Neuroendocrinology Research Papers - Academia.edu (original) (raw)

The hormone melatonin regulates the sleep and this pineal hormone is synthesized in the organism from the amino acid tryptophan. It is known that breast-fed babies have better sleep patterns and a better entrained sleep/wake cycle than... more

The hormone melatonin regulates the sleep and this pineal hormone is synthesized in the organism from the amino acid tryptophan. It is known that breast-fed babies have better sleep patterns and a better entrained sleep/wake cycle than bottle-fed babies (adapted formula). To compare the circadian rhythm of 6-sulfatoxymelatonin (aMT6s)--the metabolite of melatonin excreted in the urine--in urine of bottle-fed and breast-fed children, and relate it to the circadian rhythm of tryptophan in breast milk, also evaluating the possible effects on the baby's night-time rest. 16 infants of 12 weeks of age were studied, divided into two groups depending on their exclusively natural or artificial feeding. The circadian rhythm of 6-sulfatoxymelatonin in urine was measured for the two groups of infants and for the breast-feeding mothers. In the breast milk, the circadian rhythm of the amino acid tryptophan was measured. The rest of the infants was tested by wrist actimeters for a week and the...

The effect of sensory input on hormones is essential to any explanation of mammalian behavior, including aspects of physical attraction. The chemical signals we send have direct and developmental effects on hormone levels in other people.... more

The effect of sensory input on hormones is essential to any explanation of mammalian behavior, including aspects of physical attraction. The chemical signals we send have direct and developmental effects on hormone levels in other people. Since we don t know either if, or how, visual cues might have direct and developmental effects on hormone levels in other people, the biological basis for the development of visually perceived human physical attraction is currently somewhat questionable. In contrast, the biological basis for the development of physical attraction based on chemical signals is well detailed.

OBJECTIVE In the present study we aimed at investigating leptin levels in professional male athletes who have been exercising regularly for a long time and leptin levels in healthy sedentary males. METHODS The study included 10 male... more

OBJECTIVE In the present study we aimed at investigating leptin levels in professional male athletes who have been exercising regularly for a long time and leptin levels in healthy sedentary males. METHODS The study included 10 male professional football players and 17 healthy sedentary males. The relations between groups in terms of leptin levels, Max VO2 levels, blood lactic acid levels before and after exercise and effort durations were investigated. RESULTS It was found in the study that although BMI of professional male athletes was higher than that of the healthy sedentary males, leptin levels of the former were significantly lower (p<0.01), while VO2Max levels (p<0.05) and test periods (p<0.01) were significantly higher than those in the latter. As for lactic acid levels after exercise and between groups, these were also higher in athletes, but the difference was not statistically significant (p>0.05). CONCLUSION Leptin levels of those who exercised regularly were...

In mammals, daily rhythms in behaviour and physiology are driven by a circadian timing system comprised, in a hierarchical way, of a master pacemaker in the suprachiasmatic nuclei (SCN) of the hypothalamus and of peripheral oscillators in... more

In mammals, daily rhythms in behaviour and physiology are driven by a circadian timing system comprised, in a hierarchical way, of a master pacemaker in the suprachiasmatic nuclei (SCN) of the hypothalamus and of peripheral oscillators in most body cells. At the molecular level, in both the SCN and peripheral oscillators, the circadian clock mechanism is built from interconnected feedback loops in gene expression that operate in a cell-autonomous and self-sustained fashion. The SCN clock is mainly entrained by light/dark cycles. By contrast, peripheral oscillators can be strongly affected by daily feeding cycles, which have little effect on the phase of the SCN. However, when feeding schedules are coupled with a caloric restriction, behavioural and physiological circadian rhythms and gene expression in the SCN are shifted and/or entrained to meal-time. Moreover, the reward and motivational value of food can also be a potent synchroniser for the SCN clock. This suggests that energy metabolism and motivational properties of food can influence the clock mechanism of the SCN. Food-related cues may entrain clock genes of the SCN with a direct effect, or be mediated indirectly by another neural or peripheral site. In addition, there may be one or more oscillator sites that would play an integral role as a food-entrained oscillator (FEO), responsible for anticipation of meal-time. The site housing, or the network underlying, this putative FEO is still unknown. The aim of this review is to summarise our current knowledge of the central and peripheral circadian clocks and how they can be entrained by feeding at the physiological and molecular levels.

