1
|
Yael A, Fishman R, Matas D, Doniger T, Vortman Y, Koren L. Fetal endocrine axes mRNA expression levels are related to sex and intrauterine position. Biol Sex Differ 2024; 15:61. [PMID: 39103957 DOI: 10.1186/s13293-024-00637-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 07/19/2024] [Indexed: 08/07/2024] Open
Abstract
BACKGROUND The hypothalamic-pituitary-adrenal (HPA) and -gonadal (HPG) axes are two major pathways that connect the neural and endocrine systems in vertebrates. Factors such as prenatal stress and maternal exposure to exogenous steroids have been shown to affect these pathways during fetal development. Another less studied factor is the transfer of hormones across fetuses in multifetal pregnancies. This form of transfer has been shown to influence the morphology, anatomy, physiology, and behavior of the offspring in litter-bearing mammals, an influence termed the intrauterine position (IUP) effect. In this study, we sought to delineate how the IUP effects HPA and HPG brain receptors, peptides, and enzymes (hereafter components) in utero and how these influences may differ between males and females. METHODS We utilized the unconventional model of culled free-ranging nutria (Myocastor coypus), with its large natural variation. We collected brain tissues from nutria fetuses and quantified the expression of key HPA and HPG components in three brain regions: prefrontal cortex, hypothalamus, and striatum. RESULTS We found an interaction between sex and IUP in the mineralocorticoid receptor (MR), gonadotropin-releasing hormone receptor (GNRHR), androgen receptor (AR), and estrogen receptor alpha (ESR1). IUP was significant in both gonadotropin-releasing hormone (GnRH) and its receptor GNRHR, but in different ways. In the hypothalamus, fetuses adjacent to same-sex neighbors had higher expression of GnRH than fetuses neighboring the opposite sex. Conversely, in the cortex, GNRHR exhibited the inverse pattern, and fetuses that were neighboring the opposite sex had higher expression levels than those neighboring the same sex. Regardless of IUP, in most components that showed significant sex differences, female fetuses had higher mRNA expression levels than male fetuses. We also found that HPA and HPG components were highly related in the early stages of gestation, and that there was an interaction between sex and developmental stage. In the early stages of pregnancy, female component expression levels were more correlated than males', but in the last trimester of pregnancy, male components were more related to each other than female's. CONCLUSIONS This study suggests that there are sexually different mechanisms to regulate the HPA and HPG axes during fetal development. Higher mRNA expression levels of endocrine axes components may be a mechanism to help females cope with prolonged androgen exposure over a long gestational period. Additionally, these findings suggest different coordination requirements of male and female endocrine axes during stages of fetal development.
Collapse
Affiliation(s)
- Ariel Yael
- The Faculty of Life Sciences, Bar-Ilan University, 5290002, Ramat Gan, Israel
| | - Ruth Fishman
- The Faculty of Life Sciences, Bar-Ilan University, 5290002, Ramat Gan, Israel
- Department of Brain Sciences, Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Devorah Matas
- The Faculty of Life Sciences, Bar-Ilan University, 5290002, Ramat Gan, Israel
| | - Tirza Doniger
- The Faculty of Life Sciences, Bar-Ilan University, 5290002, Ramat Gan, Israel
| | - Yoni Vortman
- Department of Animal Sciences, Hula Research Center, Tel Hai Academic College, Upper Galilee, 1220800, Qiryat Shemona, Israel
| | - Lee Koren
- The Faculty of Life Sciences, Bar-Ilan University, 5290002, Ramat Gan, Israel.
| |
Collapse
|
2
|
Sarid S, Naor H, Asfur M, Khokhlova IS, Krasnov BR, Kotler BP, Degen AA, Kam M, Koren L. Free-living gerbils with higher testosterone take fewer risks. Physiol Behav 2023; 269:114277. [PMID: 37352905 DOI: 10.1016/j.physbeh.2023.114277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/18/2023] [Accepted: 06/20/2023] [Indexed: 06/25/2023]
Abstract
Among the physiological differences between the sexes are circulating androgen levels. Testosterone (T) is an androgen that has been linked to aggression and risk-taking in male vertebrates, so that males with higher T are generally more aggressive and take more risks. In females, T is not often measured, and its relationship with behaviour has been less studied. The costs of elevated T are assumed to be higher for reproductive females, while the benefits higher for males. Here, we tested the association between endogenous T and risk-taking behaviours in both males and females under well-studied experimental settings in free-living Baluchistan gerbils (Gerbillus nanus; Gn). In addition, we experimentally elevated Gn T levels using implants and measured risk-taking behaviour. Surprisingly, we found that there were no differences in the association between T and risk-taking behaviours between males and females, and that in both sexes, Gn with higher T levels took fewer risks. We also found that Gn spent equal time foraging between risky (open habitat) and safe (under a bush) experimental food patches. We expected Gn, which are nocturnal, to take fewer risks during full moon nights, but found that Gn were more active during moon lit nights than during dark (new moon) nights. This study demonstrates that T has many functions, and that its effects are complex and often unpredictable. It also shows that hypotheses regarding the propensity to take risks under specific coverage and light regimes are not universal, and likely include variables such as species, environment, context, and predator-specific behavioural strategies.
