Dopamine in hypophysial stalk blood of the rhesus monkey and its role in regulating prolactin secretion

Numerous studies are suggestive of dopamine serving as the hypothalamic PRL-inhibiting factor in the monkey. In the present study, we measured dopamine concentrations in plasma collected from the hypophysial stalk and determined whether those concentrations were sufficient to account for the inhibiting effect on PRL secretion exerted by the hypothalamus. First, we collected hypophysial stalk blood from seven follicular phase monkeys (four anesthetized with pentobarbital and three with phencyclidine) using a transorbital surgical approach. Dopamine concentrations, measured with a liquid chromatographic-electrochemical procedure, averaged 0.76 ng/ml in stalk plasma and less than 0.1 ng/ml in peripheral plasma collected contemporaneously. Next, we determined the rate of dopamine infusion required to produce peripheral plasma concentrations of dopamine similar to those measured in hypophysial stalk plasma. In seven monkeys, a dopamine infusion rate of 0.1 microgram/kg BW . min produced plasma dopamine concentrations of 0.62 ng/ml, whereas a 10-fold higher rate (1.0 microgram/kg . min) produced plasma concentrations of 1.95 ng/ml. Then, we infused these doses of dopamine into intact follicular phase animals, stalk-transected animals, and estrogen-treated stalk-transected animals to determine their effect on PRL release. The physiological dose of dopamine (0.1 microgram/kg . min) significantly suppressed plasma PRL levels in intact follicular phase animals and estrogen-treated stalk-transected animals but not in untreated stalk-transected animals. The higher rate of dopamine infusion (1.0 microgram/kg . min) was required to inhibit PRL release in the latter group. These results demonstrate that dopamine is secreted by the hypothalamus into hypophysial portal blood in quantities sufficient to account for much of the PRL-inhibiting activity known to be caused by the hypothalamus. Moreover, the results suggest that estrogen reinforces the inhibitory effect of dopamine on PRL release in primates, in contrast to its antagonistic effect in rodents. (Endocrinology 108: 489, 1981)

Detection of ABO group-specific substances on the red cells of the cynomolgus monkey

Several attempts were made to demonstrate the presence of ABO blood group substances on the red blood cells (RBC) of the cynomolgus monkey. Neither the direct hemagglutination test nor the antibody absorption test was successful in detecting these substances from whole RBC, the stromata or the butanol extracts of RBC. By the heat elution of antibodies, however, the presence of ABH substances was demonstrated on RBC of every phenotype without fail. In all cases, there was a reciprocal relationship between the ABH substances of RBC and of saliva and the anti-A and anti-B antibodies in serum, being in good agreement with Landsteiner's rule. Accordingly, it can be concluded that a small amount of ABH substances must be present on RBC of the cynomolgus monkey.

Blood groups of Barbary apes (Macaca sylvanus)

32 Barbary macaques were all found to be secretors of the A and H blood group substances and to have an M-like agglutinogen on their red cells. Hemagglutination tests for other human-type red cell specificities were negative. In contrast, several so-called simian-type specificities were detected on the erythrocytes of Barbary apes by means of the cross-reacting rhesus and baboon antisera. Among these, only the specificities of the graded Drh blood group system were found to be polymorphic in this species of macaques. Blood groups of Barbary apes are compared with those of several other species of macaques and some taxonomic aspects of blood grouping tests are discussed.

Pregnancy effects on nonhuman primate high density lipoprotein

The concentration of cholesterol in high density lipoproteins (HDL) has been showed to be dramatically decreased during pregnancy in Macaca nemestrina. HDL were isolated from females of this species at various stages of pregnancy to determine if pregnancy also alters their composition and size. The chemical compositions of the HDL were determined nad found different in pregnant animals; the mass ratio of surface (coat) to center (core) constituents was higher, suggesting that the average size of HDL decreased during pregnancy. When measured chromatographically, the average size of HDL was found to decrease during pregnancy. This change in HDL size was accompanied by a minor alteration in apolipoprotein distribution.

Acute gastric dilation and rupture in Macaca arctoides associated with Clostridium perfringens

A clinical case of gastric dilation and rupture is described in an adult male Macaca arctoides. Clostridium perfringens was isolated from the heart blood and liver. Data collected from our macaque colony for 13 years indicated a mortality rate of 3.5% due to acute dilation.

Serum proteins of Macaca nigra. Identification and changes in nondiabetic and diabetic monkeys

Serum proteins of Macaca nigra were separated by agarose gel electrophoresis. Proteins identified were: albumin, alpha 1-globulin, alpha 2-macroglobulin, haptoglobin, beta 1C-globulin, and gamma 1- and gamma 2-globulins. Diabetic M. nigra had decreased gamma 2-globulin; borderline diabetics had increased beta 3-globulin.

