SOCIAL BEHAVIOR WHAT IS MONOGAMY? Social monogamy – preference for a specific partner (sexual exclusivity not essential) Demonstrated by physical proximity Monogamy also often associated with paternal care 1 FIG 12.13 OXYTOCIN AND VASOPRESSIN NEUROBIOLOGY Oxytocin/ OF PAIR-BONDING (“LOVE”) vasopressin/ review Why y were oxytocin y and vasopressin p originally identified as bonding hormones? Species differences…where are monogamous and polygynous species different? 2 Empty Cage Tethered Partner Animal Tethered Stranger Animal Paraventricular nucleus Supraoptic nucleus AVP is also produced in: Suprachiasmatic nucleus (In males only): Medial amygdala Bed nucleus of the stria terminalis 3 OXYTOCIN AND VASOPRESSIN RECEPTORS OT has one receptor throughout the body, expressed in many tissues including brain, uterus, male reproductive tract, mammary glands, l d etc. AVP has three receptor subtypes: V1a, V1b, V2 4 COOL AVP EXPERIMENTS 1) Injection of prairie vole V1a receptor genes into mice 2) Up- and down- regulation of V1a receptors in voles via viral vectors 3) Genetic studies of AVP receptor promoter regions 5 VASOPRESSIN RECEPTOR VARIATION (YOUNG, HAMMOCK) Nair and Young, 2006 Nair and Young, 2006 Nair and Young, 2006 6 BOTH OT AND AVP ARE INVOLVED IN SOCIAL RECOGNITION AND MEMORY OT knockout mice do not “remember” other individuals. Long history of studying AVP and social behavior (David DeWied). BOTH OT AND AVP CAN INDUCE A PAIR- BOND IN BOTH SEXES Cho et al. 1999 – treatments given ICV Administration of OT or AVP could induce a pairbond in either sex Blocking OT or AVP could eliminate a pair-bond in either sex STRESS AND PAIR-BONDING Formation of a pair-bond also affected by stress Females that receive additional corticosterone take longer to pair-bond; remove their adrenal gland and they pairpair bond faster Males that receive additional corticosterone or CRH take a shorter time to pair-bond; remove their adrenal gland and they pair-bond slower 7 REWARD COMPONENTS Mating induces dopamine release in both males and females Dopamine has multiple receptors (D1, D2, D3, etc.) Blocking Bl ki th these receptors t non-selectively l ti l reduces pair-bonding (haloperidol) A non-selective DA agonist (apomorphine) injected into the Nacc induced pair-bonding (but not when injected into the striatum) note: at low doses but NOT high doses High doses probably activating D1 in addition to D2 D2-type specific receptor agonist, quinpirole, q p induces partner p preferences p Blockade of D1 specifically does not inhibit partner preferences Activation of D1 prevents quinpiroleinduced preferences Overall message: D2 activation = partner preference D1 activation = no partner preference 8 Lateral septum; social memory Olfactory system MeA VTA, Nucleus accumbens shell Ventral pallidum MdThal Colocalization of V1a receptors with dopamine D2 receptors 1) Both oxytocin and vasopressin are necessary in both sexes. 2) However, vasopressin may be more “important” in males and oxytocin is more “important” important in females. females 3) Dopamine is also a critical component of pair-bonding in both sexes. 4) Pair-bonding can be modulated by stress hormones (i.e. corticotropin-releasing hormone). Photo: A. Williams/Sacramento Bee 9 TITI MONKEYS Monogamous Strong primate pair-bond between male and female carry infants over 90% of time When separated, pair-mates have increased cortisol levels When infant is separated, neither father nor mother has elevated cortisol Infant has elevated cortisol when separated from father but not from mother Males Early environment can affect the ability to form social bonds. 10 MODELS OF EFFECTS OXYTOCIN SYSTEMS Early Handling OF EARLY EXPERIENCE Parental Stimulation O t i Oxytocin ON Social Behavior Anxiety O t i Oxytocin Based on models by Levine, Denenberg, Meaney, Champagne, Francis, Pedersen, Boccia, etc. MAN1 MAN0 11 HANDLING EFFECTS ON MALE ALLOPARENTAL CARE Bales et al., Developmental Psychobiology, PARTNER PREFERENCE TEST Behaviors Scored Location Empty Contact Partner Stranger Empty cage Partner’s cage St Stranger’s ’ cage No contact Partner contact Stranger contact 12 HANDLING EFFECTS ON FEMALE PAIR-BONDING Bales et al., Developmental Psychobiology, HANDLING EFFECTS ON ANXIETY Bales et al., Developmental Psychobiology, 13 FEMALE OT MALE OT RECEPTOR BINDING RECEPTOR BINDING 14 OT PRODUCTION IN THE SON 15 PHARMACOLOGICAL MANIPULATION OXYTOCIN - METHODS OF On day 1 of life, infants receive an injection of either: 1) Oxytocin (OT) 2) Oxytocin antagonist (OTA) 3) Saline (SAL) 4) They are handled only (HAN) Tested: parental care, partner preference, plus-maze, and intrasexual aggression EXPOSURE TO OTA REDUCES ALLOPARENTAL CARE IN MALES Proportion Displayin ng Behavior 0.8 0.7 a Males - Day 21 a 0.6 0.5 Parental 0.4 b z Attack 0.3 0.2 y,z 0.1 y 0 CTL (n = 34) OT (n = 18) OTA (n = 17) Bales et al., Developmental Psychobiology, OT SHOWS A DOSE-RESPONSE IN FEMALES 0.07 Proportion time spen nt in contact Partner 0.06 n = 26 b n = 14 0.05 n = 15 n = 14 0.04 0.03 n = 12 Stranger a,b a a * 0.02 a 0.01 0 Saline 1mg/kg 2mg/kg 4mg/kg 8mg/kg Bales et al., Hormones and Behavior, 16 MALE DOSE-RESPONSE 0.16 Partner Stranger Proportion time in c contact 0.14 0.12 01 0.1 0.08 * 0.06 * 0.04 0.02 0 Saline V1A600RECEPTORS 1mg/kg 2mg/kg 4mg/kg CHANGE IN MALES OT OTA Males Change from litte er CTL (DPM) 400 * 200 0 -200 * * -400 -600 * -800 VP MeA MPOA BNST LS CgCtx MdThal Bales et al., Neuroscience 2007 INTRANASAL OXYTOCIN Available for $29.95 on Amazon Chronic intranasal OT (not liquid trust brand) is in clinical trials for use with kids with autism No previous animal testing for longterm effects 17 18