Evidence for dopaminergic and serotonergic regulation of prolactin cell activity in the trout Salmo gairdneri

The control of prolactin (PRL) cell activity in Salmo gairdneri was investigated in vivo and in vitro. In some in vivo experiments treatment was followed by estimation of pituitary PRL content by gel electrophoresis or of PRL cell nuclear area by light microscopy. In the remainder, treatment was followed by incubation of the pituitary glands in drug-free medium for estimation of PRL synthesis and release. The dopamine precursor, l-dopa (20 mg/kg), reduced pituitary PRL content. Conversely, the dopamine-receptor blocker, domperidone (10 mg/kg), increased total PRL content and amount released in the subsequent incubation. The initial serotonin precursor, l-tryptophan (75 mg/kg), increased pituitary PRL content and PRL cell nuclear area. 5-HTP (20 mg/kg), the immediate serotonin precursor, increased both percentage PRL release and total PRL levels during subsequent incubation. Pargyline (25 mg/kg) treatment to inhibit serotonin catabolism elevated PRL levels in pituitary and medium during subsequent incubation. The serotonin synthesis blocker, parachlorophenylalanine (pCPA; 100 mg/kg), nonsignificantly reduced PRL cell nuclear area. When this was followed by incubation, percentage PRL release and total PRL fell significantly. During in vitro incubation, dopamine (2 μg/ml) reduced the release of PRL into the medium, while serotonin (10^?5M) increased PRL release. These results suggest that both an inhibitory dopaminergic and a stimulatory serotonergic system may be involved in PRL cell regulation in S. gairdneri. The lack of any significant effect of cortisol (1 μg/ml), somatostatin (300 ng/ml, GABA (100 ng/ml) and TRH 100 ng/ml) on PRL release in vitro suggested little or no involvement of these putative regulatory factors in PRL cell regulation.     

In vitro conversion of androgen to estrogen in amphioxus gonadal tissues

The ability to convert androgen to estrogen (aromatization) is a constant feature of gonadal and neural tissues in all major vertebrate groups. In experiments reported here, the existence of this pathway was investigated in the protochordate amphioxus (Branchiostoma lanceolatum). Following incubation with [³H]19-hydroxyandrostenedione, gonadal homogenates contained authentic estrone and estradiol-17β, as determined by derivative formation and recrystallization to constant specific activity. Cephalic (“brain”) and other segments were aromatase negative. The results indicate that a potential for estrogen biosynthesis in the gonads predates that in other tissues and arises prior to the evolution of true vertebrates.     

Ovulation hormone,nutritive state,and female reproductive activity in Lymnaea stagnalis

A study of the relation between nutritive state and female reproductive activity as affected by the ovulation hormone (CDCH) has been made in the freshwater pulmonate snail Lymnaea stagnalis. CDCH is produced by the neuroendocrine caudodorsal cells (CDC) in the cerebral ganglia. Spontaneous oviposition ceased within 6 days of the beginning of a starvation period. This is most probably partially due to a reduction in the CDC activities because (1) quantitative electron microscopy showed a nearly 80% decrease in the number of release phenomena in the CDC-axon terminals in the neurohemal area in the intercerebral commissure, and (2) a bioassay showed a considerable reduction in the amount of CDCH in this area. During starvation the ovotestis and the female accessory sex organs became progressively less sensitive and, after 25 days, were completely insensitive to injected CDCH. This was indicated by a decrease in the responses to CDCH injection and, correspondingly, by a gradual increase in the CDCH thresholds for ovulation and egg formation. It is argued that the insensitivity may be caused by a reduction in the activities of the endocrine dorsal bodies. During refeeding, CDCH injections again become effective in inducing egg mass production, followed by resumption of spontaneous oviposition. This suggests a rapid restoration of DB and CDC activities following refeeding.     

Primary structures of multiple forms of urotensin II in the urophysis of the carp, Cyprinus carpio

Multiple forms of urotensin II (UII), one of the hormonal peptides of the caudal neurosecretory system of fishes, were purified from the urophyses of the carp, Cyprinus carpio. Three distinct peaks with UII activity (classified as UII-α, -β and -γ) were separated by reverse-phase high-pressure liquid chromatography (HPLC). Edman degradations as well as digestion with carboxypeptidase A revealed the primary structures of these peptides as

The results of thin-layer chromatography, HPLC, amino acid analysis, and sequencing indicate that UII-α and -γ are homogeneous. UII-β appears, however, to be a mixture of two components, differing only at position 2. Thus, in the carp urophysis, four forms of UII appear to be present, although the separation of two components in UII-β has not been obtained. Sequence of positions 6–11 is common to all forms of UII isolated from the carp, sucker (Catostomus commersoni) and goby (Gillichthys mirabilis).     

