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Biomedical subjects

M Carlsson

Publications and source records attributed to M Carlsson.

At least 163 records · Page 9Linked to original sources
PubMed1987

The intrinsic activities of the partial dopamine receptor agonists (-)-3-PPP and TDHL on pituitary dopamine receptors are lower in female than in male rats.

The abilities of the mixed agonists/antagonists on dopamine (DA) receptors, (-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine [-)-3-PPP) and transdihydrolisuride (TDHL), to suppress serum prolactin levels in acutely hyperprolactinemic male and female rats were investigated. gamma-Butyrolactone was used to deplete endogenous DA and raise serum prolactin concentrations. Both (-)-3-PPP and TDHL were found to cause sexually differentiated responses: (-)-3-PPP reduced serum prolactin levels dose dependently and effectively in males but caused only a modest decrease of prolactin release in females. Moreover, (-)-3-PPP antagonized the prolactin-suppressing effects induced by the DA receptor agonist (+)-3-PPP in females. Likewise TDHL decreased prolactin secretion markedly in males while it had only slight effects in females. It can be concluded from these results that the intrinsic activities of the partial DA agonists (-)-3-PPP and TDHL are lower in female than in male rats, suggesting a reduced responsiveness of hypophyseal DA receptors in females. Since DA levels in the pituitary portal circulation are higher in female than in male rats, this study gives further support to the hypothesis claiming an inverse relationship between the intrinsic activity of a mixed agonist/antagonist and the degree of previous stimulation of its receptor.

Animals↗
PubMed1987

High-performance liquid chromatography of 2-mercaptopropionylglycine and its metabolite 2-mercaptopropionic acid in plasma and urine after treatment with thiopronine.

2-Mercaptopropionic acid has been identified as a normal metabolite of 2-mercaptopropionylglycine (thiopronine) when this drug was given to humans and dogs. A high-performance liquid chromatographic method was developed to resolve the derivatives of these two thiols and thus enable simultaneous determination of the two compounds in plasma and urine.

Amino Acids, Sulfur↗
PubMed1987

Serotonergic influence on the growth hormone response to clonidine in rat.

Administration of the alpha 2-adrenoceptor agonist clonidine induces growth hormone (GH) release in rat and man. In the present study it is shown that the GH response to clonidine is weaker in rats exposed to depletion of both noradrenaline and serotonin (by means of reserpine or the combined treatment of FLA-63 and PCPA) than in animals exposed to noradrenaline depletion (by means of FLA-63) only. The possibility that an impaired serotonergic neurotransmission contributes to the blunted GH responses to clonidine observed in patients suffering from endogenous depression is discussed.

Animals↗
PubMed1987

Effects of recombinant interferon-alpha and -gamma on B-CLL cells in serum-free medium: expression of activation, differentiation, and CALLA antigens.

Chronic B-lymphocytic leukemia (B-CLL) cells from 10 patients were cultured serum-free with recombinant interferon (rIFN)-alpha 2, rIFN-gamma, or phorbol ester (TPA) for 5 days. All three agents induced functional differentiation, as evidenced by IgM secretion, without concomitant proliferation. A panel of monoclonal antibodies was used to detect changes in cell surface antigens defining pre-B cells (CALLA), resting B cells (HH1), early (4F2, MHM6) and late (anti-Tac, OKT9) B cell activation, and terminally differentiated B cells (OKT10). The activation markers 4F2, MHM6, and anti-Tac and the plasma cell marker T10 were all significantly induced with TPA, rIFN-alpha 2, an rIFN-gamma, whereas the expression of HH1 decreased. CALLA was detected on substantial proportions of differentiated (4-38%) but not resting (0-4%) B-CLL cells. The CALLA-positive B-CLL cells were negative for nuclear terminal deoxynucleotidyl transferase (TdT). The T9 antigen was expressed on TPA-treated cells (1-16%) only. The present findings indicate novel properties of IFN-alpha and IFN-gamma in inducing terminal differentiation of human monoclonal B cells without prior activation.

