scholarly journals Asas-Ssr Triennial Reproduction Symposium: Looking Back And Moving Forward—How Reproductive Physiology Has Evolved: Male reproductive behavior: sensory signaling in the brain of low-performing domestic rams1

2018 ◽  
Author(s):  
Brenda M Alexander
Keyword(s):  
Reproductive Behavior ◽  
Reproductive Physiology ◽  
Sensory Signaling ◽  
Male Reproductive Behavior ◽  
The Brain ◽  
Looking Back

scholarly journals Acute Stress Differentially Affects Aromatase Activity in Specific Brain Nuclei of Adult Male and Female Quail

Endocrinology ◽  
2011 ◽  
Vol 152 (11) ◽  
pp. 4242-4251 ◽  
Author(s):  
Molly J. Dickens ◽  
Charlotte A. Cornil ◽  
Jacques Balthazart
Keyword(s):  
Reproductive Behavior ◽  
Acute Stress ◽  
Aromatase Activity ◽  
Brain Nuclei ◽  
Male And Female ◽  
Estrogen Production ◽  
Female Quail ◽  
Male Reproductive Behavior ◽  
The Individual ◽  
The Brain

The rapid and temporary suppression of reproductive behavior is often assumed to be an important feature of the adaptive acute stress response. However, how this suppression operates at the mechanistic level is poorly understood. The enzyme aromatase converts testosterone to estradiol in the brain to activate reproductive behavior in male Japanese quail (Coturnix japonica). The discovery of rapid and reversible modification of aromatase activity (AA) provides a potential mechanism for fast, stress-induced changes in behavior. We investigated the effects of acute stress on AA in both sexes by measuring enzyme activity in all aromatase-expressing brain nuclei before, during, and after 30 min of acute restraint stress. We show here that acute stress rapidly alters AA in the male and female brain and that these changes are specific to the brain nuclei and sex of the individual. Specifically, acute stress rapidly (5 min) increased AA in the male medial preoptic nucleus, a region controlling male reproductive behavior; in females, a similar increase was also observed, but it appeared delayed (15 min) and had smaller amplitude. In the ventromedial and tuberal hypothalamus, regions associated with female reproductive behavior, stress induced a quick and sustained decrease in AA in females, but in males, only a slight increase (ventromedial) or no change (tuberal) in AA was observed. Effects of acute stress on brain estrogen production, therefore, represent one potential way through which stress affects reproduction.

Population Numbers and Reproductive Health

Endocrinology ◽  
2021 ◽  
Vol 162 (11) ◽  
Author(s):  
Alexander Suvorov
Keyword(s):  
Reproductive Behavior ◽  
Alternative Hypothesis ◽  
Experimental Studies ◽  
Causal Chain ◽  
Reproductive Physiology ◽  
Global Changes ◽  
Population Densities ◽  
Related Factors ◽  
And Behavior ◽  
Population Numbers

Abstract A recent study published in The Lancet predicts a remarkable drop in population numbers following a peak that will be reached by 2064. A unique feature of the upcoming population drop is that it will be almost exclusively caused by decreased reproduction, rather than factors that increase rates of mortality. The reasons for decreased reproduction are also unique, as, unlike previous centuries, limited reproduction today is hardly due to a shortage in resources. In other words, the predicted population drop is almost exclusively due to changes in reproductive behavior and reproductive physiology. Today, global changes in reproductive behavior are mostly explained by social sciences in a framework of demographic transition hypotheses, while changes in reproductive physiology are usually attributed to effects of endocrine-disrupting pollutants. This review outlines a complementary/alternative hypothesis, which connects reproductive trends with population densities. Numerous wildlife and experimental studies of a broad range of animal species have demonstrated that reproductive behavior and reproductive physiology are negatively controlled via endocrine and neural signaling in response to increasing population densities. The causal chain of this control system, although not fully understood, includes suppression of every level of hypothalamic-pituitary-gonadal cascade by hypothalamic-pituitary-adrenal axis, activated in response to increasing stress of social interactions. This paper discusses evidence in support of a hypothesis that current trends in reproductive physiology and behavior may be partly explained by increasing population densities. Better understanding of the causal chain involved in reproduction suppression by population density–related factors may help in developing interventions to treat infertility and other reproductive conditions.

scholarly journals Information theory and the neuropeptidergic regulation of seasonal reproduction in mammals and birds

2011 ◽  
Vol 278 (1717) ◽  
pp. 2477-2485 ◽  
Author(s):  
Tyler J. Stevenson ◽  
Gregory F. Ball
Keyword(s):  
Mammalian Species ◽  
Reproductive Physiology ◽  
Environmental Cues ◽  
Naturally Occurring ◽  
Contingency Model ◽  
Neural Integration ◽  
Gonadotrophin Releasing Hormone ◽  
Environmental Amelioration ◽  
The Impact ◽  
The Brain

Seasonal breeding in the temperate zone is a dramatic example of a naturally occurring change in physiology and behaviour. Cues that predict periods of environmental amelioration favourable for breeding must be processed by the brain so that the appropriate responses in reproductive physiology can be implemented. The neural integration of several environmental cues converges on discrete hypothalamic neurons in order to regulate reproductive physiology. Gonadotrophin-releasing hormone-1 (GnRH1) and Kisspeptin (Kiss1) neurons in avian and mammalian species, respectively, show marked variation in expression that is positively associated with breeding state. We applied the constancy/contingency model of predictability to investigate how GnRH1 and Kiss1 integrate different environmental cues to regulate reproduction. We show that variation in GnRH1 from a highly seasonal avian species exhibits a predictive change that is primarily based on contingency information. Opportunistic species have low measures of predictability and exhibit a greater contribution of constancy information that is sex-dependent. In hamsters, Kiss1 exhibited a predictive change in expression that was predominantly contingency information and is anatomically localized. The model applied here provides a framework for studies geared towards determining the impact of variation in climate patterns to reproductive success in vertebrate species.

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