Oxytocin
Oxytocin (Oxt) is a peptide hormone and neuropeptide. Oxytocin is normally produced by the paraventricular nucleus of the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, sexual reproduction, childbirth, and the period after childbirth. Oxytocin is released into the bloodstream as a hormone in response to stretching of the cervix and uterus during labor and with stimulation of the nipples from breastfeeding. This helps with birth, bonding with the baby, and milk production. Oxytocin was discovered by Henry Dale in 1906. Its molecular structure was determined in 1952. Oxytocin is also used as a medication to facilitate childbirth.
Oxytocin
While the structure of oxytocin is highly conserved in placental mammals, a novel structure of oxytocin was recently reported in marmosets, tamarins, and other new world primates. Genomic sequencing of the gene for oxytocin revealed a single in-frame mutation (thymine for cytosine) which results in a single amino acid substitution at the 8-position (proline for leucine). Since this original Lee "et al." paper, two other laboratories have confirmed Pro8-OT and documented additional oxytocin structural variants in this primate taxon. Vargas-Pinilla "et al." sequenced the coding regions of the OXT gene in other genera in new world primates and identified the following variants in addition to Leu8- and Pro8-OT: Ala8-OT, Thr8-OT, and Val3/Pro8-OT. Ren "et al." identified a variant further, Phe2-OT in howler monkeys.