Protein Synthesis in the Rat Anterior Pituitary. III. The Fate of Total Protein, Prolactin and Growth Hormone Labeled in an in Vitro Incubation*

Samli, Marcqueta H.; Lai, Minchao

doi:10.1210/endo-93-4-767

Cited by 9 publications

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“…Intra-assay coefficient of variation (CV) was 4.6%; interassay CV was 13.4%. Linearity and parallelism for wolf PRL was established by serial dilutions of wolf serum samples and wolf pituitary extracts obtained by a modification of the method described by Samli and Lai (1973).…”

Section: Assaymentioning

confidence: 99%

Characterization of prolactin secretion in gray wolves (Canis lupus)

Kreeger¹,

Seal²,

Cohen³

et al. 1991

Can. J. Zool.

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1991. Characterization of prolactin secretion in gray wolves (Canis lupus). Can. J. Zool. 69: 1366 -1374 . From 1980to 1989 were conducted on 28 intact (13 females, 15 males) and 10 neutered wolves (5 females, 5 males) to characterize prolactin (PRL) release. From these studies, we have (i) adapted and validated the canine PRL radioimmunoassay of Parlow for wolves; (ii) determined that the plasma half-life of PRL is 44 min; (iii) demonstrated that anesthesia with 400 mg ketamine plus 50 mg promazine, 400 mg ketamine plus 30 mg xylazine, or 7.5 pg kg-' etorphine plus 0.5 mg . kg-' xylazine, administered intramuscularly, does not alter PRL rhythms or control mechanisms; (iv) indicated that PRL is not secreted in response to handling stress (P 2 0.78) or by activation of the hypothalamic-pituitary-adrenocortical axis simulated by intravenous injection of 50 pg ovine corticotropin-releasing factor (P = 0.28); (v) demonstrated a circannual rhythm in intact and neutered wolves characterized by elevated PRL levels just prior to summer solstice; (vi) detected a circadian PRL rhythm in females; (vii) provided evidence for dopaminergic control of PRL secretion by injecting 2.0 mg kg-' promazine, a dopaminergic antagonist, which increased PRL levels significantly (P = 0.000 1); (viii) shown that intravenous injection of 100 pg thyrotropin-releasing hormone results in PRL release (P = 0.0001), but that this release could not be attenuated by prior administration of 1 . O mg . kg-' of the opioid antagonist naloxone; (ix) determined that feeding 2.0 mg of melatonin daily reduced basal PRL levels in May and June (P = 0.03), but not in OctoberDecember (P = 0.42), and that PRL stimulation with 100 pg thyrotropin-releasing hormone was consistently lower in melatonin-fed wolves; and (x) shown that pinealectomy does not abolish the circadian PRL rhythm nor alter absolute PRL levels relative to sham-operated control wolves (P = 0.33). KREEGER, T. J., SEAL, U. S., COHEN, Y., PLOTKA, E. D., et ASA, C. S. 1991. Characterization of prolactin secretion in gray wolves (Canis lupus). Can. J. Zool. 69 : 1366-1374.De 1980 B 1989, des experiences sur 28 (13 femelles, 15 miles) loups intacts et 10 (5 femelles, 5 mHles) loups chhrCs ont permis d'Ctudier la liberation de la prolactine (PRL). Au cours de l'itude, (i) nous avons adapt6 B des loups et rendu valide la procCdure radio-immunologique de Parlow utilisCe dans 1'Ctude de la prolactine de chien; (ii) nous avons CvaluC B 44 min la demi-vie plasmatique de la prolactine; (iii) nous avons dCmontrC que 1'anesthCsie provoquCe par une injection intramusculaire de 400 mg de kCtamine plus 50 mg de promazine, 400 mg de kCtamine plus 30 mg de xylazine ou 7,5 pg . kg-' d'Ctorphine plus 0,5 mg .kg-' de xylazine n'affecte pas la vitesse de IibCration de la prolactine ou les mkcanismes de contr8le; (iv) nous avons dCmontrC que la prolactine n'est pas sCcrCtCe en rCaction au stress dCclenchC par la manipulation ( P 1 0,78) ou par activation de l'axe hypothalamus-hypophyse-adrCnocortex simulCe par une inje...

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Section: Assaymentioning

confidence: 99%

Characterization of prolactin secretion in gray wolves (Canis lupus)

Kreeger¹,

Seal²,

Cohen³

et al. 1991

Can. J. Zool.

