quite In one high-profile case from 2018, a Chinese and to minimize their pain. a long way from any real implication for human researcher announced the birth of the first Pregnancy in males is extremely rare in research,” she says. “In a sense, it is not an ani- genome-edited babies, which was widely nature, and is observed only in a group of mal model; it is just an animal experiment.” criticized as unethical. The incident spurred fish that includes seahorses and pipefishes. Zhang Rongjia declined to comment on the efforts to strengthen ethical governance, To study the possibility of achieving it in criticisms of the value of the work, stating in including the formation of a committee to mammals, the Chinese researchers sewed an e-mail to Nature that the authors “prefer advise the government on research ethics. the elbows, knees and skins of pairs of rats to respond to external criticism by formally There is a worry “that the underlying trend together, each consisting of a castrated male publishing academic papers”. of ‘science through PR’ — the mentality that and a female, to join their blood supply. This O’Neill says the study might provide a new experiments with outlandish objectives are conjoined model, known as a parabiont, allows experimental model for identifying nutrients a shortcut to public attention — would turn the animals to share blood. or hormones in maternal blood that are crucial science into a form of entertainment business Parabiosis is an established surgical for a successful pregnancy.