The involvement of voltage-operated calcium channels in somato-dendritic oxytocin release.

Magnocellular neurons of the supraoptic nucleus (SON) secrete oxytocin and vasopressin from axon terminals in the neurohypophysis, but they also release large amounts of peptide from their somata and dendrites, and this can be regulated both by activity-dependent Ca(2+) influx and by mobilization of intracellular Ca(2+). This somato-dendritic release can also be primed by agents that mobilise intracellular Ca(2+), meaning that the extent to which it is activity-dependent, is physiologically labile. We investigated the role of different Ca(2+) channels in somato-dendritic release; blocking N-type channels reduced depolarisation-induced oxytocin release from SONs in vitro from adult and post-natal day 8 (PND-8) rats, blocking L-type only had effect in PND-8 rats, while blocking other channel types had no significant effect.

Preterm labour: tsunami waves?

Preterm labour and birth can be delayed but are generally unstoppable, threatening the health of the mother-baby duo. This may be a result of peripheral signals prematurely recruiting the oxytocin neurones that co-ordinate the timing of birth and, via specialised activity and secretion patterns, drive uterine contractions. Once sensitised, these neurones respond with waves of activity, even to weak stimuli, resulting in a positive-feedback loop that escalates towards inevitable birth.

Mother-offspring dialogue in early pregnancy: impact of adverse environment on pregnancy maintenance and neurobiology.

The mother-offspring dialogue begins even before implantation and is essential to signal pregnancy, establish robust contact, and maintain embryo growth and development. Any circumstance that disrupts the dialogue risks pregnancy problems. A new look at how stress impacts on pregnancy involves its adverse effects on the key pregnancy hormones of progesterone and prolactin.

Dopamine and oxytocin interactions underlying behaviors: potential contributions to behavioral disorders.

Dopamine is an important neuromodulator that exerts widespread effects on the central nervous system (CNS) function. Disruption in dopaminergic neurotransmission can have profound effects on mood and behavior and as such is known to be implicated in various neuropsychiatric behavioral disorders including autism and depression. The subsequent effects on other neurocircuitries due to dysregulated dopamine function have yet to be fully explored.

Baby on board: do responses to stress in the maternal brain mediate adverse pregnancy outcome?

Stress and adverse environmental surroundings result in suboptimal conditions in a pregnant mother such that she may experience poor pregnancy outcome including complete pregnancy failure and preterm labor. Furthermore her developing baby is at risk of adverse programming, which confers susceptibility to long term ill health. While some mechanisms at the feto-maternal interface underlying these conditions are understood, the underlying cause for their adverse adaptation is often not clear.

Stress in early pregnancy: maternal neuro-endocrine-immune responses and effects.

Stress profoundly compromises reproduction, particularly when experienced in early gestation. One outcome is pregnancy failure: although glucocorticoids have adverse effects it is not clear what their role in pregnancy failure is. However, secretion of vital hormones such as progesterone and prolactin are reduced and this unbalances the delicate and important pregnancy-protective cytokine milieu.

Reduced hypothalamo-pituitary-adrenal axis stress responses in late pregnancy: central opioid inhibition and noradrenergic mechanisms.

In late pregnancy, the hypothalamo-pituitary-adrenal (HPA) axis is less responsive to a range of psychological and physical stressors as a result of reduced central drive to the corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus (PVN). Most stressors activate the brain stem noradrenergic system, which innervates the majority of networks involved in regulating stress responses, including the PVN. Forced swimming, systemic interleukin-1beta (IL-1beta), and cholecystokinin (CCK) all activate brain stem noradrenergic cell groups, stimulate noradrenaline release in the PVN, and activate the HPA axis in nonpregnant rats.

Oxytocin and the maternal brain.

Oxytocin released within the brain from both magnocellular and parvocellular systems of the hypothalamus has diverse effects on behavior. When oxytocin is released within the brain, its effects are to diminish fearfulness; this not only encourages social investigation of newcomers, but also may enhance a tendency to express aggression toward an intruder. Oxytocin supports social recognition, redirects behavior away from feeding directed behavior toward sexual behavior, and facilitates the formation of social bonds.

Interactions between dopamine and oxytocin in the control of sexual behaviour.

Dopamine and oxytocin are two key neuromodulators involved in reproductive behaviours, such as mating and maternal care. Much evidence underlies their separate roles in such behaviours, but particularly in sexual behaviour. It is generally believed that central dopaminergic and oxytocinergic systems work together to regulate the expression of penile erection, but relatively little is known regarding how they interact.

Early risk factors for miscarriage: a prospective cohort study in pregnant women.

Many pregnancies are lost during early gestation, but clinicians still lack tools to recognize risk factors for miscarriage. Thus, the identification of risk factors for miscarriage during the first trimester in women with no obvious risk for a pregnancy loss was the aim of this prospective cohort trial. A total of 1098 women between gestation weeks 4 and 12 in whom no apparent signs of a threatened pregnancy could be diagnosed were recruited.

Dynamic changes in oxytocin receptor expression and activation at parturition in the rat brain.

