Integrating the dimension of sex and gender into basic life sciences research: problems and solutions

1. Integrating the dimension of sex and gender into basic life sciences research:problems and solutions Dr Anita Holdcroft MB ChB MD FRCA Reader in Anaesthesia and Honorary Consultant Anaesthetist Gender Basic January 2007

2. Sex…… the “classification of living things, generally as male or female according to their reproductive organs and functions assigned by chromosome complement” ‘Exploring the biological contributions to human health. Does sex matter?’ Wizemann and Pardue IO M, National Academy Press 2001 p17. Gender Basic January 2007

3. Gender……….. “a person’s self-representation as male or female, or how that person is responded to by social institutions on the basis of the individual’s gender presentation” ‘Exploring the biological contributions to human health. Does sex matter?’ Wizemann and Pardue IO M, National Academy Press 2001 p17. Gender Basic January 2007

4. Gender ……… • Use of language • Masculinity • Femininity • Or a continuum Male Female Gender Basic January 2007

5. Sex Genetic Molecular Cellular Physiological Gender Psychological Environmental Social Cultural Sex and Gender Gender Basic January 2007

6. Sex Genetic Molecular Cellular Physiological Gender Psychological Environmental Social Cultural Sex and Gender interactions Gender Basic January 2007

7. Example of sex/gender interaction Irritable bowel syndrome: symptoms • Females > Males (Corney & Stanton 1990, Talley 1991, Taub et al 1995, Heitkemper et al 2003) • Longer episodes of pain • Constipation • Bloating • Why? • Physiology (Heitkemper et al 2003) • Factors exacerbating symptoms • Greater female:male use of OTC medications (Isacson & Bingefors 2002) Gender Basic January 2007

8. Developing guidelines in Sex and Gender research • Endocrinology Becker et al 2005;146:1650 “Strategies and methods for research on sex differences in brain and behavior” Supported by the Society for Women’s Health Research (USA) • IASP SIG Sex, gender and pain (International Association for the Study of Pain, Special Interest Group) 3 groups: basic science, translational (human experimental), clinical (human disease) in progress from September 2006 Gender Basic January 2007

9. Experimental questions: No Is there a sex difference? ‘Yes’-Test for sex hormones at time of testing ‘No’ -Test for developmental effects of sex hormones ‘No’- Test for sex chromosome effects Was the sex difference lost on the way? Strategies and methods for research on sex differences in brain and behavior’ Becker 2005 Gender Basic January 2007

10. Experimental questions: Consider forces that cancel each other out No Is there a sex difference? ‘Yes’-Test for sex hormones at time of testing ‘No’ -Test for developmental effects of sex hormones ‘No’- Test for sex chromosome effects Is this a gender effect? Was the sex difference lost on the way? Does this change with pathophysiology? Gender Basic January 2007

11. Is there a sex or gender difference? Examples of factors influencing results: • Age • Physical composition/size • Environment/time of day/experimenter • Methodology (site, stimulus, analysis) • Reproductive history (cycle, parity) Gender Basic January 2007

12. Age ‘Qualitative sex differences in kappa-opioid analgesia in mice are dependent on age.’ Sternberg WF, Ritchie J, Mogil JS. (Neurosci Lett. 2004) Response to -opioid analgesia and NMDA antagonist blocked in • male rodents • elderly females (partial) not blocked in • hormonally intact females Gender Basic January 2007

13. Confounding factors for age: • Definition of aging:variable e.g. 9 – 30m • Time of gonadectomy • Perinatal: organisation of neural pathways • Adult: activation • Analysis: young versus old; continuous • Changes in opioid mechanisms with age • Opioid receptor binding, affinity and concentrations decreased in regional and whole brain assays • Levels of beta-endorphin, leu-enkephalin, met-enkephalin decreased (Organismic variables and pain inhibition: roles of gender and aging. Bodnar RJ, Romero M-T, Kramer E. Brain Res Bull, 1988) Gender Basic January 2007

14. Is there a sex or gender difference? Examples of factors influencing results: • Age • Physical composition/size • Environment/time of day/experimenter • Methodology (site, stimulus, analysis) • Reproductive history (cycle, parity) Gender Basic January 2007

15. Body composition water fat solids - proteins men women Gender Basic January 2007

16. Physical factors – application • 1 acid glycoprotein • reduced by oestrogen • albumin • reduced in pregnancy men women Gender Basic January 2007

17. Is there a sex or gender difference? Examples of factors influencing results: • Age • Physicalcomposition/size • Environment/time of day/experimenter • Methodology (site, stimulus, analysis) • Reproductive history (cycle, parity) Gender Basic January 2007

18. Visceral stimulation and vasopressin (AVP) release (Holdcroft et al Br J Anaesth 2000) EMG Inhalation anaesthetic Inflate colorectal balloon • Males (n = 5) and females (n = 22) • AVP measured pre and post stimulation • Balloon pressure measured at the time when the visceromotor response was obtained (EMG) Gender Basic January 2007