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“…Moreover, the values may be a reflec¬ tion of maternal or fetal rather than placental function (Klopper, 1969). There¬ fore we have used the in-vitro pulse-chase system developed by Meldolesi et al Samli &Lai (1973) to study the secretion of prolactin and growth hormone from rat pituitaries. The tissue is given a radioactive label for a short period of time, and the transport of a constant amount of radioactive molecule can be subsequently followed (Schramm, 1967).…”

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confidence: 99%

Secretion of Human Chorionic Gonadotrophin by the Early Placenta in Vitro

Patrito¹,

Flury²,

J³

et al. 1975

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The secretion in vitro of HCG and proteins was studied in fragments of placenta from women in the first trimester of pregnancy by a pulse-chase system. A 10-min pulse with [3H]leucine was used. It was concluded that the approximate half-time of release for HCG was 150 min. Proteins precipitable with trichloroacetic acid had a bi-exponential pattern, the half-times of release being 100 and 270 min. These rates of release indicate that the HCG produced by the early placenta was rapidly passed into the circulation rather than stored.Previous studies have established that HCG and proteins synthesized in vitro by placental tissue taken from women in the first trimester of pregnancy are secreted into the incubation media (Benagiano et al., 1972;Patrito et al., 1973).The rate of release of these macromolecules is not known and difficult to study in women in vivo, because the amount of radioactive material to be administered may be hazardous (Lerner et al., 1971). Moreover, the values may be a reflec¬ tion of maternal or fetal rather than placental function (Klopper, 1969). There¬ fore we have used the in-vitro pulse-chase system developed by Meldolesi et al. Samli &Lai (1973) to study the secretion of prolactin and growth hormone from rat pituitaries. The tissue is given a radioactive label for a short period of time, and the transport of a constant amount of radioactive molecule can be subsequently followed (Schramm, 1967). Placentae were obtained from five women in the first trimester of pregnancy after therapeutic abortion induced by curettage. Tissues were collected in cold Ringer solution and used within 1 hr. Fragments of each placenta, weighing approximately 5 to 10 mg, were washed several times with cold Krebs-Ringer bicarbonate, pH 7-2 (Krebs, 1950). Aliquots of 100 mg were placed in 15-ml Ehrlenmeyer flasks containing 1 ml Krebs-Ringer bicarbonate and 8 µ Ci L-[4,5-3H]leucine (sp. act. 41-2 Ci/mmol) (New England Nuclear Corporation).The flasks were left in a cold water-bath for 15 min and then pulse-labelled for 10 min at 37°C in an atmosphere of 95% C02/5% 02 in a shaking bath at 1*5 cycles/sec. The fragments of placenta were then separated from the radio¬ active incubation media, washed three times with large volumes of warm in-509

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Heterogeneity of the MtTW₁₅ mammosomatotropic tumor. I. Light microscopic evaluation of cell types by means of immunocytochemistry, morphometric quantitation, fluorescence cytophotometry and radioimmunoassay

et al. 1978

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Large MtTW15 pituitary tumors produced 200- to 800-fold elevations in serum growth hormone (GH) and prolactin (PRL) levels. Female tumor hosts showed doubling in body weight, milk secretion, and a 2-fold hepatosplenomegaly. Pituitaries of host animals were reduced by about 50% in both weight and concentrations of GH and PRL. Large tumors were well-encapsulated, multinodular and showed variable amounts of necrosis and hemorrhage. Cytofluorometric analysis revealed a range of 100-fold in nuclear DNA content of tumor parenchymal cells which were chromophobic, pleomorphic and frequently mitotic. Concentrations of hormones in tumors were less than in normal pituitaries and highly variable with the ratio of GH/PRL ranging up to 30-fold within the same tumor. Immunostaining and linear scanning quantitation showed that about 50% of the tumor cells contained immunodetectable hormones. Comparison of immunostained adjacent sections showed that hormone-containing tumor cells were pleomorphic, unequally distributed within nodules, lacking in distinctive identifying morphological characteristics and that they contained GH or PRL but not both hormones simultaneously. Collectively our results show that large MtTW15 tumors are comprised of a markedly heterogeneous population of tumor cells and they suggest that the hormone-containing cells are monohormonal secreting tumor cells which can produce GH or PRL but not both hormones.

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Protein Synthesis in the Rat Anterior Pituitary. III. The Fate of Total Protein, Prolactin and Growth Hormone Labeled in an in Vitro Incubation*

Cited by 9 publications

References 0 publications

Characterization of prolactin secretion in gray wolves (Canis lupus)

Characterization of prolactin secretion in gray wolves (Canis lupus)

Secretion of Human Chorionic Gonadotrophin by the Early Placenta in Vitro

Heterogeneity of the MtTW₁₅ mammosomatotropic tumor. I. Light microscopic evaluation of cell types by means of immunocytochemistry, morphometric quantitation, fluorescence cytophotometry and radioimmunoassay

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Protein Synthesis in the Rat Anterior Pituitary. III. The Fate of Total Protein, Prolactin and Growth Hormone Labeled in an in Vitro Incubation*

Cited by 9 publications

References 0 publications

Characterization of prolactin secretion in gray wolves (Canis lupus)

Characterization of prolactin secretion in gray wolves (Canis lupus)

Secretion of Human Chorionic Gonadotrophin by the Early Placenta in Vitro

Heterogeneity of the MtTW15 mammosomatotropic tumor. I. Light microscopic evaluation of cell types by means of immunocytochemistry, morphometric quantitation, fluorescence cytophotometry and radioimmunoassay

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Heterogeneity of the MtTW₁₅ mammosomatotropic tumor. I. Light microscopic evaluation of cell types by means of immunocytochemistry, morphometric quantitation, fluorescence cytophotometry and radioimmunoassay