Oxytocin plays a pivotal role in rat parturition, acting within the brain to facilitate its own release in the supraoptic nucleus (SON) and paraventricular nucleus, and to stimulate maternal behavior. We investigated oxytocin receptor (OTR) expression and activation perinatally. Using a (35)S-labeled riboprobe complementary to OTR mRNA, OTR expression was quantified in proestrus virgin, 21- and 22-day pregnant, parturient (90 min.

Neuroendocrine mechanisms of change in food intake during pregnancy: a potential role for brain oxytocin.

During pregnancy body weight, and particularly adiposity, increase, due to hyperphagia rather than decreased energy metabolism. These physiological adaptations provide the growing fetus(es) with nutrition and prepare the mother for the metabolically-demanding lactation period following birth. Mechanisms underlying the hyperphagia are still poorly understood.

Prenatal stress enhances susceptibility of murine adult offspring toward airway inflammation.

Allergic asthma is one of the most prevalent and continuously increasing diseases in developed countries. Its clinical features include airway hyperresponsiveness and inflammation upon allergen contact. Furthermore, an emerging area of research subsumed as fetal programming evaluates the impact of environmental insults in utero on the incidence of diseases in later life.

Brain oxytocin correlates with maternal aggression: link to anxiety.

The oxytocinergic system is critically involved in the regulation of maternal behavior, which includes maternal aggression. Because aggression has been linked to anxiety, we investigated the maternal aggression and the role of brain oxytocin in lactating Wistar rats selectively bred for high anxiety-related behavior (HAB) or low anxiety-related behavior (LAB) during the 10 min maternal defense test. HAB dams displayed more maternal aggression against a virgin intruder compared with LAB dams, resulting in more defensive behavior and higher anxiety of HAB-defeated virgins.

Central noradrenergic mechanisms underlying acute stress responses of the Hypothalamo-pituitary-adrenal axis: adaptations through pregnancy and lactation.

Hypothalamo-pituitary-adrenal axis responses to stress are attenuated perinatally, and may contribute towards conservation of energy stores and/or prevention of overexposure to glucocorticoid and its adverse effects in the developing fetus/neonate. Previous work has shown that reduced central drive to the hypothalamo-pituitary-adrenal axis is responsible, since parvocellular paraventricular nucleus neurone responses are reduced. One of the main input pathways to the paraventricular nucleus that is activated by the majority of stressors is the brainstem noradrenergic system.

Programming the offspring of the pig by prenatal social stress: neuroendocrine activity and behaviour.

This study provides evidence in the pig that stress experienced during gestation has long-lasting effects on offspring daughters, including their maternal behaviour. Thirty-six primiparous sows were divided into control and two groups that were stressed (by social mixing) during either the second (Mix 2) or third (Mix 3) trimester of pregnancy. We found detrimental effects of mixing on the mothers' growth, body lesions, and cortisol secretion, but did not observe any significant effects on reproductive parameters including birth weight.

Endogenous opioids and attenuated hypothalamic-pituitary-adrenal axis responses to immune challenge in pregnant rats.

In late pregnant rats, the hypothalamic-pituitary-adrenal (HPA) axis is hyporesponsive to psychogenic stressors. Here, we investigated attenuated HPA responses to an immune challenge and a role for endogenous opioids. ACTH and corticosterone were assayed in blood samples from virgin and 21 d pregnant rats before and after endotoxin [lipopolysaccharide (LPS); 1 microg/kg, i.

Regulation of neuronal nitric oxide synthase mRNA expression in the rat magnocellular neurosecretory system.

We examined the activation of nNOS mRNA expression within the supraoptic and paraventricular nuclei (SON and PVN) of the hypothalamus. In salt-loaded rats nNOS mRNA expression was significantly increased in both nuclei. In rats given i.

The progesterone derivative dydrogesterone abrogates murine stress-triggered abortion by inducing a Th2 biased local immune response.

Stress is known to induce abortions in mice and humans, putatively via increased levels of abortogenic Th1 cytokines and a decrease of progesterone. Adequate levels of progesterone exert an antiabortive response through binding to the progesterone-receptor, which induces the release of progesterone-induced blocking factor (PIBF) from lymphocytes. PIBF is highly pregnancy-protective by induction of a Th2 biased immune activity.

Alpha-melanocyte-stimulating hormone stimulates oxytocin release from the dendrites of hypothalamic neurons while inhibiting oxytocin release from their terminals in the neurohypophysis.

The peptides alpha-melanocyte stimulating hormone (alpha-MSH) and oxytocin, when administered centrally, produce similar behavioral effects. alpha-MSH induces Fos expression in supraoptic oxytocin neurons, and alpha-MSH melanocortin-4 receptors (MC4Rs) are highly expressed in the supraoptic nucleus, suggesting that alpha-MSH and oxytocin actions are not independent. Here we investigated the effects of alpha-MSH on the activity of supraoptic neurons.

Neuroendocrine responses to stress in mice: hyporesponsiveness in pregnancy and parturition.

Hypothalamo-pituitary-adrenal axis secretory responses to stress were compared in female virgin, late pregnant, parturient, and lactating mice. The basal plasma ACTH concentration was not different in pregnancy or lactation compared with virgins, but corticosterone concentration and corticosteroid-binding globulin capacity were greatly elevated in late pregnancy. Secretory responses to novel environment were attenuated in pregnant, but not lactating, mice compared with virgin females, whereas ACTH responses to forced swimming were attenuated in both groups.