19. Visceromotor response (Holdcroft et al Br J Anaesth 2000) Gender Basic January 2007

20. inhalation Visceral stimulation and AVP release balloon • Sex differences • Post stimulation in AVP (P=0.002) • Balloon pressure (P=0.002) • Hypothalamopituitary axis is more reactive-females>males (Holdcroft et al Br J Anaesth 2000) Gender Basic January 2007

21. Is there a sex or gender difference? Examples of factors influencing results: • Age • Physical composition/size • Environment/time of day • Methodology (site, stimulus, analysis) • Reproductive history (cycle, parity) Gender Basic January 2007

22. Parity and breast pain Pain scores parity Holdcroft, A., Snidvongs, S., Cason, A., Dore, C., Berkley, K.J. “Pain and uterine contractions during breast-feeding in the immediate post-partum period increased with parity.” Pain 104, (2003), 589-596. Gender Basic January 2007

23. NGF increases in painful breast tissues No pain Breast pain Gopinath, Wan, Holdcroft et al 2005 Gender Basic January 2007

24. Is there a sex difference? Examples of how sex differences are lost - • Select random females • Small groups • Housing: females living together synchronise cycles • Variability among animals/humans Gender Basic January 2007

25. ACTH Angiotensin II αMSH AVP Bradykinin CCK CorticotropinRH Galanin GABA Glucagon GH GHRH Insulin LH Motilin NGF Prolactin Somatostatin Thyrotropin Thyrotropin RH VIP VR1 AVP Bradykinin Bombesin Cannabinoids CCK Choline acetyltransferase Dopamine Enkephalins Galanin GABA Glutamate Insulin-like growth factor NMDA Neurokinin A NGF NO Oxytocin Preproenkephalin Serotinin (5-HT) Substance P VR1/TRPV1/Vanilloid receptor Nociceptor neurochemicals/receptors influenced by hormone manipulations(Holdcroft & Berkley 2005) Animals Humans (from Medline search using agent and ‘hormone’ ‘reproductive cycle’ etc) Gender Basic January 2007

26. Morphine analgesia and sex differences depend on strain of mice M = ; F = F>M M>F M>F M>F Kest, Wilson and Mogil 1999 Gender Basic January 2007

27. Small gender differences become BIG Coronary artery disease (Visceral pain) • Symptoms and co-morbidity differ • Females: nausea, SOB, throat, neck, jaw and back pain more common (Philoptt et al 2001, Kyker & Limacher 2002) • Females: more diabetes and older (Weintraub et al 1993) • Diagnosis and treatment ‘a woman has to masquerade as a man in order to receive the same treatment’ = Yentl syndrome (Swahn 1998) • Females had twice the morbidity of males for CABG surgery (Woods etl al 2003) Gender Basic January 2007

28. Study design • Animal models relate to human conditions • Comorbidity (in human disease) • Gender effects • Reduce variation • Physical factors • Biological rhythms • Other factors • Study size and analysis • Meta-analysis (comparison, evidence basis) • Selection of measurement time/state • Interactions at molecular level • Peer review Gender Basic January 2007

29. Heat stimuli and cerebral activation PET = positron emission tomography H215O regional blood flow Heat stimulus Gender Basic January 2007

30. Gender differences to somatic pain Paulson et al Pain 1998 40oC Innocuous More response in females P = 0.05 50oC Noxious Gender Basic January 2007

31. Sex differences in the perception of noxious stimuli: threshold(Riley 1998) * mean males – mean females/pooled SD Gender Basic January 2007

32. Thermal stimuli and sites Heat stimulus ‘Forced choice method’ Gender Basic January 2007

33. Thermal stimuli:males and females Arm Abdomen Back Forced choice method Patel A, Keogh E, Stephens D, Holdcroft A. Sex differences in pain: a new methodological approach. Br J Anaesth 2005;94:402P. Gender Basic January 2007

34. Thermal stimuli - hormones Significant difference between F&M vs OCP (P=0.001, Wald test) Gender Basic January 2007

35. Study design • Animal models relate to human conditions • Comorbidity (in human disease) • Gender effects • Reduce variation • Physical factors • Biological rhythms • Other factors • Study size and analysis • Meta-analysis (comparison, evidence basis) • Selection of measurement time/state • Interactions at molecular level • Peer review Gender Basic January 2007

36. Thanks to…. Mary Forsling Preethi Gopinath Elaine Wan Praveen Anand Sue Sapsed-Byrne Daqin Ma MK Chakrabarti Karen Berkley Saz Snidvongs Caroline Doré Angie Cason Nadeem Sayeed Paul Facer Ed Keogh Akta Patel Katherine Mc Ginn David Stephens Gender Basic January 2007