Exposure of rhesus monkeys to 20 000 G steady magnetic field: effect on blood parameters

Sixteen monkeys were used in a study to determine the effects, or noneffects, of exposure to a steady magnetic field of 2 T (20 000 G). Arterial and venous blood samples were taken before, immediately after, and several weeks following the test. Blood gas analyses were made of arterial samples, and hemotologic cell data and Technicon SMAC analyses were made of venous samples. Differential and absolute white blood cell counts of segmented neutrophils and lymphocytes were considerably changed during the test, even for monkeys which were not exposed to the magnetic field. These changes have also been observed in monkeys whose environment and daily routine are modified appreciably. Eight of the 16 monkeys were tested twice: first, in the magnet with the magnet turned on, and second, two months later, in the magnet, but with the magnet turned off. A large superconducting magnet (0.63 m i. d. and 1.85 m long warm-air bore) was used, which accommodated two monkeys at one time. Paired-t tests of 45 blood parameters showed no significant differences between the two tests. Exposure to a gradient field compared with exposure to a uniform magnetic field showed no significant differences.

Effects of ketamine hydrochloride on the hemogram of rhesus monkeys (Macaca mulatta)

Ketamine hydrochloride administration altered the hemogram of rhesus monkeys when compared to physical restraint for venipuncture. The alterations were decreases in the leukocyte count, total plasma proteins, and hematocrit. The decrease in the leukocyte count was due primarily to a decrease in lymphocytes with a smaller decrease in neutrophils.

Comparative blood values of Macaca mulatta and Macaca fascicularis

Hematological and clinical biochemistry values of two species of monkeys (Macaca mulatta and Macaca fascicularis) were measured by using auto-analyzers. WBC and RBC counts of M. fascicularis were high and Hb, MCV, MCH and MCHC values of M. fascicularis were low in comparison with those of M. mulatta. Albumin and creatinine levels of M. fascicularis were lower than those of M. mulatta. Total protein and A1P values of female M. fascicularis were higher than those of female M. mulatta. Differences between the sexes were observed in MCV, inorganic phosphorus, total protein, albumin and creatinine in M. mulatta, whereas in M. fascicularis, such differences were demonostrated as to creatinine, phospholipids and triglycerides.

Silent delta-globin gene in Old World monkeys

The delta polypeptide chain is present in the adult hemoglobin of all higher primates except Old World monkeys. Because Old World monkeys have evolved from higher primate ancestors, it can be concluded that the ability to synthesize this polypeptide has been lost relatively recently. It is shown here that the gene for delta globin exists in two of these species, the rhesus monkey (Macaca mulatta) and the baboon (Papio papio). Restriction endonuclease fragments of monkey genomic DNA bearing the delta- and beta-globin genes were detected after hybridization of human globin cDNA probes to filter-bound primate DNAs according to the Southern method. A restriction map prepared for rhesus DNA was identical in overall organization to the map of the human region. This indicates that large deletions or additions of DNA are not responsible for the Old World monkeys' lack of delta globin.

Copulation, dominance, and plasma androgen levels in adult Rhesus males born and reared in the laboratory

The subjects consisted of adult male rhesus macaques (N = 22) that had been born and reared in the laboratory and had failed to ejaculate in standardized tests of sexual behavior in adulthood. As infants they had been given regular but limited social experience, and as juveniles and adults they had been housed in individual cages. Saphenous vein blood (3 ml) was taken on each of 5 days; the plasma was removed and stored for later assay for testosterone (T) and dihydrotestosterone (DHT). The males were then released into a 1-acre outdoor enclosure with 8--14 adult females. Behavior was observed daily for 2 hr, and blood was taken from the males once a week for hormone assays. During the first 8 weeks, four males ejaculated, and they were removed from the enclosure. During the second 8 weeks, four additional males ejaculated, and they were also removed from the enclosure. The remaining 14 males were never observed to achieve intromission or to ejaculate during the 28 weeks in the enclosure, but 11 masturbated to ejaculation. There was no evidence that individuals with high plasma T levels were more sexually active or more dominant than males with lower T levels. Mean levels of plasma T were within the range observed in wild-born rhesus males, but the level of sexual performance was not. At the end of the 12th week, all of the females initially in the enclosure were removed and 13 different adult females were introduced. Three females became pregnant.