Extensive animal and recent human research have helped inform neuroendocrinological models of social cognition, motivation and behavior. In this review, we first summarize important findings regarding oxytocin, arginine vasopressin and... more

Extensive animal and recent human research have helped inform neuroendocrinological models of social cognition, motivation and behavior. In this review, we first summarize important findings regarding oxytocin, arginine vasopressin and testosterone in the domains of affiliation, social cognition, aggression and stress/anxiety. We then suggest ways in which human research can continue to profit from animal research, particularly by exploring the interactive nature of neuromodulatory effects at neurochemical, organismic and contextual levels. We further propose methods inspired by the animal literature for the ecologically valid assessment of affiliative behavior in humans. We conclude with suggestions for how human research could advance by directly assessing specific social cognitive and motivational mechanisms as intermediate variables. We advocate a more comprehensive look at the distinct networks identified by social neuroscience and the importance of a motivational state, in add...

Retrospective clinical reports suggesting that traumatic stress populations display an increased propensity for glucose metabolism disorders were examined in a controlled prospective animal model. Stress-induced behavioural and... more

Retrospective clinical reports suggesting that traumatic stress populations display an increased propensity for glucose metabolism disorders were examined in a controlled prospective animal model. Stress-induced behavioural and hypothalamic-pituitary-adrenal (HPA) axis response patterns were correlated to central and peripheral parameters of glucose metabolism and signalling, and to body measurements in Sprague–Dawley rats exposed to predator scent stress. Forty days post-exposure, fasting blood glucose and insulin levels, oral glucose tolerance test, body weight and white adipose tissue mass, systemic corticosterone levels and brain expression of insulin receptor (IR) and insulin-sensitive glucose transporter 4 (GLUT4) protein levels were evaluated. In a second experiment inbred strains with hyper- (Fischer) and hypo- (Lewis) reactive HPA axes were employed to assess the association of metabolic data with behavioural phenomenology versus HPA axis response profile. For data analysis, animals were classified according to their individual behavioural response patterns (assessed at day 7) into extreme, partial and minimal response groups. The exposed Sprague–Dawley rats fulfilling criteria for extreme behavioural response (EBR) (20.55%) also exhibited significant increases in body weight, abdominal circumference and abdominal white adipose tissue mass; a hyperglycaemic oral glucose tolerance test; and fasting hyperglycaemia, hyperinsulinaemia and hypercorticosteronemia, whereas minimal responders (MBR) and control animals displayed no such disturbances. Hippocampal and hypothalamic expression of IR and GLUT4 protein were significantly lower in EBR than in MBR and control rats. The inbred strains showed no metabolic differences at baseline. Exposed Fischer rats displayed hyperglycaemia and hyperinsulinaemia, whereas Lewis rats did not. A significant protracted disorder of glucose metabolism was induced by exposure to a stress paradigm. This metabolic response was associated with the characteristic pattern of HPA axis (corticosterone) response, which underlies the behavioural response to stress.

Through an extremely complicated equilibrium called homeostasis, all living organisms maintain their survival in the face of both externally and internally generated "stimuli". This apparent harmony is constantly challenged.... more

Through an extremely complicated equilibrium called homeostasis, all living organisms maintain their survival in the face of both externally and internally generated "stimuli". This apparent harmony is constantly challenged. Survival through successful adaptation is maintained as close to steady state as possible by adaptive responses, which may also be called perturbation responses since they have a constitutively defined dynamic capacity, i.e., an immediate limit, in a series of balancing and feedback activities reflecting an astounding array of biological, psychological and sociological behaviors. The broad spectrum of stimuli capable of engaging this protective response is remarkable. We define stress as a type of stimulation that is stronger and lasts for a longer duration, upsetting a typical perturbation response given its dynamic parameters. The stress response, which evolves out of the perturbation response, involves inducible signal molecules, i.e., cytokines. We...

Animal models have been used extensively to investigate neuropsychiatric disorders, such as depression, and their treatment. However, the aetiology and pathophysiology of many such disorders are largely unknown, which makes validation of... more

Animal models have been used extensively to investigate neuropsychiatric disorders, such as depression, and their treatment. However, the aetiology and pathophysiology of many such disorders are largely unknown, which makes validation of animal models particularly challenging. Furthermore, many diagnostic symptoms are difficult to define, operationalise and quantify, especially in experimental animals such as rats. Thus, rather than attempting to model complex human syndromes such as depression in their entirety, it can be more productive to define and model components of the illness that may account for clusters of co-varying symptoms, and that may share common underlying neurobiological mechanisms. In preclinical investigations of the neural regulatory mechanisms linking stress to depression and anxiety disorders, as well as the mechanisms by which chronic treatment with antidepressant drugs may exert their beneficial effects in these conditions, we have employed a number of behavioural tests in rats to model specific cognitive and anxiety-like components of depression and anxiety disorders. In the present study, we review the procedures for conducting four such behavioural assays: the attentional set-shifting test, the elevated-plus maze, the social interaction test and the shock-probe defensive burying test. The purpose is to serve as a guide to the utility and limitations of these tools, and as an aid in optimising their use and productivity.

