scholarly journals Immune activation suppresses plasma testosterone level: a meta-analysis

2008 ◽  
Vol 4 (6) ◽  
pp. 741-744 ◽  
Author(s):  
Jelle J Boonekamp ◽  
Albert H.F Ros ◽  
Simon Verhulst
Keyword(s):  
Immune Function ◽  
Immune Activation ◽  
Meta Analysis ◽  
Mechanistic Explanation ◽  
Suppressive Effect ◽  
Plasma Testosterone ◽  
Sexual Signals ◽  
Trade Off ◽  
Testosterone Levels ◽  
Handicap Hypothesis

Females often select mates on the basis of sexual signals, which can be reliable indicators of male quality when the costliness of these signals prevents cheating. The immunocompetence handicap hypothesis (ICHH) provides a mechanistic explanation of these costs, by proposing a trade-off between immune function and sexual displays. This trade-off arises because testosterone enhances sexual signals, but suppresses immune function. Many studies have investigated the ICHH by administrating testosterone, and a recent meta-analysis found little evidence that testosterone suppressed immune function. However, another component of the ICHH, which has received less empirical interest, suggests that there may also be an interaction in the other direction, with immune activation suppressing testosterone levels. We present a meta-analysis to test for this effect. Overall, there was a strong suppressive effect of experimental immune activation on testosterone levels ( r =−0.52), regardless of whether live pathogens or non-pathogenic antigens were used to challenge the immune system. The latter is important because it shows that immune activation per se suppresses testosterone levels. Thus, a trade-off between immunocompetence and sexual displays may primarily be generated by the effect of immune activation on testosterone, rather than the opposite effect that has received most attention.

scholarly journals Structural colours reflect individual quality: a meta-analysis

2020 ◽  
Vol 16 (4) ◽  
pp. 20200001
Author(s):  
Thomas E. White
Keyword(s):  
Immune Function ◽  
Body Condition ◽  
Meta Analysis ◽  
Visual Ecology ◽  
Individual Quality ◽  
Sexual Signals ◽  
Parasite Resistance ◽  
Structural Coloration ◽  
Exchange Of Information ◽  
The Relationship

Colourful ornaments often communicate salient information to mates, and theory predicts covariance between signal expression and individual quality. This has borne out among pigment-based signals, but the potential for ‘honesty’ in structural coloration is unresolved. Here, I synthesized the available evidence to test this prediction via meta-analysis and found that, overall, the expression of structurally coloured sexual signals is positively associated with individual quality. The effects varied by the measure of quality, however, with body condition and immune function reliably encoded across taxa, but not age nor parasite resistance. The relationship was apparent for both the colour and brightness of signals and was slightly stronger for iridescent ornaments. These results suggest diverse pathways to the encoding and exchange of information among structural colours while highlighting outstanding questions as to the development, visual ecology and evolution of this striking adornment.

scholarly journals Structural colours reflect individual quality: a meta-analysis

2020 ◽  
Author(s):  
Thomas E. White
Keyword(s):  
Immune Function ◽  
Body Condition ◽  
Meta Analysis ◽  
Visual Ecology ◽  
Individual Quality ◽  
Sexual Signals ◽  
Parasite Resistance ◽  
Exchange Of Information ◽  
Structural Colouration ◽  
The Relationship

AbstractOrnamental colouration often communicates salient information to mates, and theory predicts covariance between signal expression and individual quality. This has borne out among pigment-based signals, but the potential for ‘honesty’ in structural colouration is unresolved. Here I synthesised the available evidence to test this prediction via meta-analysis and found that, overall, the expression of structurally coloured sexual signals is positively associated with individual quality. The effects varied by measure of quality, however, with body condition and immune function reliably encoded across taxa, but not age nor parasite resistance. The relationship was apparent for both the colour and brightness of signals and was slightly stronger for iridescent ornaments. These results suggest diverse pathways to the encoding and exchange of information among structural colours, while highlighting outstanding questions as to the development, visual ecology, and evolution of this striking adornment.

