Comparative aspects of oxytocin in baboon (Papio hamadryus anubis) and human corpora lutea

In spite of the importance of the corpus luteum in human reproduction,little is known about its formation after ovulation and duringregression in the absence of conception. This is largely dueto constraints on the availability of normal human tissue: thereforean appropriate model which could be studied and provide informationapplicable to the human was sought. The baboon (Papio), a non-humanprimate, has been determined to be one such model. Thus, inthe past several years our studies have examined the role ofluteal peptides in corpus luteum function, and, when possible,we have attempted to examine corpora lutea from the human andbaboon in parallel. Although a milk-ejection factor was recognizedto be present in luteal tissue in 1910 (Ott and Scott, Proc.Soc. Exp. Biol. Med., Vol. 8, p 49), the role of oxytocin inluteal physiology has not been easy to ascertain. This is inpart due to the methodologies employed to assess its role. Ourstudies summarized below suggest that oxytocin does not directlyaffect luteal steroidogenesis, but that it may play a role incell to cell communication involving the expression of the gapjunction proteins, the connexins. In view of the fact that oxytocin,its receptor, gap junctions and associated proteins are notunique to the human and non-human primates, the model of lutealdevelopment and demise proposed may be applicable to most species.