This is not an investigation on the sexual habits of Mötley Crüe, neither on drugs of abuse. Rather, reviewing the neuroendocrine literature on music, courtship, orgasm, and attachment, a parallel between music and love is proposed.... more

This is not an investigation on the sexual habits of Mötley Crüe, neither on drugs of abuse. Rather, reviewing the neuroendocrine literature on music, courtship, orgasm, and attachment, a parallel between music and love is proposed. Exapted from mother-infant interactions to mate attraction, fostering neotenization, music reduced inter-male aggression, promoted social cohesion, and had a role in human encephalization. " Sex is a luxury, not a necessity "

Reproduction involves the integration of hormonal signals acting across multiple systems to generate a synchronised physiological output. A critical component of reproduction is the lutein-ising hormone (LH) surge, which is mediated by... more

Reproduction involves the integration of hormonal signals acting across multiple systems to generate a synchronised physiological output. A critical component of reproduction is the lutein-ising hormone (LH) surge, which is mediated by oestradiol (E 2) and neuroprogesterone interacting to stimulate kisspeptin release in the rostral periventricular nucleus of the third ventricle in rats. Recent evidence indicates the involvement of both classical and membrane E 2 and proges-terone signalling in this pathway. A metabolite of gonadotrophin-releasing hormone (GnRH), GnRH-(1-5), has been shown to stimulate GnRH expression and secretion, and has a role in the regulation of lordosis. Additionally, gonadotrophin release-inhibitory hormone (GnIH) projects to and influences the activity of GnRH neurones in birds. Stress-induced changes in GnIH have been shown to alter breeding behaviour in birds, demonstrating another mechanism for the molecular control of reproduction. Peripherally, paracrine and autocrine actions within the gonad have been suggested as therapeutic targets for infertility in both males and females. Dys-function of testicular prostaglandin synthesis is a possible cause of idiopathic male infertility. Indeed, local production of melatonin and corticotrophin-releasing hormone could influence spermatogenesis via immune pathways in the gonad. In females, vascular endothelial growth factor A has been implicated in an angiogenic process that mediates development of the corpus luteum and thus fertility via the Notch signalling pathway. Age-induced decreases in fertility involve ovarian kisspeptin and its regulation of ovarian sympathetic innervation. Finally, morphological changes in the arcuate nucleus of the hypothalamus influence female sexual recep-tivity in rats. The processes mediating these morphological changes have been shown to involve the rapid effects of E 2 controlling synaptogenesis in this hypothalamic nucleus. In summary, this review highlights new research in these areas, focusing on recent findings concerning the molecular mechanisms involved in the central and peripheral hormonal control of reproduction.

A small number of putatively celibate Roman Catholic priests and religious brothers have engaged in immoral and illegal sexual acts with young boys. Many people believe that this is simply a homosexual problem. As a remedy, men who are... more

A small number of putatively celibate Roman Catholic priests and religious brothers have engaged in immoral and illegal sexual acts with young boys. Many people believe that this is simply a homosexual problem. As a remedy, men who are known to have with deep seated homosexual tendencies are no longer welcome in seminaries or men’s religious orders. Yet, men who are sexually attracted to other adult men are no more sexually aroused by pictures of peri-pubescent boys than they are to neutral landscapes. They are not the culprits. To understand who are the high-risk men, the concepts of sex and gender are untangled. An understanding of how the brain is organized in utero and then activated at puberty is explained as a way to understand how a minority of adult men develop a sexual preference for young boys. Several different data sets are reviewed on the prevalence of priests and religious brothers being sexually involved with young boys. The author’s own data that measured the age and gender attractions of hundreds of priests and brothers physiologically are presented. The reality is that men sexually attracted to peri-pubescent boys (pederasts) are undetectable with current methods of screening applicants to priesthood or religious life. They are homosexuals based only on the shape of the young boys’ genitals. They have almost nothing else in common with other homosexual men who are sexually attracted to other adult men. Celibacy attracts homosexuals to priesthood and religious life out of proportion to their prevalence in the general population. The homosexuals attracted to per-pubescent boys are indistinguishable from men sexually attracted to adult women. They cannot be detected by psychological interviews or testing. They almost all say they are heterosexual. The Church has initiated some recent policies to remedy the problem, which in the author’s opinion will only create a temporary lull. The author makes three recommendations to reduce the long-term risks of priests and religious brothers being sexual with peri-pubescent boys, and justifies the bases for these recommendations in the chapter: (1) allow diocesan priests to marry, (2) allow married persons to become priests, and (3) allow married persons and women into the Church hierarchy where current policies are contributing causes to the problems and where it is not in the best interest of the current decision makers to change policies in ways that would allow the three recommendations given to be implemented.