Antigens, Surface↗
PubMed1986

Growth hormone responses to clonidine and GRF in spontaneously hypertensive rats: neuroendocrine evidence for an enhanced responsiveness of brain alpha 2-adrenoceptors in genetical hypertension.

Clonidine induces growth hormone (GH) release in rat. According to previous investigations this effect is mediated by postsynaptic alpha 2-adrenoceptors in the hypothalamus exerting a stimulatory influence on the recently discovered GH releasing factor (GRF). In the present study it is demonstrated that spontaneously hypertensive rats (SHR) of the Wistar-Kyoto strain display enhanced GH responses to clonidine as compared to normotensive Wistar-Kyoto control rats. In contrast, the GH responses to GRF are similar in hypertensive and normotensive animals. These findings indicate that brain alpha 2-adrenoceptors are more responsive in SHR than in normotensive controls. Since the enhanced GH responses to clonidine were observed also in young, prehypertensive SHR they are probably not secondary to the elevated blood pressure. The possible importance of an altered alpha 2-adrenergic neurotransmission for the development of elevated blood pressure in SHR is discussed.

Animals↗
PubMed1986

The putatively selective dopamine autoreceptor antagonists (+)-AJ 76 and (+)-UH 232 stimulate prolactin release in rats.

The 2-aminotetralin derivatives cis-(+)-(1S,2R)-5-methoxyl-1-methyl-2-(n-propylamino)tetralin, (+)-AJ 76, and cis-(+)-(1S,2R)-5-methoxy-1-methyl-2-(di-n-propylamino)tetralin, (+)-UH 232, are novel centrally acting stimulants with a putative action as selective dopamine (DA) autoreceptor antagonists. In the present study these compounds were evaluated with respect to their effects on prolactin release in male rats. Both (+)enantiomers caused a pronounced increase in plasma prolactin levels in previously untreated animals. The effects of (+)-AJ 76 and (+)-UH 232 were virtually similar, except for a higher initial increase after the latter compound. In agreement with earlier reports, the reserpine-induced elevation of plasma levels of prolactin was strongly suppressed by the DA autoreceptor agonist B-HT 920. This effect of B-HT 920 was completely blocked by (+)-AJ 76 and by (+)-UH 232, indicating that both (+)enantiomers antagonize lactotroph DA receptors. The present findings support the notion that lactotroph DA receptors resemble DA autoreceptors rather than postsynaptic DA receptors. A possible difference between the auto-/lactotroph vs. postsynaptic DA receptors with respect to both the responsiveness to agonists and to the affinity of pure antagonists is discussed.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1986

Determination of 2-mercaptopropionylglycine in plasma and urine by high-performance liquid chromatography.

Methods for quantitative analysis of total and non-protein-bound 2-mercaptopropionylglycine (2-MPG) in plasma, and total 2-MPG in urine, have been developed. By reduction of urine, plasma or deproteinized plasma samples with tributylphosphine, 2-MPG is liberated from its disulphides, and after clean-up of the sample, 2-MPG is derivatized with N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide (DACM). The 2-MPG-DACM derivative is then quantified by high-performance liquid chromatography (HPLC) with fluorimetric detection. Both ion-suppression and ion-pair HPLC gave satisfactory chromatograms. The precision of the methods was satisfactory (coefficient of variation 3.1-5.8%), analytical recovery was quantitative (85-99%) and the two HPLC techniques were well correlated (r = 0.99). Five healthy subjects receiving 500 mg of 2-MPG showed maximal total plasma concentration of 13.8-26.9 mumol/l at 3-5 h after intake, and their non-protein-bound 2-MPG was, at the same time, 62-77% of the total 2-MPG. The urinary excretion was 27.8 +/- 3.8% (mean +/- S.D.) of the given dose, most of it excreted within 12 h after intake.

Amino Acids, Sulfur↗
PubMed1986

Does alprazolam, in contrast to diazepam, activate alpha 2-adrenoceptors involved in the regulation of rat growth hormone secretion?

