Hormonal Control of Behavior Lecture 10 Chemical Control

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 Diffuse control l widespread control l slower, longer lasting n Diffuse modulatory systems n Neuroendocrine system ~ n

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

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

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

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

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

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

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

Pituitary Gland 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 n magnocellular secretory cells ~

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

Posterior Pituitary: Supraopticohypophyseal Tract

Supraoptic nucleus PVN Posterior Pituitary

Posterior Pituitary: Neurohormones 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 n l Vasopressin ~

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

Antidiuretic Hormone (ADH) AKA: Vasopressin n 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 ~ n

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

SFO Hypothalamus A II PVN & SON LH ADH Thirst Kidneys

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

Anterior Hypothalamus: Hypothalamopituitary Portal System

Anterior Hypothalamus 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 n gonads mammary adrenal thyroid ~

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

Neuron Capillary Beds Portal Vein G

RH G

TH RH TH TH G TH TH

Cortisol Regulation 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 ~ n

Cortisol Regulation 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 ~ n

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

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

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