Diagnostic criteria for mood disorders including major depressive disorder (MDD) largely ignore biological factors in favor of behavioral symptoms. Compounding this paucity of psychiatric biomarkers is a need for therapeutics to... more

Diagnostic criteria for mood disorders including major depressive disorder (MDD) largely ignore biological factors in favor of behavioral symptoms. Compounding this paucity of psychiatric biomarkers is a need for therapeutics to adequately treat the 30-50% of MDD patients who are unresponsive to traditional antidepressant medications. Interestingly, MDD is highly prevalent in patients suffering from chronic inflammatory conditions, and MDD patients exhibit higher levels of circulating pro-inflammatory cytokines. Together, these clinical findings suggest a role for the immune system in vulnerability to stress-related psychiatric illness. A growing body of literature also implicates the immune system in stress resilience and coping. In this review, we discuss the mechanisms by which peripheral and central immune cells act on the brain to affect stress-related neurobiological and neuroendocrine responses. We specifically focus on the roles of pro-inflammatory cytokine signaling, peripheral monocyte infiltration, microglial activation and hypothalamic-pituitary-adrenal (HPA) axis hyperactivity in stress vulnerability. We also highlight recent evidence suggesting that adaptive immune responses and treatment with immune modulators (exogenous glucocorticoids, humanized antibodies against cytokines) may decrease depressive symptoms and thus represent an attractive alternative to current antidepressant treatments.

The alliance theory holds that homosexual behavior in humans may have evolved because it reinforced same-sex alliances which contributed to survival and reproduction. The present study was designed to test this evolutionary hypothesis in... more

The alliance theory holds that homosexual behavior in humans may have evolved because it reinforced same-sex alliances which contributed to survival and reproduction. The present study was designed to test this evolutionary hypothesis in view of the strongly negative perception of homosexual behavior. It was predicted that targets who engaged in homosexual behavior would be perceived as likely to achieve greater social status and reproductive opportunities when the behavior reinforced an alliance that led to increased social opportunities. Three hundred sixteen men and women read scenarios in which a target engaged in homosexual behavior and then answered questions about the target's future social status and reproductive opportunities as measured by number of sexual partners. The data were analyzed in two 3 (social outcome: positive vs. neutral vs. negative) x 2 (gender of target) x 2 (gender of participant) analyses of variance. The results supported the predictions and demonst...

In this chapter, I investigate the effects of the hormonal birth control pill on the female brain, cognition and behavior. Using knowledge gathered from the biological, behavioral and the neurological sciences, I first discuss the effects... more

In this chapter, I investigate the effects of the hormonal birth control pill on the female brain, cognition and behavior. Using knowledge gathered from the biological, behavioral and the neurological sciences, I first discuss the effects of the COC on the neuroendocrine (hormonal) systems of the brain, and effects seen on brain development. I then consider the effects of the COC on cognitive performance and social behaviors, and link these to the current body of research on the influences on the biological mechanisms at the basis of these behaviors. It is the primary goal of this research to identify how the birth control pill affects its users; therefore, this paper shall focus on some of the most clearly observed differences between users and non-users.

The existence of dopamine (DA)-melatonin (aMT) relationships is well documented in several brain areas of the mammalian central nervous system such as the retina and hypothalamus or the nigrostriatal system. For instance, aMT tempers 1... more

The existence of dopamine (DA)-melatonin (aMT) relationships is well documented in several brain areas of the mammalian central nervous system such as the retina and hypothalamus or the nigrostriatal system. For instance, aMT tempers 1 methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced nigrostriatal damage in C57BL/6 mice. In this mouse strain however, rhythmic production of aMT and its possible interaction with striatal DA is still unclear.

