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Biomedical subjects

R Di Carlo

Publications and source records attributed to R Di Carlo.

At least 37 records · Page 2Linked to original sources
PubMed1993

Further evidence for the involvement of prolactin in the inflammatory response.

The pro-inflammatory activity of prolactin (PRL) was clearly demonstrated in our previous research on rat paw oedema. In the present study we report our results on the activity of PRL on other animal models of acute and chronic inflammation. Repeated administration of ovine PRL provoked a significant increase in the inflammatory parameters in experimental carrageenan pleurisy (leukocytes number and prostaglandin E2 concentration in the exudate). A pro-inflammatory effect was also present after a hyperprolactinaemia induced by pituitary gland graft. Moreover, the inflammatory response to polyester sponge implantation was significantly potentiated by oPRL, whereas the hormone was completely inactive on cotton pellet granuloma test. A possible involvement of prostaglandins in the pro-inflammatory activity of PRL is suggested.

Analysis of Variance↗
PubMed1993

Synthesis and muscarinic receptor binding profiles of antagonist benzotriazole derivatives.

A series of benzotriazole derivatives were synthesized and tested in order to determine their activities for muscarinic receptor subtypes (M1, M2 and M3). Binding affinities were measured as KI values by competition against [3H]-N-methylscopolamine in rat cortex, atria and ileum. Pharmacological in vitro tests were performed on isolated tissue preparations (rabbit vas deferens, guinea pig atria and ileum); the compounds showed antimuscarinic activity. The synthesized ligands were characterized by moderate activity; however, some of them displayed interesting selectivity profiles (M2/M1 and M2/M3); particularly, the selectivity exhibited by the benzotriazole derivative 14b was quite similar to that observed for AF-DX 116, a typical M2 specific antagonist.

Animals↗
PubMed1992

Effect of S-adenosyl-L-methionine on brain muscarinic receptors of aged rats.

The number of muscarinic receptors in the striatum and hippocampus of aged rats is significantly lower than the number measured in young animals. The treatment of aged rats for 30 days with S-adenosyl-L-methionine (SAM) restored the number of muscarinic receptors to levels found in the striatum and hippocampus from young animals. We did not observe a clear-cut difference between the dissociation constants of untreated young and untreated or SAM-treated aged rats, whereas the binding capacity varied. Moreover, in vitro addition of SAM to hippocampal membranes from aged rats resulted in a significant increase in the number of binding sites. This in vitro effect was antagonized by S-adenosyl-L-homocysteine, a specific in vitro inhibitor of methyltransferase activity. The reduction in the muscarinic receptor density could be related to a decrease in neuronal membrane fluidity induced by aging, while its increase after SAM treatment might be ascribed to the ability of this methyl donor to increase the fluidity of cell membranes by stimulating phospholipid synthesis.

Aging↗
PubMed1992

Characterization of prolactin receptor in human brain and choroid plexus.

We have studied the binding of 125I-labeled human prolactin (PRL) to membranes from various regions of the human brain (hypothalamus, cerebral cortex, cerebellum and choroid plexus) derived from autopsy specimens. Among the various regions studied, the choroid plexus of both male and female subjects showed the highest specific binding and a clearly detectable specific binding was also observed in the hypothalamus of both sexes, whereas it was very low in other brain regions. No significant sex differences in PRL binding to various brain regions were observed except for the hypothalamus where a higher binding was seen in female subjects. The binding did not vary with the age of the subjects. Moreover, the cause of death and the time elapsed from death to autopsy in this study did not affect the binding significantly. The binding of 125I-labeled human PRL to hypothalamus and choroid plexus membranes from female specimens was inhibited in a dose-dependent manner by both unlabeled human and ovine PRL and by human growth hormone (GH), but not by other polypeptide hormones. Scatchard analysis of the binding revealed the presence of saturable binding sites with low capacity and high affinity for human PRL ligand. These results provide strong preliminary evidence for the presence of PRL binding sites in the human brain.

Animals↗
PubMed1992

Effects of prolactin on rat paw oedema induced by different irritants.