Collapse
Affiliation(s)
- Shani Sarid
- Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel
| | - Hen Naor
- Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel
| | - Mustafa Asfur
- Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel
| | - Irina S Khokhlova
- Desert Animal Adaptations and Husbandry, Wyler Department of Dryland Agriculture, French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Boris R Krasnov
- Mitrani Department of Desert Ecology, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Burt P Kotler
- Mitrani Department of Desert Ecology, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - A Allan Degen
- Desert Animal Adaptations and Husbandry, Wyler Department of Dryland Agriculture, French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Michael Kam
- Desert Animal Adaptations and Husbandry, Wyler Department of Dryland Agriculture, French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Lee Koren
- Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel.
| |
Collapse
|
3
|
Wallace KME, Hart DW, Hagenah N, Ganswindt A, Bennett NC. A comprehensive profile of reproductive hormones in eusocial Damaraland mole-rats (Fukomys damarensis). Gen Comp Endocrinol 2023; 333:114194. [PMID: 36538992 DOI: 10.1016/j.ygcen.2022.114194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 11/03/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
In species where sociality and group cohesion are primarily determined by the maintenance of a reproductive division of labour and cooperative behaviours, the eusocial Damaraland mole-rat (Fukomys damarensis) presents a model which provides behavioural and endocrine distinctions between sex (males and females) and reproductive class (breeders and non-breeders). Although previous studies have demonstrated the endocrine aspects of reproductive suppression and behaviour in Damaraland mole-rats, they have focused on one hormone separately and on different conspecifics and samples across time. Unfortunately, this could introduce extrinsic biases when using these studies to compile complete hormonal profiles for comparisons. This study, therefore, set out to obtain a profile of the reproductive hormones from breeding and non-breeding male and female Damaraland mole-rats at a single point in time, from which circulating plasma prolactin and urinary progesterone, testosterone, and cortisol were measured. As expected, plasma prolactin and urinary cortisol did not differ between the breeders and non-breeders. However, breeders (both male and female) possessed increased urinary testosterone and progesterone concentrations compared to their non-breeding counterparts. These results, in conjunction with the variation in the expression of the respective hormonal receptors within the brains of breeders and non-breeders suggest that elevated testosterone and progesterone in breeders establish a neural dominance phenotype, which ultimately aids in controlling breeding activities. This study has emphasised the need for holistic, comprehensive profiling of reproductive endocrine systems.
Collapse
Affiliation(s)
- Kyra M E Wallace
- Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa.
| | - Daniel W Hart
- Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
| | - Nicole Hagenah
- Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa; Mammal Research Institute, University of Pretoria, Pretoria 0002, South Africa
| | - Andre Ganswindt
- Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa; Mammal Research Institute, University of Pretoria, Pretoria 0002, South Africa
| | - Nigel C Bennett
- Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa; Mammal Research Institute, University of Pretoria, Pretoria 0002, South Africa
| |
Collapse
|
4
|
Boersma J, McQueen A, Peters A, Welklin JF, Khalil S, Quispe R, Goymann W, Schwabl H. Unexpected long-term retention of subcutaneous beeswax implants and additional notes on dose and composition from four testosterone implant studies. Gen Comp Endocrinol 2023; 330:114124. [PMID: 36243058 DOI: 10.1016/j.ygcen.2022.114124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/20/2022] [Accepted: 08/31/2022] [Indexed: 11/17/2022]
Abstract
Experimental manipulations of testosterone have advanced our understanding of the hormonal control of traits across vertebrates. Implants are commonly used to supplement testosterone and other hormones to organisms, as they can be readily scaled to produce desired hormone levels in circulation. Concerns about pharmacological (i.e. unnatural) doses of traditional silastic implants led to innovation in implant methods, with time-release pellets and beeswax implants proposed as solutions. A study comparing silastic, time-release pellets, and beeswax implants found the latter to be most effective in delivering a physiologically relevant dose. One proposed advantage to subcutaneous beeswax implants is that they are expected to degrade within the body, thus removing the obligation to recapture implanted individuals in the field. However, few studies have reported on dosage and no published literature has examined the assumption that beeswax implants readily degrade as expected. Here we present time-release androgen data in relation to implants containing varying levels of testosterone from four separate implant studies. In addition, we report long-term persistence of subcutaneous implants, including two cases of implants being retained for > 2 years. Finally, we offer recommendations on the composition and implementation of beeswax implants to aid the pursuit of minimally invasive and physiologically relevant manipulations of circulating hormones.
Collapse
Affiliation(s)
- Jordan Boersma
- School of Biological Sciences, Washington State University, Pullman, WA, USA; Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA.
| | - Alexandra McQueen
- School of Biological Sciences, Monash University, Clayton, VIC, Australia; Centre for Integrative Ecology, Deakin University, Burwood, VIC, Australia
| | - Anne Peters
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | | | - Sarah Khalil
- Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA
| | - René Quispe
- Abteilung für Verhaltensneurobiologie, Max-Planck-Institut für Ornithologie, Seewiesen, Germany; Departmento de Ciencias Biológicas Animales, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, CL, USA
| | - Wolfgang Goymann
- Abteilung für Verhaltensneurobiologie, Max-Planck-Institut für Ornithologie, Seewiesen, Germany
| | - Hubert Schwabl
- School of Biological Sciences, Washington State University, Pullman, WA, USA; Abteilung für Verhaltensneurobiologie, Max-Planck-Institut für Ornithologie, Seewiesen, Germany
| |
Collapse
|