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R Di Carlo

Publications and source records attributed to R Di Carlo.

At least 19 recordsLinked to original sources
PubMed1996

The effect of age and sex on the expression of prolactin binding activity in the chicken bursa of Fabricius.

The binding of 125I-labeled prolactin (PRL) to membranes from the bursa of Fabricius of male and female chicks of different ages (15-30-45 and 60 days) was studied. In male chicks the binding was very low in 15 day-old animals and slightly increased in more aged animals. In female chicks the binding was more evident in young animals and decreased in 60 day-old animals. The binding showed a hormonal specificity and Scatchard analysis of the binding revealed the presence of binding sites with low capacity and high affinity. The presence of PRL receptors in the bursa of the chick, a structure that confers immunological competence to birds, gives further support to the involvement of the hormone in the immune processes.

Aging↗
PubMed1996

Recombinant human prolactin induces protection against Salmonella typhimurium infection in the mouse: role of nitric oxide.

In the present study, we demonstrated that repeated treatment with recombinant human prolactin (rhPRL) protected mice against Salmonella typhimurium infection. The protective activity was statistically significant, dose-dependent and present only when rhPRL treatments were performed before the infection. This activity was probably related to the observed increases in phagocytosis and intracellular killing of peritoneal macrophages induced by the hormonal treatment. The number of peripheral leukocytes was not modified, excluding a mobilization of cells from other compartments. A decrease in the mortality rate after challenge was also observed in mice treated with the monoclonal antibody anti-PRL receptor U5, confirming that the protective activity was associated with receptor activation. Our studies also suggest that nitric oxide (NO) production was involved in the protective effect of rhPRL since pre-treatment of the animals with L-NAME, an inhibitor of NO-synthase, was able to completely revert the protective activity, whereas D-NAME, the inactive D-isomer, was without effect.

Animals↗
PubMed1996

Effect of L-alpha glycerylphosphorylcholine on muscarinic receptors and membrane microviscosity of aged rat brain.

1. Old rats showed a significant decrease in the number of muscarinic M(1) receptors and a significant increase in membrane microviscosity in the striatum and hippocampus as compared to young animals. In contrast, no significant changes in the density of muscarinic M(2) receptors were observed with aging. 2. Chronic treatment of aged rats with L-alpha-glycerylphosphorylcholine (L-alpha-GPC) restored the number of M(1) receptors to levels found in the striatum and hippocampus from young animals. The same treatment to aged rats partially restored membrane microviscosity in both regions studied and hence increased membrane fluidity. 3. None of the major metabolites of L-alpha-GPC (choline, glycerophosphate or phosphorylcholine) was able to restore the number of striatal and hippocampal M(1) sites and membrane microviscosity of aged rats, neither did any of these treatments (including treatment with L-alpha-GPC) modify the level of M(1) receptors and microviscosity values in young rats.

Aging↗
PubMed1995

Regulation of prolactin receptor mRNA expression in peripheral lymphocytes in rats in response to changes in serum concentrations of prolactin.

In the present study we have evaluated the absolute number of the two forms of prolactin (PRL) receptor mRNA in rat peripheral blood lymphocytes and the modulation of receptor mRNA induced by changes in serum levels of endogenous PRL or by administration of ovine PRL. Lymphocytes expressed low levels of both forms of PRL receptor transcripts. Repeated treatments with ovine PRL significantly reduced levels of mRNA encoding the long form PRL receptor, whereas expression was markedly increased by repeated doses of bromocriptine. In contrast, the mRNA level of short form PRL receptor was unchanged by both treatments. The expression of long form transcripts was also markedly decreased in lymphocytes from pituitary-grafted rats. Therefore it appears that in rat peripheral lymphocytes PRL has a negative effect on the expression of its own receptor.

Animals↗
PubMed1995

Effect of prolactin, rIFN-gamma or rTNF-alpha in murine toxoplasmosis.

Mice lethally infected with T. gondii and treated with prolactin (PRL), recombinant interferon gamma (rIFN-gamma) or recombinant tumour necrosis factor (rTNF-alpha) were protected against death, as compared to untreated controls. The protective effect of PRL (0.5-2 mg/kg/twice daily for 12 days) was dose dependent and statistically significant (P < 0.001). The survival was 50% or 40% in mice that received doses of 1 x 10(4) U of rIFN-gamma or 4 x 10(4) U of rTNF-alpha at -2, 0, +2 days before and after infection (P < 0.0001). An increase of time to death, up to 60 days after challenge, and of survival rate (50% up to 70%) were observed in animals treated with PRL in combination with either rTNF-alpha or rIFN-gamma, compared to those that received treatments with the same therapeutic agents alone; however the differences were not statistically significant. In addition, a slight synergistic effect on brain cyst formation, with lower number of Toxoplasma cysts, was observed in mice treated with PRL plus TNF-alpha (P < 0.01), compared with animals that received rTNF-alpha alone (P < 0.05). These data suggest that PRL can regulate in vivo endogenous TNF-alpha production in the cytokine cascade. We conclude that prolactin may play an important role in modulating the host's immune defence against T. gondii opportunistic infection.

Adult↗
PubMed1994

Modulation of prolactin receptors in the rat hypothalamus in response to changes in serum concentration of endogenous prolactin or to ovine prolactin administration.

Specific binding of 125I-labeled rat prolactin (125I-rat PRL) to hypothalamic membranes was studied in Sprague-Dawley rats after ovine PRL administration and in relation to rat PRL serum variations induced by ectopic pituitary implants or by drugs which stimulate (domperidone) or inhibit (bromocriptine) PRL release. Repeated treatments with ovine PRL markedly increased specific binding values of 125I-rat PRL to hypothalamic membranes of female rats. Repeated treatments with domperidone also increased specific PRL binding in the hypothalamus. This effect was associated with an increase in PRL serum levels. Similar results were obtained in male rats after renal pituitary implants which resulted in a state of chronic hyperprolactinaemia. In contrast, a subchronic treatment with bromocriptine decreased specific PRL binding in the hypothalamus and concomitantly caused a sharp reduction in PRL serum levels. Scatchard analysis of data obtained from competition curves showed that the variations in the level of PRL binding to hypothalamic membranes were related to the number of PRL binding sites but not to the dissociation constant (Kd), which was unaffected by different treatments or by pituitary implantation. These results demonstrate a correlation between circulating concentrations of PRL and number of its receptors in the rat hypothalamus and give further support to the hypothesis that these binding sites may have a specific functional role in regulating the homeostasis of pituitary PRL secretion.

Animals↗
PubMed1993

Prolactin protection against lethal effects of Salmonella typhimurium.

The immunoregulatory role of prolactin (PRL) has been well established. In order to clarify if the hormone is also able to stimulate a protective activity against pathogens-induced infections we have studied the modifications of the infective capacity of Salmonella typhimurium induced in mice by repeated treatments with ovine PRL. A significant dose-dependent reduction in the mortality rate was observed in comparison to controls. This activity is probably related to the observed increases in phagocytosis and intracellular killing of the peritoneal macrophages and chemotaxis of the peritoneal granulocytes induced by the hormonal treatment. On the contrary, the number of leukocytes in blood was not modified by PRL treatment excluding a mobilization of cells from other districts. Our findings confirm the existence of a linkage between the neuroendocrine and immune systems suggesting a possible role for PRL in the regulation of non-specific immune response.

Animals↗
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↗