Role of Oxytocin in onset of Maternal Behavior in Ewe
Archita singh, Neha rajawat, Narayni yadav, Mamta mishra and likhita BN
Ph.D Scholar, IVRI; M.V.Sc Scholar, IVRI; Ph.D Scholar, IVRI; Ph.D Scholar, IVRI; M.V.Sc Scholar , IVRI
Introduction:-
Oxytocin is neuropeptide (Octapeptide), produced in the hypothalamus by magnocellular neurons and parvocellular neurons of paraventricular and supraoptic nucleus. It is released into the circulation, in majority through axonic secretion of magnocellular neurons however in brain through dendritic secretion of parvocellular neurons. Peripherally released oxytocin facilitates parturition and milk ejection during nursing and can also reenter brain through RAGE transporter to show CNS effect. Centrally released oxytocin modulate different types of socio-emotional and affiliative behavior, such as anxiety, stress, social behavior, pair bonding, alloparental care, coordination of the onset of maternal nurturing behavior at parturition and mother-infant bonding.. Manifold effects of oxytocin is due to its ability to stimulate or inhibit different subcellular signalling cascade like up and down regulation of genes. It regulates behavior directly and indirectly by modulating status of other neuron and its secretion. Oxytocin-driven modulation happens through regulation of effectors, such as MEF2 , CREB, CRHBP, and many more.
Mechanism through which oxytocin regulates maternal behavior:-
Dopamine is a central neurotransmitter. Dopaminergic neuronal cell bodies originating in the substantia nigra (SN), hypothalamus, ventral tegmental area (VTA), arcuate nucleus and the zona incerta, from which it has widespread projections to the different region of the CNS(Baskerville and Douglas,2010) where oxytocin producing neurons are found. hypothalamic oxytocin cells express dopamine receptors(Baskerville et al.,2009).Oxytocin-sensing receptors are found to be expressed on dopaminergic(DA) neurons (Grinevich et al.,2016).Therefore crosstalk between dopminergic neuron and oxytocin neuron reported to control onset of maternal character.
Stimulation caused by passage of lamb through birth canal, causes release of oxytocin. Released oxytocin to circulation again reaches to olfactory bulb of brain by crossing blood brain barrier (BBB) via RAGE receptor, where dopaminergic neurons are found. Oxytocin binds to oxytocin receptor present on DA neuron , causing release of dopamine. Released dopamine initiates a sensitive period during which ewe identify smell of the lamb as her own called olfactory memory due to formation of new syneptic connection.(Dukes physiology ,edi-12). Such olfactory memory is part of mother-infant bonding in sheep that occurs at birth and can be induced by vagino-cervical stimulation under appropriate steroid condition (Kendrick,2000; Sanchez-Andrade and Kendrick,2009)
Conclusion:-
In conclusion, oxytocin exerts behavior as well as peripheral effect. The behavioral effects of OT are shaped by the plasticity of neuron releasing oytocin and modulation of neurons showing receptor of oxytocin in brain. Therefor oxytocin affects onset of maternal behavior by modulation of dopaminergic neuron.
