STRESS & THE ENDOCRINE SYSTEM
2 primary stress hormones:
- Cortisol
- Epinephrine
à act in concert with all the peripheral components of the acute response to stress
à play key roles in how the central nervous system is influenced in reaction to stress
responses and they ultimately shape our long-term responsivity to stress
OVERVIEW OF STRESS ENDOCRINE REGULATION
One output from the hypothalamus and brainstem that shape bodily stress responses is to
the endocrine system:
- Controls over cortisol and epinephrine that participate in stress reactions
- Cortisol and epinephrine act over time to bind together actions of separate organs
and systems to coordinate widespread elements of the peripheral stress response
Feedforward processes:
- Determine the magnitude and patterning of autonomic and endocrine activity that
affects the periphery
- Arise from the frontal-limbic interactions (from hypothalamus & brainstem)
- Activational and regulatory messages back upstream to higher brain regions
Feedback processes associated with the stress endocrine system regulate:
- Short-term secretion of stress hormones themselves
- Gene expression in frontal-limbic areas that modulate long-term stress responsivity
- Shaping of memories for emotionally significant events and consequently altered
appraisal processes
ACTIVATION OF STRESS ENDOCRINE SECRETION AND THE CENTRAL CORTICOTROPIN-
RELEASING FACTOR SYSTEM
During normal periods of activity cortisol follows a daily cycle:
- Cortisol release peaks just after awakening
- Declines through the waking hours
- Moderate rise about lunchtime in response to food intake
- Further decline through evening hours
- Daily low point: in the early morning hours
1
, CORTISOL REGULATION
Cortisol’s daily cycle is driven by signals from the body’s clock in the suprachiasmatic nucleus
of the hypothalamus:
1. During the morning cortisol surge: suprachiasmatic neurons activate the
paraventricular nucleus of the hypothalamus (PVN)
2. Causing a rise in the release of corticotropin-releasing factor (CRF) from the
hypothalamus to the anterior pituitary
3. Resulting in production of ACTH and beta-endorphin
4. ACTH circulation to the adrenal cortex increases cortisol synthesis there and elevates
the release of cortisol into the systemic circulation
5. Cortisol secretion is regulated by negative feedback:
o To the pituitary gland, via the systemic circulation
o And to the hypothalamus and hippocampus by way of the cerebrospinal fluid
of the ventricles
6. Reduce the secretion of both CRF and ACTH
STRESS EFFECTS AND THE CENTRAL CRF SYSTEM
CRF system = corticotropin-releasing factor system
= specialized systems of neurons that synthesize CRF & that act together to
integrate the CNS response to stress
CRF:
- Hypothalamic neuropeptide responsible for regulation of the HPAC
- Also acts as a peptide transmitter in a widespread system of neurons that appear to
integrate sensory information with states of emotion and the behaviors and to shape
autonomic and hormonal responses that accompany these emotions
Greatest accumulation of neurons with CRF-producing cell bodies: in the PVN of the
hypothalamus à project to:
- Median eminence of the hypothalamus to stimulate the pituitary
(à median eminence = poort voor release v hypothalamische hormonen)
- Brainstem and spinal cord where they can modulate autonomic outflow
The primary integration of output signals to the cardiovascular and endocrine components
of the fight-flight response is through CRF cells of the PVN that project to the median
eminence and the brainstem
2
2 primary stress hormones:
- Cortisol
- Epinephrine
à act in concert with all the peripheral components of the acute response to stress
à play key roles in how the central nervous system is influenced in reaction to stress
responses and they ultimately shape our long-term responsivity to stress
OVERVIEW OF STRESS ENDOCRINE REGULATION
One output from the hypothalamus and brainstem that shape bodily stress responses is to
the endocrine system:
- Controls over cortisol and epinephrine that participate in stress reactions
- Cortisol and epinephrine act over time to bind together actions of separate organs
and systems to coordinate widespread elements of the peripheral stress response
Feedforward processes:
- Determine the magnitude and patterning of autonomic and endocrine activity that
affects the periphery
- Arise from the frontal-limbic interactions (from hypothalamus & brainstem)
- Activational and regulatory messages back upstream to higher brain regions
Feedback processes associated with the stress endocrine system regulate:
- Short-term secretion of stress hormones themselves
- Gene expression in frontal-limbic areas that modulate long-term stress responsivity
- Shaping of memories for emotionally significant events and consequently altered
appraisal processes
ACTIVATION OF STRESS ENDOCRINE SECRETION AND THE CENTRAL CORTICOTROPIN-
RELEASING FACTOR SYSTEM
During normal periods of activity cortisol follows a daily cycle:
- Cortisol release peaks just after awakening
- Declines through the waking hours
- Moderate rise about lunchtime in response to food intake
- Further decline through evening hours
- Daily low point: in the early morning hours
1
, CORTISOL REGULATION
Cortisol’s daily cycle is driven by signals from the body’s clock in the suprachiasmatic nucleus
of the hypothalamus:
1. During the morning cortisol surge: suprachiasmatic neurons activate the
paraventricular nucleus of the hypothalamus (PVN)
2. Causing a rise in the release of corticotropin-releasing factor (CRF) from the
hypothalamus to the anterior pituitary
3. Resulting in production of ACTH and beta-endorphin
4. ACTH circulation to the adrenal cortex increases cortisol synthesis there and elevates
the release of cortisol into the systemic circulation
5. Cortisol secretion is regulated by negative feedback:
o To the pituitary gland, via the systemic circulation
o And to the hypothalamus and hippocampus by way of the cerebrospinal fluid
of the ventricles
6. Reduce the secretion of both CRF and ACTH
STRESS EFFECTS AND THE CENTRAL CRF SYSTEM
CRF system = corticotropin-releasing factor system
= specialized systems of neurons that synthesize CRF & that act together to
integrate the CNS response to stress
CRF:
- Hypothalamic neuropeptide responsible for regulation of the HPAC
- Also acts as a peptide transmitter in a widespread system of neurons that appear to
integrate sensory information with states of emotion and the behaviors and to shape
autonomic and hormonal responses that accompany these emotions
Greatest accumulation of neurons with CRF-producing cell bodies: in the PVN of the
hypothalamus à project to:
- Median eminence of the hypothalamus to stimulate the pituitary
(à median eminence = poort voor release v hypothalamische hormonen)
- Brainstem and spinal cord where they can modulate autonomic outflow
The primary integration of output signals to the cardiovascular and endocrine components
of the fight-flight response is through CRF cells of the PVN that project to the median
eminence and the brainstem
2
