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Animals Have a Sex, and so Should Titles and
Methods Sections of Articles in Endocrinology
Jeffrey D. Blaustein
Neuroscience and Behavior Program, University of Massachusetts, Amherst, Massachusetts 01003
eginning with papers submitted as of July 1, 2012, the
methods sections of manuscripts submitted to Endocrinology must indicate the sex of animals used, or in the
case of primary cells or cultures, the sex of animal from
which they were derived. Although not required, authors
are also encouraged to identify the sex of cell lines used in
cell cultures. If the experiment is of a mixed-sex design, the
numbers of males and females should be indicated in the
methods. If only one sex of animal was used in an experiment, the title should indicate the sex of animal used.
Recently, the Institute of Medicine of the National
Academies of Science recently hosted a workshop entitled
“Sex-Specific Reporting of Scientific Research” sponsored
by the Office of Research on Women’s Health of the National Institutes of Health (1). The opinion of many of the
discussants was that, considering the differences between
males and females for so many biological factors, the sex
of animals used in experiments should be identified in
journal articles. Similarly, most participants agreed that
when only one sex was studied, then that should be clearly
indicated in the methods section of the paper.
This issue of Endocrinology includes three invited minireviews that persuasively make the case that the sex of
animals is a critical variable in all of biology (2– 4). These
three minireviews note the importance of knowing the sex
of the animals used in studies ranging from immune cells
to human brain function. Although the study of only one
sex is acceptable in some cases, such as reproduction, the
study of only one sex with an expectation of generalizing
to both sexes is not. With many variables, the response of
males and females may differ as much as in studies in
which different strains or species of animal are used.
Therefore, we believe it is of utmost importance to prominently identify the sex of animals used in biological re-
B
search. Although experiments will continue to be performed on only one sex, it is important to call attention of
our authors and readers to this issue.
In addition to the Institute of Medicine monograph on
sex-specific reporting of scientific research and the minireviews in this issue of Endocrinology, many other publications recently have made the case that sex cannot be
ignored in biological research (5, 6). Beery and Zucker (5)
conducted an extensive analysis of sex of animals used in
publications in a variety of disciplines. In some disciplines,
when sex of animal is specified in the methods sections of
scientific reports, the subjects tend to be males, perhaps
because researchers do not want to deal with the so-called
complication of the estrous or menstrual cycle of females.
It is interesting that 20 yr ago, Karen Berkley (7) pointed
out that in many research papers, in that case, in Neuroscience, the sex of animals used was not specified.
We expect that our new policy will evolve as awareness
of the need to consider both sexes in endocrine research
increases, and we expect that just as was the case in human
research, the federal agencies will get involved in the conversation. In time, inclusion of both sexes in animal research may be required, as it is now with human subject
studies (http://orwh.od.nih.gov/inclusion.html). Eventually, sex-specific information may be required in studies
with a mixed-sex design. However, for now, our goal is to
raise awareness of the fact that, just as species, strain, age,
and other variables must be considered in reporting of
biological research, so should sex of animals.
Although some recent papers have provided blueprints
of how to consider both sexes in biological research (8, 9),
the goal of the new policy of this journal is simply to ensure
that the sex of animals is reported and mentioned in the
title if only one sex was used. The goal is not to change the
ISSN Print 0013-7227 ISSN Online 1945-7170
Printed in U.S.A.
Copyright © 2012 by The Endocrine Society
doi: 10.1210/en.2012-1365 Received April 3, 2012. Accepted April 10, 2012.
For articles see pages 2541, 2544, 2551
Endocrinology, June 2012, 153(6):2539 –2540
endo.endojournals.org
2539
2540
Blaustein
News & Views
direction of endocrine research, so that sex of animals is
considered in all experiments. However, in the opinion of
this Editor-in-Chief, sex of animals studied is a particularly important factor in all of biological research, and
such consideration would be a superb side effect of this
change.
Endocrinology is not the first journal to draw attention
to the importance of sex or gender in biological research.
With this change, we will join the other leaders, as well as
the National Institutes of Health and the Institute of Medicine of the National Academies of Science, in this effort to
draw attention to the importance of consideration of the
sex of animals used in biological research.
Acknowledgments
I thank Art Arnold and Margaret McCarthy for helpful discussions in developing this change in policy. I thank Renee Pessin for
helpful comments on the manuscript.
Address all correspondence and requests for reprints to: Professor Jeffrey D. Blaustein, Ph.D., University of Massachusetts
Neuroscience and Behavior Program, Tobin Hall Room 441 135
Endocrinology, June 2012, 153(6):2539 –2540
Hicks Way, University of Massachusetts, Amherst, Massachusetts 01003-9271. E-mail: [email protected].
Disclosure Summary: The author has nothing to disclose.
References
1. Wizeman TM 2012 Sex-specific reporting of scientific research: a
workshop summary. Washington, DC: National Academies Press
2. Klein SL 2012 Immune cells have sex and so should journal articles.
Endocrinology 153:2544 –2550
3. Arnold AP, Lusis AJ 2012 Understanding the sexome: measuring
and reporting sex differences in gene systems. Endocrinology 153:
2551–2555
4. Cahill L 2012 A half-truth is a whole lie: on the necessity of investigating sex influences on the brain. Endocrinology 153:2541–2543
5. Beery AK, Zucker I 2011 Sex bias in neuroscience and biomedical
research. Neurosci Biobehav Rev 35:565–572
6. Zucker I, Beery AK 2010 Males still dominate animal studies. Nature 465:690
7. Berkley KJ 1992 Vive la difference. Trends Neurosci 15:331–332
8. Becker JB, Arnold AP, Berkley KJ, Blaustein JD, Eckel LA, Hampson E, Herman JP, Marts S, Sadee W, Steiner M, Taylor J, Young E
2005 Strategies and methods for research on sex differences in brain
and behavior. Endocrinology 146:1650 –1673
9. McCarthy MM, Arnold AP, Ball GF, Blaustein JD, De Vries GJ 2012
Sex differences in the brain: the not so inconvenient truth. J Neurosci
32:2241–2247