PSYC304 Lecture 07 - Endocrine PDF

PSYC304: Introduction to hormones Jay Hosking, PhD 1 Lecture outline Principles of hormones Hormone types and receptor types The hypothalamus and pituitary gland Notable glands Intro to hormones in behaviour...

PSYC304: Introduction to hormones Jay Hosking, PhD 1 Lecture outline Principles of hormones Hormone types and receptor types The hypothalamus and pituitary gland Notable glands Intro to hormones in behaviour 2  Learning objectives 1. Describe the methods, results, and implications of the first study of hormones. 2. Differentiate the following: exocrine vs. endocrine; endocrine vs. neurocrine vs. autocrine vs. paracrine, pheromone vs. allomone. 3. Describe the principles of hormone function, and note how they differ from neurotransmitter function. 4. Describe the role of the hypothalamus in controlling the endocrine system. What is a neuroendocrine cell? 5. Describe the three basic hormone types, including their size and plasma membrane permeability. 6. Describe hormone receptor types, including linking them to the hormone types. Be sure to appreciate their time course and effects. 7. Describe numerous methods for studying hormones and their receptors, including what each methodology brings that is different or valuable. 8. Describe the anatomy of the pituitary gland, including how that anatomy relates to function. Be sure to differentiate what hormones are released from what components of the pituitary. 9. Describe the pathway of transmission from hypothalamus to target cells, including all intermediary hormones. 10. Describe the following glands, including the hormones they release, and the function of these hormones: the adrenal gland, the thyroid gland, the pineal gland, the gonads. 11. Identify mechanisms through which oxytocin and vasopressin can influence behaviour, including multiple approaches to studying those hormones. 12. Are pheromones relevant to the human experience? Justify your answer with evidence. 13. Describe the dual pathways through which stress activates the adrenal gland. Do stress hormones mediate behaviour? 3 The “first” experiment on hormones: Berthold 1849 Loss of function experiment Restoration of function with native or donor testes Did not require innervation Organizational (appearance) and activational (behavioural) effects Testes make a “secretory blood-borne chemical” 4  Many cells secrete chemicals (1) “Hormone” is quite a catch-all Released primarily by glands (but also other tissues) Released primarily into the bloodstream (but also locally) Released primarily by animals (but also plants?) Exocrine vs. endocrine glands Endocrine glands release hormones 5  Many cells secrete chemicals (2) Neurocrine Endocrine Autocrine Paracrine Pheromone Allomone 6  Principles of hormone function Slow-acting, gradual effects Behaviour changes in intensity/probability rather than polarity Behaviour and hormone release are reciprocal Multiplicity of action Secretion is often pulsatile and rhythmic Hormones can interact Hormones need receptors! (cf. neurotransmitters) 7 The hypothalamus and neuroendocrine cells Hypothalamus (HTh): junction between NS and endocrine system HTh contains neuroendocrine cells, aka neurosecretory cells Some hormones are also neurotransmitters! 8  Hormone types Peptide Amine Steroid 9  Hormone receptor types At the membrane i.e. GPCRs faster Intracellular usually near nucleus i.e. transcription factor slower Note: steroid hormones can have GPCRs, too! 10  Methods in measuring hormones and receptors Radioimmunoassay Autoradiography Immunohistochemistry/immunocytochemistry In situ hybridization 11  Negative feedback mechanisms Happen at every conceivable level 12  The pituitary gland The other side of the NS/endocrine intersection Connected via infundibulum, aka pit. stalk Anterior and posterior divisions 13  The posterior pituitary HTh has neuroendocrine cells in paraventricular and supraoptic nuclei Axons travel down infundibulum to posterior pituitary These HTh axons terminate on capillaries These axons release oxytocin and vasopressin/anti-diuretic hormone (ADH) into blood Oxytocin: stimulate uterine contractions in pregnancy; milk letdown reflex ADH: conservation of water; blood vessel constriction Alcohol inhibits L-type calcium channels, which inhibits ADH release (effect?) 14  The anterior pituitary HTh neuroendocrine cells terminate at median eminence HTh release releasing hormones Releasing hormones carried (only a few mm) via hypophyseal portal veins Anterior pituitary has its own hormone-producing cells When releasing hormones arrive, anterior pituitary cells release tropic hormones Tropic hormones travel to glands and cause further hormone release The common motif: Releasing hormones (HTh) à tropic hormones (anterior pituitary gland) à hormones (gland) à target 15  Hormones of the anterior pituitary Six main ones (again, these are tropic hormones): 16  Notable glands (1): the adrenal gland Adrenal cortex vs. adrenal medulla Different inputs to cortex (anterior pituitary) vs. medulla (ANS) Adrenal cortex releases steroid hormones: Glucocorticoids (e.g. cortisol) Mineralocorticoids (e.g. aldosterone) Sex steroids (e.g. androstenedione) Synthesized on demand via ACTH Adrenal medulla releases amine hormones: Epinephrine Norepinephrine 17  Notable glands (2): the thyroid gland Releases thyroid hormones: thyroxine, triiodothyronine These are amines but act like steroids (meaning?) Generally, regulate growth and metabolism Also has a general activating effect on NS Only substance in body that needs iodine Hypothyroidism Thyroid also releases calcitonin 18  Notable glands (3): the pineal gland aka Your third eye! (Not really) The seat of the soul? (No) Releases melatonin Melatonin released at night Inputs: from sympathetic NS! 19  Notable glands (4): the gonads Two compartments in male and female gonads: one for sex hormone production, one for gametes production GnRH and/or GnIH (HTh) à FSH & LH (ant. pit.) à gonads And kisspeptin (peptide nt) stimulates GnRH Testes: Sertoli cells (sperm) Leydig cells (androgens, e.g. testosterone) Ovaries: Ova (mature gametes) Steroid hormones (progestins, e.g. progesterone, and estrogens, e.g. estradiol) 20  Hormones in behaviour? Prairie vole Yes, BUT with notable limitations in humans i.e. Cortex often supersedes many older controls for behaviour The most vigorous responses are observed in animal models And the converse is true: behaviour influences hormones e.g. Psychosocial dwarfism Meadow vole e.g. Oxytocin and vasopressin/ADH Exogenous oxytocin in rats Oxytocin knock-outs in mice Oxytocin & vasopressin receptors: ventral pallidum (VP) Prairie voles vs. meadow voles 21  The “love molecule”? The “cuddle chemical”? The promise of oxytocin is alluring, but the data show (as per usual) that the story is more complicated than we initially thought 22  Oxytocin increases in-group bias De Dreu et al. 2011 23 Oxytocin increases propensity for revenge! Han et al. 2020 24  How about pheromones? Do they mediate behaviour? The power of pseudoscience (and marketing) 25  How about pheromones? Do they mediate behaviour? Non-human animals: yes, definitely, via the vomeronasal organ (VNO) Humans: Not so much. Our VNO and its related genes are basically non-existent Putative human pheromone effects (McClintock effect, men’s sweat) often don’t replicate 26 McClintock & Martha 1971  How about stress hormones? Do they mediate behaviour? All animals (including humans): yes, definitely BUT part of stress response is central (i.e. in the brain) Dual pathways HPA axis Sympathetic NS 27  How about stress hormones? Do they mediate behaviour? All animals (including humans): yes, definitely BUT part of stress response is central (i.e. in the brain) Schacter & Singer 1962: stress response is interpreted Experiment to test “new vitamin” (epinephrine) Schacter & Singer’s Two-factor theory 28