Behavioral Neuroscience
Yawning Behavior
Evolution of Yawning
Sensory Afferents to Yawn
Gating the Yawn
Yawning Regulating Yawn Gating
Efferent Yawn Output
Neuromuscular Production of Yawns
Integration of Yawn Circuitry and Behavior
norepinephrine (NE)
Oxytocin (OT)
Yawning figures
Yawn Circuitry
end     Acronyms/Abbreviations

VII. Oxytocin (OT, OxT, Oxy) A. Nonapeptide synthesized by the PVN and SON of the hypothalamus 1. NH2 - Cys - Tyr- Ile - Gln - Asn - Cys - Pro - Leu - Gly - COOH |_____S_____S_______| a. cysteine-cysteine disulfide bonds b. Evolutionary precursor = Arginine Vasotocin (AVT) i. NH2-Cys - Tyr- Ile - Gln - Asn - Cys - Pro - Arg - Gly-COOH |_____S_____S_______| 2. PVN magnocellular subnucleus makes mostly OT a. supraoptic magnocellular subnucleus mostly AVP b. pro-OT produced from OXT gene includes neurophysin I (carrier protein) i. cleaved in golgi by peptidylglycine a-amidating monooxygenase (PAM) c. OT transported into dendrites i. retrograde dendritic release is critical to control OT neuron firing patterns (inhibits Glu) 3. OT also synthesized by smaller, parvocellular neurons of the PVN and medial preoptic area (mPOA) 4. OT synthesized by neurons in the BNST and LA (bed nucleus of the stria terminalis) and (lateral amygdala) a. OT fibers project into the brain
B. OT Receptors 1. genterated in terminal regions from the OXTR gene a. OXTR polymorphism (rs53576) occurs in the 3rd intron i. 3 types: GG, AG, AA ii. A-allele carrier Þstress sensitivity social skill / mental health 2. OT-R is a rhodopsin-type (class I) receptor a. functionally homologous to V1 receptors ö DG Þ PKC b. GpÞPLC ÞPIP2 ÞIP3 ÞCa++
C. OT terminals and OT-R are widely distributed throughout the brain & spinal cord 1. Limbic brain: olfactory bulb (OB), tubercle and anterior olfactory nucleus neocortex, and lateral septum ventromedial hypothalamus (VMH)and preoptic area (POA) a. Extended Amygdala & Striatum: LA, CeA, and BNST ventral tegmental areas (VTA), nucleus accumbens (NAc) b. Hippocampal formation: hippocampus, subiculum endopiriform cortex i. act as neurotransmitter or neuromodulator 2. medio-dorsal region of the nucleus of the solitary tract a. regulate autonomic nervous system (PVN Þ NST) 3. OT terminals on neurohemal organ a. secreted by neurohypophysis into capillary of inferior hypophysial vasculature
D. Hormonal Physiology of OT 1. Milk Ejection Reflex, Uterine contraction/Parturition, Orgasm a. neuroendocrine reflexes i. sensory stimulation Þafferent signalÞ PVN Þ OT release Þ bloodstream ii. sensory feedback from nipple / cervix / genetalia b. OT-R found in the smooth muscle of the mammary, uterus, vas deferens, and vestibular gland ducts i. OT-R ® GpÞPLC ÞIP3 ÞCa++/Calmodulin ii. Ca++ release is central to all muscle contraction including smooth muscle c. contraction of smooth muscle i. oxy-tocin (wknx tokocx) Greek for "swift birth"
E. OT stimulates Behavioral Functions 1. Combined result of neuronal, CSF, and humoral OT a. neuromodulatory and hormonal effects are synergistic 2. Fear a. OT Þñ inhibitory amygdalar circuit Þò fear responses b. Nasally administered OT Þò fear in humans i. OT Þñ recognition of fear ii. OT Þò anxiety 3. Learning and Memory i. OT Þò memory retrieval of aversive memory ii. OT Þñ social learning and memory 1) intranasal OT Þñ memory for human faces a) especially happy faces 2) intranasal OT Þñ recognition for positive social cues 4. Trust a. positive social interactions Þñ OT release b. OT Þñ contentment, feelings of calmness and security c. OT Þñ trust in humans i. OT Þò fear of social betrayal ii. intranasal OT Þ share ñ emotional details & significance iii. intranasal OT Þ find faces more trustworthy iv. intranasal OT Þñ generosity v. ñ trust induced by OT is limited in degree 1) intranasal OT also Þñ envy and Schadenfreude vi. intranasal OT Þñ empathy 1) MDMA (ecstasy) may Þñ 5-HT1A Þñ OT activity Þñ feelings of empathy, love, and connection to others d. Autism i. autism is correlated with genomic deletion of OXTR 1) autism Þ aberrant methylation of OXTR ii. patients inhaled OT Þñ appropriate social behavior 1) intranasal OT Þñ emotion recognition 2) OT treatment Þñ interpretation of emotions 3) OT Þñ retention of affective speech iii. OT treatment Þò repetitive behaviors 5. Pair Bonding and Parental Behaviors i. Brain OT released during sexual activity is important for forming monogamous pair bonds 1) similar for females and males ii. intranasal OT Þ men in monogamous relationships Þñ distance between themselves and attractive women 1) not single men iii. non-pair bonding 1) humans and dog [OT] rise minutes after petting iv. OT important for initiation of parental behavior 1) not maintenance 2) OT antagonists after birth Þò maternal behavior 3) Þñ CSF OT Þñ maternal behavior in virgin ewes 6. Sexual and Reproductive a. OT affects social distance between adult males and females i. influences romantic attraction b. OT has important role in Þñ sexual arousal i. [OT] increases throughout sexual arousal ii. OT Þñ lordosis and sexual receptivity iii. ñ CSF OT Þñ spontaneous penile erection 1) OT-R antagonist blocks non-contact erections c. OT may Þñ inhibition of the brain regions associated with behavioral control, fear, and anxiety allowing orgasm to occur d. OT released at orgasm Þñ gentital smooth muscle contraction 7. improved Wound healing a. OT Þò certain [cytokine] Þò inflamation b. ñ OT release Þ faster wound healing i. + social interactions Þñ OT release Þñ healing 8. Stress a. OT protects against stress i. OT Þò stress with a good efficiency 1) OT Þ alleviate mood b. Inhibition of HPA axis i. OT indirectly inhibits release of ACTH 1) functional antagonist of AVP? ii. OT indirectly ihibits release of F (cortisol) c. Stress causes relapse, but OT Þò development of drug tolerance 1) OT reduces withdrawal symptoms 9. OT Þñ autonomic sympathetic activity a. parvocellular PVN OT directly connects to NST neurons i. NE and Epi regulates OT-NST synapse number ii. OT-R also found in T1-T4 spinal cord b. sympathetic outflow is regulated through a combination of PVN glutamate, OT, AVP and CRF

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