In female sheep and goats, exposure to males can be used to induce ovulation and thus control and synchronise fertility. This ‘male effect’ offers simple, cost-effective, and hormone-free management of reproduction in flocks and herds... more

In female sheep and goats, exposure to males can be used to induce ovulation and thus control and synchronise fertility. This
‘male effect’ offers simple, cost-effective, and hormone-free management of reproduction in flocks and herds but, despite decades of
research, significant gaps in our knowledge impede commercial application. Many of these gaps can be traced back to misconceptions in the early documentation of the male effect, and others are the result of uncontrolled factors in experimental design. Consequently, it is
often difficult to draw conclusions from past research, to further our understanding of the phenomenon, and to make recommendations
for industry application. Here, we describe 2 aspects of the male stimulus used to elicit the male effect that are often uncontrolled – the
novelty of the stimulus males and factors that contribute to variability in the potency of the male stimulus. We discuss the physiology
that underpins novelty, including the individual specificity of the socio-sexual signals emitted by the male, and the concomitant ability
of females to distinguish among individual males and remember them. Importantly, an understanding of the issue of novelty can make
it easier to use the male effect in commercial practice. We also discuss difficulties in interpretation caused by variation in endpoints of
the male effect (from neuroendocrine reaction to birth). We conclude that more rigour is needed in the control and reporting of male
novelty, in pre-experimentation separation of the sexes, and in extrapolation from detection of early responses to the male stimulus to
reproductive outcomes.

As a female transitions into motherhood, many neurobiological adaptations are required to meet the demands presented by her offspring. In addition to the traditional maternal responses (e.g. crouching, nursing, retrieving, grooming), our... more

As a female transitions into motherhood, many neurobiological adaptations are required to meet the demands presented by her offspring. In addition to the traditional maternal responses (e.g. crouching, nursing, retrieving, grooming), our laboratories have observed several behavioural modifications accompanying parity, especially in the areas of foraging and emotional resilience. Additionally, brain modifications have been observed in the hippocampus and amygdala, providing support for neural plasticity extending beyond the expected hypothalamic alterations. Interestingly, we have observed parenting-induced neuroplasticity to persist into late adulthood, even providing protection against age-related brain and memory deficits. Although the majority of work on the parental brain has been conducted on females, preliminary research suggests similar changes in the biparental male California deer mouse. Taken together, research suggests that the parental brain is dynamic and changeable as it undergoes diverse and, in some cases, long-lasting, modifications to facilitate the production and care of offspring.

Significance has been attached to the pineal gland in numerous different cultures and beliefs. One religion that has advanced the role of the pineal gland is Spiritism. The objective of the present study was to compile information on the... more

Significance has been attached to the pineal gland in numerous different cultures and beliefs. One religion that has advanced the role of the pineal gland is Spiritism. The objective of the present study was to compile information on the pineal gland drawing on the books of Francisco Cândido Xavier written through psychography and to carry out a critical analysis of their scientific bases by comparing against evidence in the current scientific literature. A systematic search using the terms "pineal gland" and "epiphysis" was conducted of 12 works allegedly dictated by the spirit "André Luiz". All information on the pineal having potential correlation with the field of medicine and current studies was included. Specialists in the area were recruited to compile the information and draw parallels with the scientific literature. The themes related to the pineal gland were: mental health, reproductive function, endocrinology, relationship with physical activ...

Over the past two decades, the classical understanding of steroid action has been updated to include rapid, membrane-initiated, neurotransmitter-like functions. While steroids were known to function on very short time spans to induce... more

Over the past two decades, the classical understanding of steroid action has been updated to include rapid, membrane-initiated, neurotransmitter-like functions. While steroids were known to function on very short time spans to induce physiological and behavioral changes, the mechanisms by which these changes occur are now becoming more clear. In avian systems, rapid estradiol effects can be mediated via local alterations in aromatase activity, which precisely regulates the temporal and spatial availability of estrogens. Acute regulation of brain-derived estrogens has been shown to rapidly affect sensorimotor function and sexual motivation in birds. In rodents, estrogens and progesterone are critical for reproduction, including preovulatory events and female sexual receptivity. Membrane pro-gesterone receptor as well as classical progesterone receptor trafficked to the membrane mediate reproductive-related hypothalamic physiology, via second messenger systems with dopamine-induced cell signals. In addition to these relatively rapid actions, estrogen membrane-initiated signaling elicits changes in morphology. In the arcuate nucleus of the hypothalamus, these changes are needed for lordosis behavior. Recent evidence also demonstrates that membrane glucocorticoid receptor is present in numerous cell types and species, including mammals. Further, membrane glucocorticoid receptor influences glucocorticoid receptor translocation to the nucleus effecting transcriptional activity. The studies presented here underscore the evidence that steroids behave like neurotransmitters to regulate CNS functions. In the future, we hope to fully characterize steroid receptor-specific functions in the brain.