A possible endocrine mechanism for inducing diapause in the eggs ofAdelphocoris lineolatus (Goeze) (Hemiptera: Miridae)

1966 ◽  
Vol 22 (7) ◽  
pp. 470-470 ◽  
Author(s):  
A. B. Ewen
Keyword(s):  
Endocrine Mechanism

scholarly journals Social and endocrine correlates of immune function in meerkats: implications for the immunocompetence handicap hypothesis

2018 ◽  
Vol 5 (8) ◽  
pp. 180435 ◽  
Author(s):  
Kendra N. Smyth ◽  
Nicholas M. Caruso ◽  
Charli S. Davies ◽  
Tim H. Clutton-Brock ◽  
Christine M. Drea
Keyword(s):  
Immune Function ◽  
Social Status ◽  
Dominant Species ◽  
Reproductive Activity ◽  
Trade Offs ◽  
Endocrine Mechanism ◽  
Immunocompetence Handicap Hypothesis ◽  
Handicap Hypothesis ◽  
Serum Bacteria ◽  
Bacteria Killing

Social status can mediate effects on the immune system, with profound consequences for individual health; nevertheless, most investigators of status-related disparities in free-ranging animals have used faecal parasite burdens to proxy immune function in the males of male-dominant species. We instead use direct measures of innate immune function (complement and natural antibodies) to examine status-related immunocompetence in both sexes of a female-dominant species. The meerkat is a unique model for such a study because it is a cooperatively breeding species in which status-related differences are extreme, evident in reproductive skew, morphology, behaviour, communication and physiology, including that dominant females naturally express the greatest total androgen (androstenedione plus testosterone) concentrations. We found that, relative to subordinates, dominant animals had reduced serum bacteria-killing abilities; also, relative to subordinate females, dominant females had reduced haemolytic complement activities. Irrespective of an individual's sex or social status, androstenedione concentrations (but not body condition, age or reproductive activity) negatively predicted concurrent immunocompetence. Thus, dominant meerkats of both sexes are immunocompromised. Moreover, in female meerkats, androstenedione perhaps acting directly or via local conversion, may exert a double-edged effect of promoting dominance and reproductive success at the cost of increased parasitism and reduced immune function. Given the prominent signalling of dominance in female meerkats, these findings may relate to the immunocompetence handicap hypothesis (ICHH); however, our data would suggest that the endocrine mechanism underlying the ICHH need not be mediated solely by testosterone and might explain trade-offs in females, as well as in males.

Cortisol responsiveness and dominance rank, but not baseline cortisol level, are repeatable traits in adult female guinea pigs

2021 ◽  
Author(s):  
Taylor Lynne Rystrom ◽  
Romy C. Prawitt ◽  
S. Helene Richter ◽  
Norbert Sachser ◽  
Sylvia Kaiser
Keyword(s):  
Social Behavior ◽  
Adult Female ◽  
Guinea Pigs ◽  
Dominance Rank ◽  
Dominance Hierarchies ◽  
Current State ◽  
Baseline Cortisol ◽  
Group Members ◽  
Endocrine Mechanism ◽  
Males And Females

Social interactions among group members often lead to the formation of stable dominance hierarchies. Glucocorticoids (i.e. cortisol) have been proposed as an endocrine mechanism underlying social behavior, and previous studies have linked baseline as well as challenge glucocorticoid concentrations to dominance rank. Since the importance of rank on fitness differs between males and females, selection pressures acting on the underlying endocrine mechanisms may differ between the sexes. In male guinea pigs, for example, it is known that cortisol responsiveness mediates social behavior and that dominance rank and cortisol responsiveness are stable within individuals over time. It is unclear whether this is also the case for female guinea pigs. Thus the aim of this study was to investigate whether cortisol concentrations are repeatable in female guinea pigs and whether female rank is correlated to baseline cortisol concentrations or cortisol responsiveness. We show that cortisol responsiveness and dominance rank were significantly repeatable but not correlated in female guinea pigs. Furthermore, baseline cortisol was not repeatable and also did not correlate to dominance rank. Our results demonstrate that baseline cortisol and cortisol responsiveness represent different biological processes; cortisol responsiveness reflects a stable trait while baseline cortisol likely fluctuates with current state. Furthermore, cortisol responsiveness as a mediator of aggressive behavior and dominance acquisition might not be important for maintaining dominance hierarchies in stable groups of females displaying minimal aggression. Overall, this study reveals the remarkable stability of cortisol responsiveness and dominance rank in an adult female rodent and lays the groundwork for future investigations into the causes and consequences of this individual variation.