The conventional benzodiazepine diazepam and the novel triazolobenzodiazepine alprazolam were compared with respect to effects on growth hormone (GH) release in reserpine pretreated rats. The reserpine pretreatment was undertaken to eliminate brain monoaminergic influence on GH secretion, hence obtaining a low GH baseline from which a drug induced increase could be easily detected. Previous studies have indicated that activation of brain alpha 2-adrenoceptors is an indispensable prerequisite for GH release induced by other agents such as serotonin and opiate receptor agonists. In line with these findings, diazepam was found to induce GH release in reserpine pretreated rats only when the alpha 2-receptor agonist clonidine was simultaneously administered. In contrast, alprazolam caused a dose-dependent increase in plasma GH when given alone to reserpine pretreated rats. This effect of alprazolam was effectively antagonized by either of the two selective alpha 2-receptor antagonists yohimbine or idazoxane. The data indicate that alprazolam, but not diazepam, activates brain alpha 2-adrenoceptors involved in rat GH regulation. The possibility that an alpha 2-agonistic profile of alprazolam may contribute to the suggested effectiveness of the drug in the treatment of panic disorder is discussed.

Adrenergic alpha-Antagonists↗
PubMed1986

Sexually differentiated actions of 3-PPP enantiomers on prolactin secretion.

The ability of the enantiomers of the atypical dopamine receptor agonist 3-(3-hydroxyphenyl)-N-n-propylpiperidine (3-PPP) to counteract gamma-butyrolactone-induced hyperprolactinemia was compared in male and female rats. Following gamma-butyrolactone (GBL) pretreatment serum prolactin concentrations were higher in female than in male rats. In males (-)-3-PPP tended to be somewhat less effective than (+)-3-PPP in decreasing serum prolactin concentrations (levels after (+)-3-PPP and (-)-3-PPP: 21% and 33%, respectively, of levels in GBL-pretreated control(s). In females the (-)-form induced a much weaker response than did the (+)-form (levels after (+)-3-PPP and (-)-3-PPP: 8% and 74%, respectively, of levels in GBL pretreated controls). Parallel experiments replacing GBL by reserpine yielded similar results. Data are discussed in terms of sex differences in responsiveness of pituitary dopamine receptors.

4-Butyrolactone↗
PubMed1986

A central serotonin receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin, has different effects on prolactin secretion in male and female rats.

Male and female rats were compared with respect to alterations in prolactin secretion induced by the serotonin receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). The dose-response curves after 8-OH-DPAT were irregular and had different shapes in the two sexes. In males, 0.1 and 0.3 mg/kg enhanced serum prolactin concentrations to about 200% of control values, whereas higher doses (1 and 3 mg/kg) had no effect on prolactin release. In females, in contrast, 0.1 mg/kg of 8-OH-DPAT tended to decrease serum levels of prolactin, while 0.3, 1, and 3 mg/kg elevated them in a dose dependent manner to maximally 700% of control values. The serotonergic agonist 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) (5 mg/kg), too, caused increased prolactin release in both sexes, and, again, females responded more forcefully. In males, but not in females, pretreatment with 8-OH-DPAT (1 mg/kg) reduced the 5-MeODMT-induced elevation of serum prolactin levels. The mechanism underlying the sexually differentiated effects of 8-OH-DPAT on prolactin secretion is discussed.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1986

The pelvic outlet. A comparison between clinical evaluation and radiologic pelvimetry.

A random sample of 798 primiparas was screened with clinical evaluation and radiologic low-dose pelvimetry of the pelvic outlet. The purpose was to study the accuracy of clinical evaluation in comparison with X-ray pelvimetry and to determine whether clinical evaluation could reveal any other factor influencing labor. A significant agreement between clinical and X-ray pelvimetry was found, but the sensitivity of clinical evaluation was low and as many as half the patients with a contracted pelvis, according to pelvimetry, were not detected. Delivery outcomes in two matched groups with similar pelvic outlet measurements but different clinical evaluation did not differ, indicating that clinical evaluation did not detect any other factor not revealed by X-ray pelvimetry.

Delivery, Obstetric↗