Plasma catecholamines in the hypoxaemic fetal rhesus monkey

To assess the response of the sympathoadrenal system of the primate fetus to oxygen deprivation, we measured plasma catecholamines in 8 chronically catheterized fetal rhesus monkeys. A range of fetal hypoxaemia was produced by having the mother inspire 15, 10, or 9% oxygen mixtures while tranquilized with ketamine. Catecholamines from fetal carotid and maternal femoral arteries were measured by radioenzymatic assay. Fetal plasma norepinephrine and epinephrine concentrations increased significantly at all levels of hypoxaemia, but dopamine increased only at very low fetal oxygen tensions. Norepinephrine levels exceeded those of epinephrine and dopamine under all conditions. Relatively more severe hypoxaemia was necessary to elevate concentrations of epinephrine above baseline as compared with norepinephrine. A negative exponential correlation (P less than 0.001) was found between both fetal arterial PO2 and oxygen content and plasma norepinephrine and epinephrine, which was qualitatively similar to that observed previously in the sheep fetus. Maternal catecholamines were found to increase during hypoxaemia as well, but to a lesser degree than in the fetus.     

Testosterone metabolic clearance rate and production rate in the male infant rhesus monkey

The male infant rhesus monkey (Macaca mulatta) undergoes a period of testicular activation similar to that seen in the human infant. Plasma testosterone (T) concentrations rise after birth, reaching levels of about 500 ng/dl at 1-3 mo of age and then fall to approximately 50 ng/dl at 60 mo. The plasma T metabolic clearance rates (MCRT) and production rates (PRT) were measured in two rhesus infants at 1 and 6 mo of age to determine the mechanism of the observed increase in plasma T. While there was little change in the MCRT between 1 and 6 mo, PRT was much higher at 1 mo than at 60 mo of age. These observations are consistent with the hypothesis that the increased plasma testosterone levels in infant rhesus monkeys reflect an increased production of testosterone rather than an altered metabolic disposition of the hormone.     

Plasma cortisol levels and dominance in peer groups of rhesus monkey weanlings.

Determinations of plasma cortisol levels in rhesus monkey infants were obtained before and shortly after they were separated from mother and placed together in small social groups. Differences in pregrouping (baseline) plasma cortisol levels between two infants were good predictors of the direction of the social dominance relationship established between them. This association between lower baseline cortisol values and dominance was not dependent on sex or small differences in age and weight between the infants.     

Cryptococcal dermotropism in the rhesus monkey

An unexpected result was obtained from the intravenous injection ofCryptococcus neoformans into rhesus monkeys. We had sought to develop pulmonary lesions, but instead cutaneous lesions occurred.Each of seven monkeys received five millionCryptococcus neoformans cells intravenously. On the ninth to fifteenth day an acneform cutaneous eruption and nodular sub-cutaneous swellings appeared in all the monkeys and disappeared spontaneously by about the thirtieth day. Biopsies on the ninth day showed free cryptococcal cells with polymorphonuclear response. Biopsy on the twenty-second day showed persistent abscesses with a surrounding shell of giant cells containing shrunken and partially digested cryptococcal organisms. Chest x-rays on the fifteenth day showed no pulmonary lesions. None of the monkeys died spontaneously. When they were sacrificed between the 37th and 102nd day, the lungs were devoid, both grossly and microscopically, or cryptococcal lesions. However, a fulminating cryptococcosis of the right bulbus oculi was found on one monkey and a minute cryptococcal granuloma in the brain of another. Skin testing with cryptococcin was negative before the experimental injection, but became positive at three weeks. Reinjection ofC. neoformans i.v. in one of the monkeys resulted in a second crop of dermal lesions, though of smaller extent and of shorter duration.The 39.5° C temperature of the rhesus monkey may be a factor in the paucity of pulmonary lesions and the development of cutaneous ones.Aided by Grant AI 08454, Department of Health, Education and Welfare, U.S. Public Health Service. Presented at the Annual Meeting of the American Society for Microbiology, Minneapolis, Minn., May 2–7, 1971.     

Histamine and prolactin liberation in the rhesus monkey

The effect of intra venous (i.v.) or intra cerebroventriculaire (i.c.v.) administration of histamine (HA) on plasma prolactin (PRL) levels was investigated in ovariectomized Rhesus Monkeys. Intra venous injection of 50 micrograms/kg HA increased the plasma PRL concentration but icv administration of 10 and 50 micrograms decreased PRL plasma levels. Intra venous injection of 2-thiazolyl-éthylamine, a H1 receptor agonist, rapidly stimulated PRL release (peak PRL concentration at 5 min) suggesting a direct effect on the pituitary. In contrast intra venous administration of the H2 receptor agonist, impromidine, inhibited PRL release at low doses. High doses of impromidine increased PRL concentrations but this effect was delayed (PRL peak values were reached at 20 minutes). Our results show that HA may influence PRL release in the primate via H1 and H2 receptors located at both pituitary and central levels.     