Testosterone, body size, and sexual signals predict parasite load in Yarrow’s Spiny Lizards (Sceloporus jarrovii)

2014 ◽  
Vol 92 (12) ◽  
pp. 1075-1082 ◽  
Author(s):  
W.D. Halliday ◽  
J.E. Paterson ◽  
L.D. Patterson ◽  
S.J. Cooke ◽  
G. Blouin-Demers
Keyword(s):  
Body Size ◽  
Locomotor Activity ◽  
Alternative Hypothesis ◽  
Parasite Load ◽  
Activity Levels ◽  
Sexual Signals ◽  
Testosterone Levels ◽  
Immunocompetence Handicap Hypothesis ◽  
Handicap Hypothesis ◽  
Fecal Testosterone

Parasite load significantly impacts host health and fitness and may vary substantially among individuals within a population. The immunocompetence handicap hypothesis posits that sexual signals are honest indicators of male quality because they are maintained by testosterone, an immunosuppressant that yields higher parasite loads. Additionally, testosterone may influence parasite load by increasing activity levels. We examined these two hypotheses in a wild population of Yarrow’s Spiny Lizards (Sceloporus jarrovii Cope, 1875) in Arizona. We (i) compared fecal testosterone levels to ectoparasite and haemoparasite loads, (ii) tested if sexual signals (total coloured area, aggression, and head size), locomotor activity, and body size correlated with testosterone levels, and (iii) compared sexual signals, locomotor activity, and body size to parasite load. Ectoparasite loads increased with total coloured area and tended to increase with testosterone, but this latter relationship was only nearly significant. Parasite loads increased with body size. Thus, we found some support for the immunocompetence handicap hypothesis and none for the activity hypothesis. Our results are consistent with an alternative hypothesis that larger individuals have more parasites because they have more surface area and (or) have had longer to accumulate parasites. Future studies should examine the relative contributions of testosterone and glucocorticoids in driving variation in parasite loads.

scholarly journals On sexual dimorphism in immune function

2008 ◽  
Vol 364 (1513) ◽  
pp. 61-69 ◽  
Author(s):  
Charles L Nunn ◽  
Patrik Lindenfors ◽  
E. Rhiannon Pursall ◽  
Jens Rolff
Keyword(s):  
Sexual Dimorphism ◽  
Immune Function ◽  
Life Histories ◽  
Meta Analysis ◽  
Empirical Support ◽  
Insect Immunity ◽  
Sexual Competition ◽  
Cell Counts ◽  
Handicap Hypothesis ◽  
White Blood Cell Counts

Sexual dimorphism in immune function is a common pattern in vertebrates and also in a number of invertebrates. Most often, females are more ‘immunocompetent’ than males. The underlying causes are explained by either the role of immunosuppressive substances, such as testosterone, or by fundamental differences in male and female life histories. Here, we investigate some of the main predictions of the immunocompetence handicap hypothesis (ICHH) in a comparative framework using mammals. We focus specifically on the prediction that measures of sexual competition across species explain the observed patterns of variation in sex-specific immunocompetence within species. Our results are not consistent with the ICHH, but we do find that female mammals tend to have higher white blood cell counts (WBC), with some further associations between cell counts and longevity in females. We also document positive covariance between sexual dimorphism in immunity, as measured by a subset of WBC, and dimorphism in the duration of effective breeding. This is consistent with the application of ‘Bateman's principle’ to immunity, with females maximizing fitness by lengthening lifespan through greater investment in immune defences. Moreover, we present a meta-analysis of insect immunity, as the lack of testosterone in insects provides a means to investigate Bateman's principle for immunity independently of the ICHH. Here, we also find a systematic female bias in the expression of one of the two components of insect immune function that we investigated (phenoloxidase). From these analyses, we conclude that the mechanistic explanations of the ICHH lack empirical support. Instead, fitness-related differences between the sexes are potentially sufficient to explain many natural patterns in immunocompetence.

scholarly journals Immunocompetence handicap hypothesis in tree frog: trade-off between sexual signals and immunity?

2015 ◽  
Vol 26 (4) ◽  
pp. 1138-1146 ◽  
Author(s):  
Julia L. Desprat ◽  
Thierry Lengagne ◽  
Adeline Dumet ◽  
Emmanuel Desouhant ◽  
Nathalie Mondy
Keyword(s):  
Tree Frog ◽  
Sexual Signals ◽  
Trade Off ◽  
Immunocompetence Handicap Hypothesis ◽  
Handicap Hypothesis

scholarly journals Testosterone-mediated trade-offs in the old age: a new approach to the immunocompetence handicap and carotenoid-based sexual signalling

2009 ◽  
Vol 276 (1664) ◽  
pp. 2093-2101 ◽  
Author(s):  
C. Alonso-Alvarez ◽  
Lorenzo Pérez-Rodríguez ◽  
Jesus T. Garcia ◽  
Javier Viñuela
Keyword(s):  
Antioxidant Properties ◽  
Optimal Solution ◽  
Cell Mediated Immunity ◽  
Sexual Signals ◽  
Middle Aged ◽  
New Approach ◽  
Trade Off ◽  
Trade Offs ◽  
Sexual Signalling ◽  
Handicap Hypothesis

