Hormonal Control of Behavior Lecture 10

Chemical Control of Brain n Point-to-point control l closed-circuit l synapse l fast, short-lived, local ~

Chemical Control of Brain n Diffuse control l widespread control l slower, longer lasting n Diffuse modulatory systems n Neuroendocrine system ~

Hormones & Behavior? n Responses to a changing environment detect stimulus > make response n Effectors l muscles l glands n Autonomic N.S. l Homeostasis ~

2 Types of Glands n Exocrine l ducts l sweat, tears, etc. n Endocrine l ductless l hormones l released into blood ~

Neurohormones n Interact with nervous system n Chemical message l Neurotransmitters (NTs) l Hormones l Pheromones n What’s the difference? ~

Neurohormones n Similarities l chemical messengers l act at receptors l influence behavior n Differences l medium l distance traveled l time course ~

Neurohormone Properties n Neurons release molecules into blood l Long distances l Slower l Longer lasting effects l Widespread ~

Function n Developmental l sex differentiation l testosterone, estradiol n Regulatory l Insulin, CCK, etc. l Vasopressin, Oxytocin ~

Types of Neurohormones n Amino acid-derived hormones l e.g. epinephrine released from adrenal medulla n Protein & Peptide Hormones l Bind to membrane receptors l Activate the 2nd messenger system ~

Types of Neurohormones n Steroid Hormones l Derived from cholesterol l Soluble in lipids l Bind to cytoplasmic receptors regulates gene expression l e.g. sex hormones ~

Neuroendocrine System n Brain n Hypothalamus l Releasing Hormones n Pituitary gland l Anterior: tropic hormones l Posterior: neurohormones n Glands - Hormones ~

Pituitary Gland n 2 parts l different developmental origins n Anterior pituitary (adenohypophysis) l no axons from hypothalamus l parvocellular neurosecretory cells l portal system n Posterior pituitary (neurohypophysis) l axons from hypothalamus magnocellular secretory cells ~

Anterior Pituitary- Adenohypophysis Posterior Pituitary- Neurohypophysis Hypothalamus Pituitary Stalk Pituitary hypophysis G

Posterior Pituitary: Supraopticohypophyseal Tract

Supraoptic nucleus PVN Posterior Pituitary

Posterior Pituitary: Neurohormones n Magnocellular neurosecretory cells l Supraoptic & Paraventricular Nuclei n Neurons fire ---> Neurohormones released l Transported down axons l to posterior pituitary n Peptide Neurohormones l Oxytocin l Vasopressin ~

Oxytocin n Induces uterine contractions l child birth l orgasm during sex n Triggers lactation l “letdown reflex” l triggered by touch, sight, sound ~

Antidiuretic Hormone (ADH) n AKA: Vasopressin Responds to  blood pressure l Induces vasoconstriction l Promotes water retention n Kidney: Renin release l Angiotensin I ---> Angiotensin II l to kidneys & subfornical organ ~

Subfornical Organ n Subfornical organ - SFO l Dorsal 3d ventricle l lacks blood-brain barrier l A II receptors n Output to l Supraoptic & paraventricular nuclei ADH release l lateral hypothalamus (LH) thirst ---> drinking behavior ~

SFO Thirst PVN & SON LH Hypothalamus Kidneys ADH A II

ADH (Vasopressin) n Alcohol suppresses ADH release n Damage ---> diabetes insipidus l Symptoms copius urination intense thirst ~

Anterior Hypothalamus: Hypothalamopituitary Portal System

Anterior Hypothalamus n Primordial tissue from roof of mouth n No axons from hypothalamus l Parvocellular neurosecretory cells l Releasing hormones l triggers release of tropic hormones n Tropic hormones ---> various glands gonads adrenal mammary thyroid ~

Hypothalamopituitary Portal System n Portal Systems l Capillary beds l Connected by a vein e.g. hepatic portal vein n Hypothalamus ---> Anterior Pituitary ~

G Capillary Beds Portal Vein Neuron

G RH

G TH

Cortisol Regulation n Adrenal glands l medulla: NE & E l cortex: cortisol n Regulation of cortisol l steroid l fight/flight & immunosuppression l stress response n Receptors widely distributed ~

Cortisol Regulation n Hypothalamus l Corticotropin-releasing hormone (CRH) n Anterior pituitary l Adrenocorticotropin (ACTH) n Adrenal cortex l Cortisol n Negative feedback to hypothalamus l cortisol inhibits own release ~

Sex Hormones n Hypothalamus l Gonadotropin-releasing hormone - GRH l isolated from pig hypothalami n Anterior Pituitary - l Gonadotropins Follicle stimulating hormone - FSH Lutenizing hormone - LH ~

Gonadotropins: Target Cells n Gonads n Testes - l Androgens -Testosterone n Ovaries - l Estrogens l Estradiol and Progesterone ~

Gonadotropin Release Patterns n Sex differences l FSH & LH both sexes n Males ----> steady n Females? cyclical n Transplant male pituitary into female? ~