Serum levels of gonadotropins and gonadal steroids, including testosterone, during the menstrual cycle of the chimpanzee (Pan troglodytes)

Abstract

The objective of this study was to expand the data on menstrual cycle serum hormone patterns in female common chimpanzees, both in terms of the number of cycles analyzed and by the addition of data on testosterone levels. Samples were obtained from 11 unanesthetized animals trained for conscious blood withdrawal. LH, FSH, 176-estradiol (E21, progesterone (PI, and testosterone (T) were measured by radioimmunoassay, genital swelling was recorded, and menstrual blood was noted. Concurrent midcycle elevations in LH and FSH and luteal phase elevations in progesterone suggested that the cycles were ovulatory. Detumescence of genital swelling occurred about 3 days after the midcycle LH peak, 1 day after the luteal phase nadir in Ex, and 1 day after P levels exceeded 5 ng/ml. These relationships provide further support for the use of genital swelling in monitoring progress of the menstrual cycle. The hormone patterns in the chimpanzees closely resembled those of the human females, but E2 and T levels were higher. The levels of Ex and T were higher and the midcycle elevation in T was broader in the chimpanzee than in gorillas and orangutans. This is of interest because E2 and T are implicated in the regulation of mating, and chimpanzees mate over a greater portion of the cycle than the other apes. These data indicate the need for further study of hormonal contributions to the different patterns of mating in the great apes. They also support the use of the female common chimpanzee as a model for the human female in endocrine studies of the menstrual cycle.

Menopause occurs late in life in the captive chimpanzee (Pan troglodytes)

“…The present results refute this claim by revealing that swelling cycles occurred in all eight of the old chimpanzees that ovulated but did not occur in the single old animal that did not ovulate. Indeed, anogenital swelling has an underlying physiology precisely regulated by fluctuations in ovarian steroids (Dahl et al 1991;Deschner et al 2004;Emery Thompson 2005;Graham et al 1972;McArthur et al 1981;Nadler et al 1985). This high degree of association between anogenital swelling and ovulation reinforces our previous conclusion that ovulation in chimpanzees continues into advanced old age.…”

Ovarian hormone concentrations and genital swelling patterns in female chimpanzees with Norplant implants

“…The LH surge and ovulation occur on the last 1-2 days of maximal swelling [Elder, 1938;Graham et al, 1972]. Regression of the genital swelling is associated with decreasing levels of estrogen and increasing lev-els of progesterone [Graham et al, 1972;McArthur et al, 1981;Nadler et al, 1985]. A second estrogen peak occurs during the luteal phase of the cycle concurrent with the peak in progesterone.…”

“…The menstrual cycle can be monitored by two external features: genital swelling and menses [Elder and Yerkes, 1936;Graham et al, 1972;Nadler et al, 1985]. The genital swelling, which encompasses the labia and perianal region, results from an accumulation of interstitial fluid [Elder and Yerkes, 1936] and fluctuates in size and turgidity in response to changing levels of ovarian hormones [Allen et al, 1936;Graham et al, 1972;Nadler et al, 1985].…”

“…Social behavior is correlated with the presence of a female with genital swelling [Wallis, 1982[Wallis, , 1992Bloomsmith et al, 1991;Shefferly and Fritz, 1992], and genital swelling is under the influence of ovarian hormone secretion [Allen et al, 1936;Graham et al, 1972;Nadler et al, 1985]. The dilemma facing managers of captive chimpanzees is determining which method of contraception will temporarily prevent reproduction in select individuals while, at the same time, not interfere with the normal social behavior of the group.…”

Sexual attractiveness: a comparative approach of morphological, behavioral neurophysiological signaling in women and nonhuman primate females

“…Moue than fouty yeaus ago, Dixson et al (1973) uepouted not only a peui-ovulatouy incuease of estuadiol fou puimates, but a similau peak of the anduogen testosteuone as well. Lateu, Nadleu et al (1985) weue able to show an association of estuadiol and testosteuone concentuations duuing the mid-cycle phase and maximum swelling size in the common chimpanzee. Moueoveu, mid-cycle estuadiol and testosteuone peaks of chimpanzees aue compauable to women (Mouuis et al, 1987).…”