Evidence suggests that prolactin (PRL) may have a role in immune function, but no data exist on the possible interference between PRL and inflammatory processes, in spite of the known correlation between inflammatory and immune reactions. In the present study the activity of prolactin on rat paw oedema was investigated. Repeated administrations of ovine PRL or a hyperprolactinaemia induced by pituitary gland graft provoked an evident increase of the inflammatory response induced by carrageenan. This effect was also present when adrenalectomised animals were used. Indomethacin completely suppressed the pro-inflammatory effect of ovine PRL; bromocriptine reduced the paw oedema, but when both bromocriptine and PRL were administered the two opposite effects seem to annual each other. Also phospholipase A2-induced paw oedema was potentiated by PRL pretreatment and inhibited by bromocriptine, whereas in dextran or serotonin-induced paw oedema both PRL and bromocriptine were ineffective. A possible involvement of prostaglandins and/or of phospholipase A2 in the pro-oedemigenic activity of PRL is suggested.

Adrenalectomy↗
PubMed1991

Distribution and characterization of prolactin binding sites in the male and female rat brain: effects of hypophysectomy and ovariectomy.

The binding of 125I-labeled rat prolactin (125I-rat PRL) to membranes from different regions of the rat brain was studied. Among these regions the hypothalamus showed the highest specific binding. Clearly detectable specific binding was also observed in substantia nigra, whereas it was very scanty in other brain regions. No significant sex differences in PRL binding to various brain regions were observed, except for hypothalamus where a higher binding was observed in female rats. The binding of 125I-rat PRL to hypothalamus from female rats was inhibited in a dose-dependent manner by both unlabeled rat and ovine PRL but not by several other polypeptide hormones. Scatchard analysis of the binding revealed the presence of the binding sites with low capacity and high affinity for rat ligand. Ovariectomy markedly decreased PRL binding in the hypothalamus; an even more pronounced decrease was found after hypophysectomy of female animals. A treatment with estradiol restored the PRL binding in the ovariectomized rats to above normal levels. These results of in vitro biochemical analysis together with the experimental modulation of hormonal status provide strong preliminary evidence for the presence of PRL binding sites in rat brain.

Animals↗
PubMed1989

S-adenosyl-L-methionine restores prolactin receptors in the aged rabbit brain.

The number of prolactin (PRL) receptors in the hypothalamus and substantia nigra of aged rabbits is significantly lower than the number measured in young animals. The treatment of aged rabbits for 30 days with S-adenosyl-L-methionine (SAM) restored the number of PRL binding sites to levels found in the hypothalamus and substantia nigra from young animals. We did not observe a clear-cut difference between the dissociation constants of untreated young, and untreated or SAM-treated aged rabbits, whereas the binding capacity varied. Moreover, in vitro addition of SAM to hypothalamic membranes from aged rabbits resulted in a significant increase in the number of binding sites. This in vitro effect was antagonized by S-adenosyl-L-homocysteine, a specific in vitro inhibitor of methyltransferase activity. The reduction in the number of PRL receptors is assumed to be related to the decrease in membrane fluidity induced by aging, while its increase after SAM treatment might be ascribed to the ability of this methyl donor to increase the fluidity of cell membranes by stimulating phospholipid synthesis.

Aging↗
PubMed1988

Regional distribution and species variation of prolactin binding sites in the brain.

The binding of 125I-labeled ovine prolactin (125I-oPRL) to membranes from different brain regions of pigeon, rabbit, rat, pig, calf, horse, and ewe was studied. The hypothalamus from rabbit, pig, horse, and pigeon showed a low but specific binding for 125I-oPRL clearly different from the other brain regions examined (cortex and cerebellum), whereas in the brain from rat, calf, and ewe the binding was very small and quite uniform in the various regions. Also the membranes from choroid plexus of rabbit, pig, calf, and horse showed an evident specific binding for prolactin. The binding of 125I-oPRL to hypothalamus and choroid plexus membranes from rabbit and horse was inhibited in a dose-dependent manner by unlabeled oPRL and hGH but not by many other polypeptide hormones. Scatchard analysis of the binding revealed the presence of binding sites with low capacity and high affinity for ovine ligand.

Animals↗
PubMed1988

Phosphatidylserine activity on prolactin brain receptors of aged rabbits.

1. PRL receptors in the hypothalamus and substantia nigra of aged rabbits (28-month-old) are significantly reduced in comparison with young rabbits (6-month-old). 2. Repeated treatments with BC-PS are able to gradually increase the PRL receptor number both in hypothalamus and nigra. However only after 30 days of treatment the binding reaches the mean values observed in young rabbits. 3. Aged rabbits showed an evident increase in PRL plasma levels in comparison with young animals. In BC-PS treated animals this increase was not more apparent. Moreover in young rabbits treated with BC-PS an evident decrease in basal PRL plasma levels was observed.

