Regulation of stress responses

 STRESS: reaction, a series of phenomena of metabolic adaptation of an organism ESTRENAR environment, stress, pressure means, a body subjected to stress puts in place a range of adaptive stimuli or general adaptation syndrome that is characterized by:

1) alarm reaction, 2) phase of resistance, 3) stage of exhaustion.

From the perspective of mental stress in the long run is responsible for "Neuropsychiatric Syndroms" featuring iperticorticosolismo, increase of excitatory neurotransmitters.

Paintings neuropsychiatric condition resulting from stressors:

1) priory anxiety disorder (disorder anxiety-inducing)

2) depression

4) anorexia nervosa

5) obsessive - compulsive desorder



Pathophysiology of stress.

The main mech. adaptive body put in place in Phase 1 is represented the activation of the hypothalamic-pituitary-sinsurrene with secretion of ACTH and subsequent stimulation of the cortex. A recent theory claims that a substance called corticotropin releasing factor (CRF) coordinates and modulates, directly or indirectly throughout the adaptive response to stimuli. This is a neuropeptide consisting of 41 amino acids, described by a group of researchers at the Salk Institute in La Jolla, California.

With the synthesis and its marking was possible to identify its distribution in the CNS, registering its concentrations in various brain areas and to ensure that the highest concentration is found in the hypothalamus, the location of the paraventricular nucleus, whose pericari and the secernone flow into the system portale.La its presence in the limbic system (amygdala, hippocampus and stria terminalis) explains the relationship with the regulation of memory processes and behavior and the regulation of autonomic nervous system stress.

Possible applications of CRF in biology:

a) differential diagnosis with Cushing whether hypothalamic or pituitary origin;

b) diagnosis. Differ. with Addison's disease, whether hypothalamic or pituitary;

c) atrophy of the adrenal cortex;

d) decoupling between the hypothalamus and pituitary.

It also allows to understand the physiology of stress.

. Sull'ipofisi The CRF determines an increase in production of hormone ACTH, Beta-endorphin, a hormone melanocortin, MSH, the final outcome is the production of glucocorticoid hormones, thus effects on metabolism, reproduction, inflammation and immunity; interesting is emphasized as progesterone, deoxycorticosterone have an inhibitory function on the GABAergic system (whose activation leads to sedation) through GABA A, with similar action to benzodiazepines, other ormini as dehydroepiandrosterone (DHEA) have GABA-antagonistic action with effect type of anxiety-provoking.

The adaptive response to stress not only modulated by CRF secretion of pituitary hormones, but involves direct neural connection through most of the neurotransmitter. So the administration of CRF in the brain leads to secretion of catecholamines and, in particular, norepinephrine, through stimulation of the locus coeruleus, adrenaline, glucose and glucagon. Although serotonin (5HT) participates in the adaptive response with a mechanism similar to that described for catecholamines, but its depletion is observed only after stimulation intense relationships with Ach are less intense than other neurotransmitters. More interesting is the relationship with CRF and GABAergic system. In fact there is initially a liberation from the globus pallidus, then in the chronic stimulation leads to a reduction of GABA receptor (thus resulting was agitated and anxious) and has a binding STBPS level of chloride channels. He also mentioned the role of CRF and endogenous opioids, produced in many brain areas where it also frees the peptide NPV, area preottica medial nucleus of the stria terminalis less, periventricular hypothalamic nucleus: dynorphin is released, and prodinorfina metenkefalina (peptides related and reduced perception of pain, fatigue, feeling of wellbeing and energy, etc..) in the caudate nucleus and globus pallidus. In experimental CRF causes a motor response, with increased locomotion, while reducing the social interactivity and increases aggression in male and female sexual receptivity is reduced (to emphasize that sexuality is a function of the parasympathetic system not dell'ortosimpatico and catecholamine neurotransmitters). Monkeys whose CNS is closer to humans, there will, therefore, after administration of CRF, an increase of locomotion, blood pressure, muscle dell'irrorazione, tachycardia, increased vocalization, but proceed with the administration, at doses of 180 micrograms, the monkey loses his combative attitude and expressing killed within ranicchia in a corner. The CRF is inhibited by the increased glucocorticoids, occurs in parts of parvocellulari paraventricular nucleus of the hypothalamus, a number of cells in the hypothalamus and basal forebrain in regulating the function, you activate the locus coeruleus (limbic system) which produces catecholamines, the neurotransmitter of s. activate the hypothalamus and limbic produce cortisol and adrenaline.

Pathophysiology of adaptive response to stress:

What happens during the application of a stressful stimulus:

* Inhibition of insulin and increased blood glucose, essential for brain exercise and stress;

* Inhibition of inflammatory mediators with tissue damage;

* Inhibition of immune response and effect of these mediators with stressful interevento of cytokines, interleukins, natural killer etc..

* Inhibition of aldosterone with excessive fluid retention;

* Inhibition of neuropeptides (CRF, ACTH, beta-endorphins, etc.) that attempts to end the neurochemical cascade to avoid the existence of a disease neuropsychic;

After the stimulus appears stressful symptoms with neurovegetative symptoms: tachycardia, sweating, flushing hot and cold, which may disappear after a few hours or days, others may arise in the flashbacks. More importatnt is maladaptive symptoms of post-traumatic (ie after the stressful event), which tends to persist after distrubo months, usually not more than 6 mesi.Es. raped women, war veterans, subjects after the divorce, bereavement etc.. The syndrome known as "burnout" or exhausted candle typically occur in managers, professionals for whom it is necessary in considerable expenditure of energy and is characterized by insomnia, easy fatigability, depressed mood, reduced frustration, drug abuse. The Chronic Fatigue Syndrome is a recent discovery and is characterized by severe fatigue, physical and mental part of central origin and in the periphery. It is interesting to emphasize that there is a relationship between maladaptive syndrome and abuse of psychoactive substances. Adolescence there is a difficulty in coping that adaptation to new situation occurring in their bodies during adolescence leading to distress and depression, aggressive children become unpopular in the group and this is accompanied by hyperactivity, the tendency to a drop in self-esteem, depression, isolation and led to immature and dependent. In these cases there will be a reduction of the enzyme dopamine beta-hydroxylase alterations serotoninenrgico system (thus reducing the release of serotonin and depression), and alpha-adrenergic sensitivity.

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Resulting adjustment disorder which may lead to a depressive episode (mild, medium, severe), which, along with a reduction in mood and concentration, you will reduce energy, neurasthenia, easy fatigue, brain , myalgia, dizziness, headache, muscle-tensive, sleep disturbances. Another disorder is anorexia nervosa, which is accompanied by high cholesterol, hypothalamic hypogonadism, impaired secretion of arginine-vasopressiva. Inhibition of the hypothalamic-pituitary-gonadal axis represents the starting point of a large pathology of reproduction. The CRF presides over the central biochemical response with release of ACTH, beta-endorphins, betalipoproteina, prolactin, simultaneously decreases the secretion of GnRH and thus LH stimulates testosterone (men) and progesterone (female). It follows: amenorrhea in women, premenstrual syndrome, hypercortisolemia, growth hormone hyperandrogenism with ovarian theca.
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