An increase in kisspeptin-54 release occurs with the pubertal increase in luteinizing hormone-releasing hormone-1 release in the stalk-median eminence of female rhesus monkeys in vivo.

The G-protein coupled receptor GPR54 and its ligand, KiSS-1-derived peptide kisspeptin-54, appear to play an important role in the mechanism of puberty. This study measures the release of kisspeptin-54 in the stalk-median eminence (S-ME) during puberty and examines its potential role in the pubertal increase in LHRH-1 release in female rhesus monkeys. First, developmental changes in release of kisspeptin-54 and LHRH-1 were assessed in push-pull perfusate samples obtained from the S-ME of prepubertal, early pubertal, and midpubertal female rhesus monkeys. Whereas LHRH-1 levels in 10-min intervals had been measured previously for other experiments, kisspeptin-54 levels in 40-min pooled samples were newly measured by RIA. The results indicate that a significant increase in kisspeptin-54 release occurred in association with the pubertal increase in LHRH-1 release and that a nocturnal increase in kisspeptin-54 release was already observed in prepubertal monkeys and continued through the pubertal period. Second, we measured kisspeptin-54 release in the S-ME of midpubertal monkeys at 10-min intervals using a microdialysis method. Kisspeptin-54 release in the S-ME was clearly pulsatile with an interpulse interval of about 60 min, and approximately 75% of kisspeptin-54 pulses were correlated with LHRH-1 pulses. Finally, the effect of kisspeptin-10 on LHRH-1 release was examined with the microdialysis method. Kisspeptin-10 infusion through a microdialysis probe significantly stimulated LHRH-1 release in a dose-dependent manner. Collectively, the results are consistent with the hypothesis that kisspeptin plays a role in puberty.

Social suppression of female reproductive maturation and infanticidal behavior in cooperatively breeding Mongolian gerbils.

In several cooperatively breeding species, reproductively suppressed, nonbreeding females are attracted to infants and routinely provide alloparental care, while breeding females may attack or kill other females' infants. The mechanisms underlying the transition from alloparental to infanticidal behavior are unknown. In this study, we tested the hypothesis that this transition is associated with cessation of reproductive suppression and onset of ovarian activity in the Mongolian gerbil (Meriones unguiculatus), a cooperatively breeding rodent. Young female gerbils were housed with their natal family (FH), with a female pairmate (PH) or singly (SH). When females were either 11-13 or 16-18 weeks of age, we characterized their behavioral responses to an unfamiliar pup, reproductive development, and plasma progesterone, cortisol, and prolactin concentrations. In both age groups, FH females were significantly less likely to attack pups than PH or SH females and in fact never did so. FH females also had smaller ovaries and uteri, less developed scent glands, and lower progesterone levels, and were more likely to be anovulatory than PH or SH females, especially in the 11- to 13-week-old age group. Prolactin concentrations did not differ with reproductive status but were significantly higher in females that did not attack pups than in those that did. We found no other significant associations, however, between reproductive or endocrine measures and behavioral responses to pups. These results suggest that cohabitation with the natal family inhibits both infanticidal behavior and reproductive maturation in young female gerbils but that these two effects may not be causally related.

Urinary prolactin is correlated with mothering and allo-mothering in squirrel monkeys.

The hormone prolactin is implicated in infant care-giving by parents and allo-parents in a variety of species. Adult female squirrel monkeys (Saimiri spp.) engage in allo-mothering behavior, which includes carrying and nursing infants, but communal care of offspring has not been investigated from an endocrine standpoint in this taxon. We attempted to fill this gap by examining prolactin levels in squirrel monkeys (Saimiri sciureus) as a function of parental responsiveness. Subjects were housed at the National Institutes of Health Animal Center and assays were performed at the Wisconsin National Primate Research Center. To test for the presence of prolactin in squirrel monkey, saliva, blood and saliva were simultaneously collected from anesthetized subjects during routine health examinations. Prolactin was detectable in serum but not in saliva samples. In the core investigation, behavioral data were collected by focal animal sampling on three 1-male multi-female groups, and individually identified urine was collected non-invasively from foil containers underneath group cages on a daily basis throughout the behavioral study. Changes in urinary prolactin over time reflected changes in the reproductive state of a female who was pregnant, gave birth and lactated during the study. Mean urinary prolactin levels in non-lactating females and a male housed with infants in one group were higher than in adults from 2 groups without infants. In the group with infants, mean urinary prolactin levels in adults increased with the amount of infant contact and care-giving. The squirrel monkey may represent a new primate model for investigating the endocrinology of infant care-giving.

