STRESS Stress (ambiguous term): –The event: A threat (real or implied) to homeostasis (often called a stressor) –The response: the physiological response to the threat –The condition: the physiological state that results Stressors –Physiological stress –Physical stress –Emotional stress

Phases of the stress response –Time frame of hormonal response Modulation of the Stress Response Stress in Humans: How can we cope?

Phases of the stress response Alarm Phase Resistance Phase Exhaustion Phase

Alarm Phase: Catecholamines: epinephrine and norepineprhine Adrenal Gland Sympathetic Neuron epinephrine Releases norepineprhine onto these tissues

Epinephrine and Stress

Catecholamines--what do they do? –Metabolic: –Cardiovascular: –Respiratory:

Phases of the stress response Alarm Phase Resistance Phase Exhaustion Phase

hypothalamus pituitary adrenal Glucocorticoids (cortisol, corticosterone

Common Diving Petrel near the South Georgia Islands

Pre-storm (n=3) Storm (n=8) Calm (n=8) Time after capture (min) Corticosterone, ng/ml

Kirschbaum et al., 1995 Buske-Kirschbaum et al., 1997 Two Examples from Human Studies Kids Adult men

Effects of Glucocorticoids Increase circulating glucose Suppress the immune system Suppress reproductive behavior Suppress growth Multiple behavioral effects, dependent on species… –e.g. Induce territory abandonment Increase foraging Reduce parental care Emergency Life History Stage

The stress response alarm and resistance Maximizes glucose in the blood Maximizes glucose and oxygen delivery to critical tissues Shuts down non-critical activities (redirects physiology and behavior) –Digestion –Reproduction –Growth

Phases of the stress response Alarm Phase Resistance Phase Exhaustion Phase

High pulse rate, elevated blood pressure Breakdown of protein for gluconeogenesis Hyperglycemia, insulin suppression Decrease reproduction Shut-down digestion Inhibit immune system Artherosclerotic plaques, heart disease, embolisms, strokes Muscle wasting Insulin insensitivity (NIDDM) Infertility, shut-down of reproductive axis Ulcers, irritable bowel syndrome Degeneration of immune tissues Neural degeneration ACUTE RESPONSES TO STRESSCHRONIC STIMULATION

Binding Globulins Do corticosteroid binding globulins change in response to stress? *

Phases of the stress response Alarm Phase –Activated in seconds Resistance Phase –Activated in minutes Exhaustion Phase –Chronic stimulation of Catecholamines and Glucocorticoids

Phases of the stress response –Time frame of hormonal response Modulation of the Stress Response Stress in Humans: How can we cope?

Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Breeding Environment Effect of Parental Responsibility Effect of Body Condition

Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Breeding Environment Effect of Parental Responsibility Effect of Body Condition

Corticosterone and Body Condition fence lizard

Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Breeding Environment Effect of Parental Responsibility Effect of Body Condition

PESASESAWESAREPH Males Females Magnitude ofCorticosterone Increase, ng/ml Pectoral Sandpiper Semipalmated Sandpiper Red Phalarope F M + F MParental care? :

Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Breeding Environment Effect of Parental Responsibility Effect of Body Condition

Breeding Environment

Abert's Towhee summer winter Inca Dove Time after capture (mintues) CORT (ng/ml) summer winter Cactus Wren winter summer Black-throated sparrow BENIGN BREEDING ENVIRONMENT HARSH BREEDING ENVIRONMENT

Modulation of the adrenocortical response to stress Is it always adaptive to respond hormonally to stress? Effect of Breeding Environment Effect of Parental Responsibility Effect of Body Condition