Keratoconus in a rhesus monkey

A 15-year-old female rhesus monkey was observed to have bilaterally thinned and prominently curved corneas. Slit lamp observations, pachymetry, keratometry, and corneoscopy were consistent with a diagnosis of keratoconus, a relatively common corneal dystrophy in humans heretofore not described in a subhuman primate.     

Androgen metabolism in the rhesus monkey.

A mixture of 3H-testosteron (T) and 14C-4-androstene-3, 17-dione (A) was injected intravenously into 2 (I and II) rhesus monkeys (Macaca mulatta). A third monkey (III) was injected with 3H-T only. Urine and bile samples were collected at intervals for 6 hours following the injection. The excretion, conjugation and aglycone metabolites of the steroids injected were studied using these samples. Of the injected dose, animal I (male) excreted 32% 3H and 23% 14C in the bile and 30% 3H and 21% 14C in the urine in 6 hours. Animal II (female), however, had a comparatively higher biliary excretion (66% 3H, 40% 14 C), but a urinary excretion (18% 3H, 13% 14C) comparable to that of animals I and III. The averages in the bile of the 3 animals were: unconjugated compounds 3%, glucosiduronates 78%, sulfates 9%, sulfoglucosiduronates 5% and disulfates 3%; and in urine, 5% unconjugated, 92% glucosiduronates and 3% sulfates. The aglycones obtained following hydrolysis were separated gy chromatography on Lipidex 5000, further purified by thin layer and paper chromatography and identified by co-crystallization. The major matabolites from 3H-T were androsterone and 5beta-androstane-3alpha,17beta-diol, whereas that from 14C-A was androsterone. Other metabolites identified were: etiocholanolone (3beta-hydroxy-5-beta-androstan-17-one); T, epitestosterone (epi-T), (17alpha-hydroxy-4-androsten-3-one); epiandrosterone (3-beta-hydroxy-5alpha-androstan-17-one) and 5alpha-androstane-3alpha, 17beta-diol. The results indicate that while androgen metabolism in the rhesus monkey is similar to that of the baboon and human in conjugate and metabolite formation, the rate of excretion was significantly different, resembline more closely that of the baboon than the human.     

Estrogen dynamics in the female rhesus monkey

The metabolic clearance rates (MCR) and interconversions [( rho]BB) values for estrone (E1) and estradiol (E2) in female rhesus (Macaca mulatta) monkeys on Days 9, 14, and 23 of the menstrual cycle were measured using constant infusions of [3H] estradiol and [14C] estrone. The menstrual cycles in these monkeys were reproduced by using Silastic capsules of E2 and progesterone after bilateral ovariectomy. The serum levels of E2 and progesterone were measured by radioimmunoassay and were similar to those for the intact menstrual cycle. The MCR of E2 on Day 14 (52.8 +/- 6.8 l/day/kg) was significantly greater (p less than 0.05) than that measured on Day 9 (31.1 +/- 3.6 l/day/kg) or Day 23 (35.4 +/- 2.1 l/day/kg). The MCR of E1 was also different (p less than 0.05) on Day 14 (77.6 +/- 14.9 l/day/kg) compared to the values on Days 9 and 23 (50.2 +/- 4.9 and 48.2 +/- 3.9 l/day/kg, respectively. There was no change in percentage of free E2, percentage of albumin-bound E2, or sex hormone-binding globulin levels on those 3 days of the cycle. The interconversions between E2 and E1 were not influenced by the day of the cycle. We conclude that the high levels of E2 occurring at the time of the E2 peak result in increases in the MCRs of both E2 and E1 that are not associated with changes in the pattern of protein-binding or in the activity of the 17 beta-hydroxy steroid dehydrogenase.     

Cholesterol metabolism in rhesus monkey, squirrel monkey, and baboon

The metabolism of cholesterol was studied in baboons, rhesus monkeys, and squirrel monkeys while they were being fed either a low fat, low cholesterol (basal) diet or the basal diet supplemented with saturated fat and cholesterol (atherogenic diet). When the diet was changed from basal to atherogenic, the mean total serum cholesterol concentration increased from 70 to 180 mg/dl in the baboon, from 168 to 283 mg/dl in the squirrel monkey, and from 144 to 608 mg/dl in the rhesus monkey. In animals fed the atherogenic diet, the percentage of dietary cholesterol absorbed was greatest in the rhesus monkey and least in the baboon. The fraction of the total body pool of cholesterol that was derived from the diet was greatest in the squirrel monkey and least in the baboon. The turnover of the body pool of cholesterol was several times faster in the squirrel monkey than in the baboon or the rhesus monkey when either dict was fed. The mean total fecal excretion of endogenous cholesterol and bile acid increased in all species on transition to the atherogenic diet; however, the relative contributions of the neutral and acidic fractions to the increase in total excretion differed among species. The difference in percentage of dietary cholesterol absorbed may, in part, account for the large differences in serum cholesterol during the atherogenic diet period. Comparison with other published results indicates that of these species cholesterol metabolism in the baboon is most like that in the human.