Wasting syndrome and disruption of the somatotropic axis in simian immunodeficiency virus-infected macaques with Mycobacterium avium complex infection.

Mycobacterium avium is a common opportunistic infection of patients with acquired immunodeficiency syndrome (AIDS). We used the simian immunodeficiency virus (SIV)-infected rhesus macaque (Macaca mulatta) model to examine whether disseminated M. avium is associated with disruption of the somatotropic axis in AIDS. Macaques were followed prospectively, and body composition was determined by dual-energy x-ray absorption. Serum levels of insulin-like growth factor (IGF)-1, IGF binding protein-3, growth hormone (GH), and somatostatin were measured. SIV-infected macaques inoculated with mycobacteria had significant changes in body composition, perturbations of the somatotropic axis (characterized by increased GH/IGF-1 ratios) (day 0 [2.21] vs. day of death [DOD] [28.06]; P=.015, Mann-Whitney rank sum test), and increased serum somatostatin levels (day 0 [2.00 ng/mL] vs. DOD [8.58 ng/mL]; P=.026, Mann-Whitney rank sum test). These data document alterations in the somatotropic axis secondary to experimental disseminated M. avium infection and suggest that similar changes may contribute to alterations in body composition during AIDS.

Trophoblast differentiation in embryoid bodies derived from human embryonic stem cells.

Trophoblast differentiation and early placental development are essential for the establishment of pregnancy, yet these critical events are not readily investigated in human pregnancy. We used embryoid bodies (EBs) prepared from human embryonic stem (hES) cells as an in vitro model of early human development. The levels of human chorionic gonadotropin (hCG), progesterone, and estradiol-17beta in medium from hES cell-derived EBs grown in suspension culture for 1 wk were higher than unconditioned culture medium or medium from undifferentiated hES cells or spontaneously differentiated hES cell colonies. EBs were explanted into Matrigel (MG) "rafts" and cultured for up to 53 d. During the first 7-10 d of three-dimensional growth in MG, small protrusions appeared on the outer surface of EBs, some of which subsequently extended into multicellular outgrowths. The secretion of hCG, progesterone, and estradiol-17beta began to increase on approximately d 20 of MG culture and remained dramatically elevated over the next 30 d. EBs maintained in suspension culture failed to demonstrate this elevation in hormone secretion. Suspension-cultured and MG-embedded EBs exhibited widespread expression of cytokeratins 7/8, demonstrating extensive epithelial differentiation as well as consistent hCG expression. We propose that hES cell-derived EBs may be a useful model for investigation of human trophoblast differentiation and placental morphogenesis.

Adult cortisol response to immature offspring play in captive squirrel monkeys.

Variable environmental and social conditions influence hypothalamic-pituitary-adrenal activity in captive animals. Socially separated and individually housed animals generally experience increased cortisol secretion compared to animals housed with conspecifics, and social companionship can buffer the stress response when exposed to challenges such as introduction to novel environments. Nevertheless, the presence of conspecifics may also be the cause of stress because social dynamics impact individuals. Squirrel monkeys (Saimiri spp.) readily form same-sex affiliative social relationships, but in captivity, the presence of immature offspring severely disrupts affiliative associations among adults. We examined behavioral and physiological effects of the presence of immature offspring on adults by comparing two groups of adults with immature offspring to an all-adult group. We conducted behavioral observations and collected urine from adult members, and urine was assayed for cortisol at the Wisconsin National Primate Research Center. Adults in groups with immature offspring received an average of 18 play attempts per hour from the offspring, experienced a fivefold decrease in adult affiliation, and showed higher urinary cortisol levels compared to the all-adult group. A principal components analysis showed that adults characterized by receiving play attempts, rejecting play attempts, and lacking affiliative contact with other adults showed the highest mean urinary cortisol levels. Further analyses demonstrated that the persistent play attempts by immature offspring, not the resulting lack of adult huddling, were primarily responsible for the observed increase in urinary cortisol levels. Taken together, these data suggest that the disruptive effect of immature offspring produces a chronic cortisol increase in captive adult squirrel monkeys.