The immunocompetence handicap hypothesis proposes that testosterone mediates a trade-off between sexual signalling and immunocompetence in males. Such a trade-off could favour the reliability of sexual signals on the basis that testosterone required for signal expression also promotes immunosuppression. However, the immunosuppressive activity of testosterone has not been convincingly demonstrated. We propose that the optimal solution to the testosterone-mediated trade-off should change with age, explaining ambiguous results in the past. Testosterone and ageing would promote two simultaneous immunosuppressive challenges unaffordable for low-quality males. Oxidative stress, as intimately related to ageing and immunosenescence, could contribute to enhance signal reliability. In this context, traits coloured by carotenoids (yellow–red traits) could play a crucial role due to the immunostimulatory and antioxidant properties of these pigments. Here, old and middle-aged male red-legged partridges were treated with testosterone or manipulated as controls. In the presence of high-testosterone levels, middle-aged males increased both circulating carotenoid levels and colour expression, whereas their cell-mediated immunity was not significantly altered. However, in old males, neither circulating carotenoids nor sexual signalling increased when treated with testosterone, but immunosuppression was detected. The link between testosterone and carotenoids could favour the reliability of sexual signals throughout the life.

Trade‐off between growth and immune function: a meta‐analysis of selection experiments

2010 ◽  
Vol 25 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Peter J. van der Most ◽  
Berber de Jong ◽  
Henk K. Parmentier ◽  
Simon Verhulst
Keyword(s):  
Immune Function ◽  
Meta Analysis ◽  
Trade Off ◽  
Selection Experiments

INFLUENCE OF METYRAPONE ON PLASMA CONCENTRATIONS OF TESTOSTERONE AND ANDROSTENEDIONE IN MAN

1971 ◽  
Vol 68 (3) ◽  
pp. 576-584 ◽  
Author(s):  
K. O. Nilsson ◽  
B. Hökfelt
Keyword(s):  
Body Weight ◽  
Male Patient ◽  
Gradual Increase ◽  
Plasma Concentrations ◽  
Plasma Testosterone ◽  
Testosterone Levels ◽  
Basal Plasma ◽  
Normal Males ◽  
A Minor ◽  
Secondary Hypogonadism

ABSTRACT Metyrapone was administered either orally, 750 mg every four h, in a total of six doses, or intravenously 30 mg per kg body weight as a four h infusion. In three males with normal endocrine functions, metyrapone given orally or intravenously induced a fall in plasma testosterone and an elevation of androstenedione within 2–8 h. When metyrapone was administered to a patient given dexamethasone to suppress endogenous ACTH production, the androstenedione levels did not alter whereas the testosterone levels showed a slight, transient decrease. In two normal females metyrapone administration was followed by a marked increase in plasma androstenedione whereas testosterone showed only a minor, gradual increase. In one male patient with Addison's disease the basal plasma testosterone was normal whereas the level of androstenedione was low. Following metyrapone intravenously, there was a slight suppression of plasma testosterone but no change in the androstenedione concentration. In one patient with primary hypogonadism, two with secondary hypogonadism and two with Klinefelter's syndrome the plasma testosterone was low under basal conditions and did not change following metyrapone. Basal plasma androstenedione was within the range for normal males and increased markedly following metyrapone in all the cases.

Effects of oestradiol benzoate (OeB) and human chorionic gonadotrophin (hCG) on the testes and accessory sex glands of the rat

1981 ◽  
Vol 96 (2) ◽  
pp. 273-280 ◽  
Author(s):  
Mridula Chowdhury ◽  
Robert Tcholakian ◽  
Emil Steinberger
Keyword(s):  
Treated Group ◽  
Inhibitory Effect ◽  
Male Rats ◽  
Plasma Testosterone ◽  
Control Group ◽  
Intact Male ◽  
Intact Control ◽  
Testosterone Levels ◽  
Oestradiol Benzoate ◽  
Direct Inhibitory Effect

Abstract. It has been suggested that treatment of intact male rats with oestradiol benzoate (OeB) causes an interference with testosterone (T) production by the testes by a direct inhibitory effect on steroidogenesis. To test this hypothesis, different doses (5, 10 or 25 IU) of hCG were administered concomitantly with 50 μg of OeB to adult intact or hypophysectomized male rats. The testicular and plasma testosterone, and serum hCG levels were determined. The sex accessory weights were recorded. In the intact OeB-treated group of animals, hCG stimulated both the secondary sex organs and plasma testosterone levels above the intact control group. However, in hypophysectomized animals, although plasma testosterone levels increased above that of intact controls, their secondary sex organ weights did not. Moreover, inspite of high circulating hCG levels, the testicular testosterone content and concentration remained suppressed in OeB-treated animals. The reason for such dichotomy of hCG action on OeB-treated animals is not clear at present.

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