Concentrations of melatonin in the plasma of the rhesus monkey (Macaca mulatta)

A radioimmunoassay for the determination of concentrations of melatonin in the plasma of rhesus monkeys has been developed. Antiserum for the assay was raised against N-acetyl serotonin and there was a 100% cross-reaction with melatonin. Cross-reactivity with closely related indoles, precursors and metabolites was less than or equal to 1%. The lower of sensitivity of the assay was 4 pg/tube. The assay has been used for the investigation of diurnal variations and cyclical changes in melatonin concentrations in peripheral plasma of the rhesus monkey. The concentrations of melatonin ranged between 26.6 and 85.3 pg/ml during sampling for 24 hr. There was a distinct diurnal variation in the concentration of melatonin in plasma. The concentration during darkness (61.0+/-7.1 (S.E.M.) pg/ml) was greater (P less than 0.01) than that during illumination (40.1+/-6.1 pg/ml). There were no significant differences in the concentration of melatonin in plasma at any time during the 28 day menstrual cycle of the rhesus monkey.

Differentiation of sex steroid-binding protein in adult rhesus monkeys

Several species of primates have sex differences in sex steroid-binding protein (SBP), female adults having higher serum binding capacities (micrograms of dihydrotestosterone bound per deciliter) than male adults, e.g., male humans, 1.28 +/- 0.4; human females, 2.86 +4- 0.9; Macaca nemestrina male animals, 5.62 +/- 1.24; Macaca nemestrina female animals, 11.07 +/- 1.85 (means +/- standard deviations). SBP correlates inversely with metabolic clearance rates of testosterone (T). The sex difference was identified in rhesus monkeys, six per group, evaluated 4 years after postpubertal castration: male animals 3.95 +/- 1.14; female animals 5.85 +/- 0.98 (p less than 0.05). Estradiol-17 beta (E2) pellets producing physiologic levels of E2 in female monkeys obliterated the sex difference by increasing SBP in male animals. After withdrawal of E2, physiologic levels of T in male monkeys produced a marked decrease in SBP levels (p less than 0.01), and the sex difference reappeared; castrated female animals and prenatally androgenized female animals responded similarly to T (2.81 +/- 0.81 and 2.64 +/- 0.49, respectively). Both values were greater (p less than 0.05) than that of the male group (2.02 +/- 0.33). These data suggest that the sex steroid milieu influences the binding capacity of SBP for potent androgens in adulthood but that the differentiation of the SBP sex in rhesus monkeys is determined by factors other than prenatal androgen exposure.

The A-B-O blood groups of rhesus monkeys: new observations

A rhesus monkey family is described in which a group A offspring was born from a group AB mother and a group B male parent. Discovery of A and O genes in rhesus monkeys indicates that this species of macaques is polymorphic for the A-B-O blood groups, and not monomorphically B, as previously believed.

Platelet monoamine oxidase activity correlates with social affiliative and agonistic behaviors in normal rhesus monkeys

After a 4-mo study period, quantitative measures of stable behavioral traits in individual rhesus monkeys correlated significantly with platelet monoamine oxidase (MAO) activity. In particular, behavioral items reflecting social activity and social contact, both agonistic and affiliative, were inversely correlated with enzyme activity. Time spent alone was positively correlated. Since platelet MAO activity is generally stable and predominantly controlled by genetic factors, it might serve as a "genetic marker" for individual differences in "normal" behaviors possibly related to differences in MAO activity in the brain and other tissues.

[Radioimmunologic method of determining 11 steroids in small samples of monkey blood plasma]

A radioimmunological method is described for simultaneous estimation of hestagenes, estrogenes, androgenes and their precursors in small samples of blood plasma obtained from peripheric blood of hamadryads (Papio hamadryas) and macaques (Macaca rhesus). Use of highly specific antisera and of chromatographic isolation of each steroid on columns with celite enabled to estimate the concentration of 11 steroids in 1.1 ml of blood plasma with high accuracy. Standard curve and analysis of its linearity were carried out in the coordinate system logit-log.

Fractionation of Plasmodium knowlesi-induced antigens of rhesus monkey erythrocyte membranes

In order to characterize parasite-induced host cell membrane antigens, the plasma membranes of Plasmodium knowlesi-infected rhesus erythrocytes have been compared with those of normal red cells and purified schizonts by immunochemical and biochemical techniques. Host cell membranes and schizonts were separated by differential centrifugation following nitrogen decompression. Isolated schizonts were further fractionated into several subcellular compartments. Crossed-immune electrophoresis, against monkey anti-schizont serum, of Triton X-100-solubilized material identified 7 P. knowlesi-specific antigens, of which 4 could be detected only in the host cell membranes. These membranes also contained 3 proteins, with relative molecular masses of 55 000, 65 000 and 90 000 and isoelectric points at pH 4.5, 4.5 and 5.2, respectively, which are lacking in normal membranes. Pulse-chase experiments with ((14)C)-glucosamine showed that these parasite-induced host cell membrane components are glycoproteins.