Specific binding of 1,25 dihydroxyvitamin D3 in lymphocytes

We examined ten cellular or tissue sources of lymphocytes for specific binding of 1,25(OH)₂D₃, the hormonally active form of vitamin D₃. A specific-binding protein was found in three of these sources. Scatchard analysis of cytosol from a follicular lymphoma cell line revealed binding sites with a Kd of 7.0 × 10^?11 and a receptor concentration of 6.6 fmol/mg protein. Sucrose density centrifugation of ³H-1,25(OH)₂D₃ labeled cytosol showed a 3.75 peak which was absent in cytosols incubated with excess nonradioactive 1,25(OH)₂D₃. The relative amounts of vitamin D₃ metabolites required to displace 50% of the specifically bound ³H-1,25(OH)₂D₃ were 1,25(OH)₂D₃: 1,24,25(OH)₃D₃: 25(OH)D₃: 24,25(OH)₂D₃ = 1: 180: 1000: 2700. Excess vitamin D₃, cortisol, and estradiol failed to displace ³H-1,25(OH)₂D₃. Scatchard analysis of spleen cytosol from a patient with prolymphocytic transformation of chronic lymphocytic leukemia demonstrated a binding protein with a Kd of 1.2 × 10^?10 and a receptor concentration of 0.2 fmol/mg protein. DNA cellulose binding confirmed the presence of the specific-binding protein in this cytosol. Specific binding of ³H-1,25(OH)₂D₃ was also quantitated in a cell line from a patient with Burkitt's lymphoma with a Kd of 0.3 × 10^?10 and a receptor concentration of 29.6 fmol/mg protein. No specific binding of ³H-1,25(OH)₂D₃ was observed in lymphocytes from seven other malignant and nonmalignant sources. These results are the first to demonstrate a specific-binding protein for 1,25(OH₂D₃ in lymphocytes from tissue and from these specific cell lines. The presence of this protein in some lymphocytes but not others may reflect the state of activation of the lymphocytes.     

Cigarette smoking,physical activity,and alcohol consumption: Relationship to blood lipids and lipoproteins in premenopausal females

A total of 164 premenopausal female subjects were randomly selected for evaluation from a much larger pool of volunteers. The relationships between blood lipid and lipoprotein levels as dependent variables and cigarette smoking, physical activity, and alcohol consumption were determined from partial regression coefficients. A lower HDL-C level (10.1 mg/dL) was seen in smokers v nonsmokers. For each ounce of alcohol consumed, HDL-C level was higher by 2.8 mg/dL, and greater physical activity was associated with a higher HDL-C level of 8.6 mg/dL. An analysis of covariance with covariance adjustments for age and body fat revealed that smokers who regularly exercise or consume alcohol had significantly lower HDL-C levels than nonsmokers with similar habits. Subjects who both exercise and consume alcohol demonstrated higher HDL-C levels than those who indulge in one or the other separately. Results suggest that cigarette smoking may attenuate the effects of chronic exercise or alcohol consumption, or of both, to raise HDL-C levels. Also, chronic exercise and alcohol consumption may exert an additive effect, raising HDL-C level.     

Direct effect of human growth hormone to inhibit glucose uptake in cultured human fibroblasts

We have examined the effect of human growth hormone (HGH) on both basal and insulin stimulated glucose uptake in human fibroblasts. High concentrations of HGH (100 μg/mL) depressed both basal and insulin-stimulated glucose uptake by 25%. Significant inhibition was not seen at concentrations below 50 μg/mL of HGH. HGH-related hormones like human prolactin and ovine growth hormone had no effect on glucose uptake while high concentrations of ovine prolactin reduced basal glucose uptake, albeit to a lesser degree than HGH. In conclusion, high concentrations of HGH act independently of insulin to inhibit glucose uptake in human fibroblasts. These data may help explain the glucose imbalance and insulin resistance that is characteristic of acromegaly.     