Adrenal Glands↗
PubMed1987

Prolactin binding sites in human erythrocytes and lymphocytes.

Specific binding sites for prolactin (PRL) have been studied in human peripheral lymphocytes and erythrocytes of normal adult volunteers and of term cord bloods. In erythrocytes from healthy adult subjects of both sexes a very low specific binding of 125I-human PRL was found (0.24%), whereas a higher binding was found in term cord blood (1.1%). The binding was hormone specific, the binding capacity was 2.6 fmol/4 X 10(9) cells and the Kd was 3.4 X 10(-10) M. In lymphocytes of both adults and term cord bloods an evident specific binding was observed (male adults: 1.6%; female adults: 1.7%; cord blood: 1.8%). The binding was specific for lactogenic hormones and the binding capacity was 3.7 fmol/2 X 10(6) cells and the Kd was 3.9 X 10(-10) M. The presence of specific binding sites for PRL on human erythrocytes and lymphocytes could be used to study PRL binding on blood cells of patients in different physiological or pathological situations.

Adult↗
PubMed1986

Effects of sustained hyperprolactinemia induced by chronic treatment with domperidone on central dopaminergic systems in the rat.

Chronic treatment with Domperidone (DOM) had no effect on basal prolactin (PRL) secretion or basal levels of Dopamine (DA) metabolites in basal hypothalamus and striatum as compared with the vehicle treated rats. Animals chronically treated with DOM did not present tolerance to a challenge dose of Haloperidol (HAL) and DOM either measuring PRL secretion or striatal DA metabolite levels. The PRL-induced increase in hypothalamic 3,4-dihydroxyphenylacetic acid (DOPAC) was reduced. These results were accompanied by no change at striatal DA receptors, a slight reduction in density-affinity at hypothalamic DA receptors but clear-cut modification in pituitary DA receptors with the appearance of a high affinity-low capacity binding sites. It can be surmised that sustained hyperprolactinemia may induce tolerance in hypothalamic Tuberoinfundibular (TIDA) neurons involved in the inhibitory control of PRL secretion and a change in the kinetic properties of pituitary DA receptors, but it does not consistently affect the activity of the nigro-striatal DA system.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

Further evidence for the presence of specific binding sites for prolactin in the rabbit brain. Preferential distribution in the hypothalamus and substantia nigra.

In the present research we have extended our work on the presence of binding sites for prolactin in the rabbit brain focusing our attention on the brain areas with high dopamine cell bodies density. Among these areas the hypothalamus showed the highest specific binding of labeled ovine prolactin (oPRL). Clearly detectible specific binding was observed also in substantia nigra, whereas in other brain regions the specific binding was very small, except for the striatum where a low but not negligible binding was found in female rabbits. The binding of 125I-oPRL showed a hormonal specificity and Scatchard analysis of the binding showed no clear difference in dissociation constant (Kd) between hypothalamus, nigra and striatum.

Animals↗
PubMed1985

Drug-induced membrane modifications differentially affect prolactin and insulin binding in the mouse liver.

Modifications in prolactin and insulin specific binding in the mouse liver induced by repeated administrations of ovine prolactin (oPRL) or indomethacin were studied. oPRL induced a dose-dependent and reversible increase of prolactin binding capacity. No change was observed in dissociation constant values. Conversely, insulin binding capacity to the same liver membranes was not modified by the treatment with oPRL. The increase in the binding induced by oPRL was not influenced by cycloheximide and it is therefore not dependent on protein synthesis. On the other hand, indomethacin caused a dose-dependent inhibition of prolactin binding capacity, without changes in dissociation constant values. The inhibitory effect was specific since at the doses used insulin binding to the same membranes was not affected. When indomethacin treatment was associated to oPRL administration it was able to counteract the increase in binding capacity caused by oPRL, even at doses ineffective in reducing the binding in non oPRL-treated mice. Our results suggest that drug-induced membrane modifications can selectively affect prolactin receptors and could consequently modify the ability of the target cell to respond to different physiological or pharmacological situations.

Animals↗
PubMed1984

Presence and characterization of prolactin receptors in human benign breast tumours.

Prolactin receptors have been determined in 64 benign breast tumours. A specific binding of 0.5% or more (with a range of 0.5-3.3%) was found in 34.4% of the cases and was considered prolactin-receptor-positive. The binding was found to be specific only for lactogenic hormones. By Scatchard analysis the dissociation constant was 2.55 X 10(-10) mol/l and the binding capacity was 4.6 fmol/mg protein.

Adenofibroma↗