Detection of urinary gonadotropins in callitrichid monkeys with a sensitive immunoassay based upan a unique monoclonal antibody.

A radioimmunological method for measuring urinary luteinizing hormone (LH) and chorionic gonadotropin (CG) excretion in the family Callitrichidae is described. The method uses a monoclonal antibody that will be available in virtually unlimited quantity. Several polyclonal antisera that have been useful for the detection of callitrichid gonadotropins are near depletion. The monoclonal antibody-based RIA provided similar results when compared with the mouse Leydig cell bioassay for LH and a previously validated polyclonal antibody-based RIA. When the monoclonal antibody is used for immunodetection of Saguinus oedipus LH by non-reducing SDS-PAGE, a single entity is recognized that corresponds with the molecular weight range of bioactive LH and appears to be in the normal range for LH in nonhuman primates. LH and CG were detected by the monoclonal antibody-based RIA in urine from representatives of species from all genera of callitrichids. Hormonal profiles of daily urine samples revealed the detection of the preovulatory LH surge by both RIA methods in the cotton-top tamarin (Saguinus Oedipus) and pygmy marmoset (Cebuella pygmea) and the increase CG due to pregnancy in both species. Serial dilutions of midcycle and pregnancy urine from Saguinus, Callithrix, Leontopithecus, and Cebuella exhibited parallelism when compared with our in-house reference standard of rhesus monkey CG. Cultured Saguinus oedipus pituitary cells showed an increased release of LH when challenged by gonadotropin releasing hormone (GnRH) providing further support that the monoclonal antibody-based RIA measures LH in this species. © 1993 Wiley-Liss, Inc.

The secretion of bioactive and immunoreactive follicle-stimulating hormone (FSH) and luteinizing hormone (LH) throughout the menstrual cycle of the rhesus monkey (Macaca mulatta).

The present study provides the first evaluation of related changes in serum levels of bioactive FSH (Bio FSH) and immunoreactive FSH (iFSH), and concurrent dynamics of LH and FSH bioactivity throughout the menstrual cycle of the rhesus monkey. Mean concentrations of Bio FSH were elevated on days 0 and 1 (n = 7; P < 0.05; day 0 = preovulatory LH surge). Data from individual animals revealed that an average (± SEM) of 1.43 ± 0.29 and 2.71 ± 0.61 discrete surges of Bio FSH occurred in each monkey's follicular and luteal phase, respectively. Analysis of the collective data indicated that periods of increased Bio FSH secretory activity spanned days -1 to 1 and 8 to 10 (P < 0.025). Increases in serum Bio FSH and iFSH concentrations were not precisely correlated on a daily basis (38.9%), although 72.2% of the peaks of Bio FSH and iFSH surges occurred within a day of one another. Similarly, only 36.1% of the Bio FSH surges were accompanied by elevations in bioactive LH (Bio LH). A significant rise in Bio LH, but not Bio FSH, occurred on day -1 (P < 0.01). Concentrations of Bio LH, but not Bio FSH, were elevated in the early luteal phase (P < 0.01). The bioactivity/immunoactivity ratios (Bio/I) of LH and FSH were maximal on the day of the preovulatory surge (P < 0.01). On day -1, LH Bio/I significantly increased (P < 0.05), but no change in FSH Bio/I was detected. The Bio/I of LH, but not FSH, remained elevated in the early luteal phase. In summary: the relative increase in Bio FSH exceeds iFSH during the preovulatory surge. Surges of Bio FSH occur during the follicular and luteal phases which potentially could support follicle selection/maturation. Divergencies between circulating LH and FSH biopotency may reflect a differential regulation of secretion and/or biosynthesis of these hormones. The prolonged early luteal elevation of LH Bio/I is consistent with the idea of a functional role of elevated LH biopotency in the maintenance of the corpus luteum.