Sex and insulin sensitivity

To analyze whether enhanced adiposity in females as compared with males is associated with a decreased sensitivity to insulin, a group of healthy normal weight females (n = 13, age 21 ± 1 years) and males (n = 11, age 23 ± 1 year, mean ± SEM) was studied. In each subject, body composition (% fat and % muscle), maximal aerobic power (V_O2 max) and whole body insulin-mediated glucose metabolism were measured. The group of women had a higher percentage of fat to total body weight (P < 0.001) and a lower percentage of muscle (P < 0.001) than the group of men. The higher percentage of fat in women compared with males was due to enhanced peripheral fat accumulation in the arm and thigh regions. V_O2 max levels were comparable in both groups (48 ± 1 mL/kg/min for women, 53 ± 2 mL/kg/min for men, P = NS). The rate of glucose metabolism (M) was comparable in women (8.78 ± 0.74 mg/kg/min), and men (8.31 ± 0.89 mg/kg/min) when expressed per kilogram of total body weight, but when expressed per kilogram of muscle tissue (M_m), it was 45% higher in women (29.4 ± 2.4 mg/kg/min) than in men (20.2 ± 1.6 mg/kg/min, P < 0.005). Partial correlation analysis indicated that the percentage of fat was inversely related to M and M_m in both women (P < 0.05) and men (P < 0.05), but not to percentage of muscle or V_O2 max. Conclusions: (1) Insulin-mediated glucose disposal is inversely related to adiposity in normal weight healthy males and females. (2) Women and men utilize equal amounts of glucose despite a higher adiposity in females. (3) Since muscle tissue utilizes most of intravenously administered glucose, this result indicates enhanced glucose uptake by muscle tissue in females compared with males. (4) Elevated glucose uptake by muscle in women may provide a mechanism by which women are protected against excessive hyperglycemia despite their smaller amount of glucose-consuming tissue.     

Platelet aggregation in Poiseuille flow: II. Effect of shear rate

Using a double infusion technique described in the previous paper, the effect of shear rate, G, on platelet aggregation was studied in citrated platelet-rich plasma in Poiseuille flow over a range of mean linear flow rates, $\text{u}{}_3$ from 50 to 1500 μm sec^?1 corresponding to $\text{G}$ from 2 to 54 sec^?1. At 1 μm ADP, aggregates were formed at all $\text{u}{}_3$ and, except at the lowest flow rate, both the degree of aggregation (net fraction of cells in aggregates, A′) and size of the aggregates increased with distance down the tube. The degree of aggregation was both time and shear rate-dependent. Over the first 10 sec, A′ appeared to be independent of the mean transit time indicating that the collision capture efficiency decreased with increasing G. Thereafter, A′ increased with increasing shear rate leading to the formation of an appreciable number of aggregates >10 cells at $\text{G}\text{> 24}\text{sec}{}^{\mathrm{?1}}$. Small aggregates initially formed near the tube wall and, as they grew in size, migrated toward the axis as their rotation was physically impeded by the wall. In addition, the values of A′ in cPRP from five female donors were significantly greater than those from five male donors.     

Contribution of Frank ECG measurements to the quantitative estimation of old anterior myocardial infarction

Twenty scalar and vector measurements of the Frank ECG were compared between men categorized as having suffered nontransmural (n = 47) and transmural anterior myocardial infarction (n = 124), on the basis of clinical and angiocardiographic findings. Variables which showed significant differences of group means between cases with anterior wall hypokinesis and anterior wall akinesis and/or dyskinesis were submitted to linear discriminant-function analysis. The stepwise selection procedure of Rao's method demonstrated the three most decisive variables for differentiation to be: (1) the angular sum of dorsal displacement of the 5 initial QRS vectors obtained at 0.01 sec intervals (sum of negative azimuth angles); (2) the Q duration in lead Z (anterior force); and (3) the Q duration in lead X (rightward force). The classification routine can identify correctly 81% of the nontransmural and 79% of the transmural anterior infarctions. The high percentages of correctly classified nontransmural and transmural infarctions show significant diagnostic potential for patient management. From the results of discriminant-function analysis, it is apparent that the sum of negative azimuth angles derived from the dorsally directed vectors during the first half of QRS exceeds substantially the scalar variables in their contribution to differentiation of the two conditions.