Cholecystokinin suppresses food intake by a nonendocrine mechanism in rats

1994 ◽  
Vol 267 (4) ◽  
pp. R901-R908 ◽  
Author(s):  
R. D. Reidelberger ◽  
G. Varga ◽  
R. M. Liehr ◽  
D. A. Castellanos ◽  
G. L. Rosenquist ◽  
...  
Keyword(s):  
Food Intake ◽  
Pancreatic Enzyme ◽  
Free Access ◽  
Amylase Secretion ◽  
Receptor Antagonists ◽  
Feeding Experiments ◽  
Pancreatic Enzyme Secretion ◽  
Endocrine Mechanism ◽  
Access To Food ◽  
Cck Receptor Antagonists

A cholecystokinin monoclonal antibody (CCK MAb) was used to immunoneutralize CCK to test the hypothesis that CCK produces satiety by an endocrine mechanism. We first characterized the effects of CCK MAb on pancreatic secretion. Conscious rats with jugular vein and bile-pancreatic duct cannulas received CCK MAb or control antibody intravenously 30 min before a 2-h maximal dose of CCK-8 (200 pmol.kg-1.h-1 i.v.) or access to food. CCK MAb caused dose-related inhibition of amylase secretion. CCK MAb (2 mg/kg) completely blocked the response to CCK-8 and inhibited the response to food by 89%. In feeding experiments, rats with free access to food received CCK MAb or control antibodies (2 mg/kg iv) 2 h after lights off. CCK MAb had no effect on 1.5- or 3.5-h food intake. Another group of rats received CCK MAb (4 mg/kg i.v.) or a combined injection of type A and type B CCK receptor antagonists devazepide and L-365,260 (1 mg/kg each i.v.). CCK MAb had no effect on feeding, whereas the receptor antagonists stimulated 1-, 2-, 3-, and 4-h intake by 62, 45, 43, and 29%. These results suggest that endogenous CCK stimulates pancreatic enzyme secretion at least partially by an endocrine mechanism and produces satiety by a nonendocrine mechanism.

scholarly journals CONSIDERAION ON THE ENDOCRINE MECHANISM OF OVULATION IN THE MARE.

1947 ◽  
Vol 9 (1-2) ◽  
pp. 47-54
Author(s):  
YOSHISUKE SUZUKI ◽  
TOSHIRO HOSI
Keyword(s):  
Endocrine Mechanism

Possible mechanism for the first response to short captivity stress in the water frog, Rana esculenta

1996 ◽  
Vol 148 (2) ◽  
pp. 233-239 ◽  
Author(s):  
A Gobbetti ◽  
M Zerani
Keyword(s):  
Rana Esculenta ◽  
Prostaglandin E ◽  
Aromatase Activity ◽  
Male And Female ◽  
Water Frog ◽  
First Response ◽  
Prostaglandin F ◽  
Endocrine Mechanism ◽  
The Brain ◽  
Time Point

Abstract To clarify the endocrine mechanism involved in the short captivity stress in the water frog, Rana esculenta, the activity of 9-ketoreductase, the enzyme which converts prostaglandin E2 (PGE2) into prostaglandin F2α (PGF2α), and aromatase, which converts testosterone into oestradiol-17β, were studied. Adult male and female frogs were sacrificed 0, 1·5, 3, 6, 12, 24, 48, 72, 168 and 336 h after capture in the field. PGE2, PGF2α, progesterone, testosterone, oestradiol-17β and corticosterone plasma levels were detected by RIA at each time point. 9-Ketoreductase (conversion of [3H]PGE2 into [3H]PGF2α) and aromatase (conversion of [3H]testosterone into [3H]oestradiol-17β) activities in the brain, testis, ovary and interrenal were also determined at each time point. After capture, levels of plasma PGF2α increased (male: 228%; female: 288%) and PGE2 decreased (male: 68%; female: 81%) at 1·5 h, oestradiol-17β increased (male: 399%; female: 425%) and testosterone decreased (male: 87%; female: 83%) at 6 h, and corticosterone increased (male: 421%; female: 426%) at 72 h. 9-Ketoreductase activity in the brain was enhanced at 1·5 h after capture (male: 249%; female: 262%); aromatase activity increased at 6 h in the testis (261%), ovary (273%) and interrenal (male: 227%; female: 267%). These results indicate that short captivity stress could induce an increase in plasma PGF2α through activation of brain 9-ketoreductase. In turn, PGF2α might enhance the levels of circulating oestradiol-17β through activation of gonadal and interrenal aromatase. Journal of Endocrinology (1996) 148, 233–239

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