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Biomedical subjects

G Giammona

Publications and source records attributed to G Giammona.

At least 55 records · Page 3Linked to original sources
PubMed1983

[Neuroendocrine modulation of haloperidol-induced catalepsy].

Evidence has been accumulated implicating sex hormones as possible modulators of extrapyramidal motor function. In the present study we have investigated the effects of estrogens, progesterone, testosterone, prolactin and calcitonin on behavioral parameters related to nigro-striatal dopaminergic system, such as haloperidol-induced catalepsy in male rats. It was found that 7-days estradiol benzoate treatment (5 micrograms/rat/day) significantly increases haloperidol-induced catalepsy, suggesting a possible antidopaminergic activity of estrogens. On the other hand, prolactin facilitates nigro-striatal dopaminergic transmission. Interestingly, 7 day treatment with medroxy-acetate progesterone (MAP, 5 mg/Kg, i.p.) brings about a trend to a decrease in haloperidol-induced catalepsy, while no significantly effect was observed following acute MAP administration at the same dose. So, it is tempting to speculate that chronic progestinic treatment may result in an increase in dopaminergic tonus. Testosterone, acutely administered (5mg/kg.s.c.) induces changes similar to those observed following progesterone administration. Finally, also calcitonin is able to influence haloperidol-induced catalepsy by markedly increasing it.

Androgens↗
PubMed1983

Antidyskinetic properties of estrogens.

There is mounting evidence that several gonadal hormones may influence central nervous system. In particular, it has been found that estrogens display an antidopaminergic activity at the level of the extrapyramidal motor system. In this line we have investigated behavioral and biochemical parameters related to nigrostriatal DAergic function. Results obtained further indicate that estrogens display an antidopaminergic activity, by acting on nigrostriatal postsynaptic DAergic receptors. These results may suggest an antidyskinetic activity of estrogens.

Animals↗
PubMed1982

Comparative effects of estrogens and prolactin on nigral and striatal GAD activity.

The comparative effects of a 10 day estrogen treatment and estrogen independent hyperprolactinemia on nigral and striatal glutamic acid decarboxylase (GAD, EC 4.1.1.15) activity were investigated in male rats. Data obtained show that estrogen treatment decreases GAD activity in substantia nigra, while an increase was observed in conditions of hyperprolactinemia induced by adenohypophysis homograft or acute and chronic sulpiride injection. The possibility of an opposite modulation of strio-nigral GABAergic system by estrogens and prolactin is suggested.

Animals↗
PubMed1981

[Effects of different doses of apomorphine on the glutamate decarboxylase activity of the substantia nigra and the medial basal hypothalamus].

The activity of gamma-aminobutyric acid (GABA) synthesizing enzyme glutamic acid decarboxylase (GAD, EC 4.1.1.15) was assayed in the rat substantia nigra (SN) and medial basal hypothalamus (MBH) following systemic injection of different doses of the dopamine receptor agonist apomorphine. In SN, the highest dose of apomorphine (1000 micrograms/kg) causes an increase of the GAD activity whilst an opposite effect is observed with the lowest dose (35 micrograms/kg). Results obtained in SN are in accordance with previous neurochemical and behavioural data suggesting an opposite action of high (500 micrograms/kg) and low doses (100 micrograms/kg) of apomorphine in nigro-striatal system, probably due to the existence of two classes of dopamine receptors, i.e. classical postsynaptic dopamine receptors and presynaptic inhibitory dopamine autoreceptors. In MBH, the evidence for similar effects of low and high doses of apomorphine (the decrease of GAD activity) may suggest that, as already reported, at this level only one class of dopamine receptors is present.

Animals↗
PubMed1981

[Hyperprolactinemia and catalepsy induced by haloperidol].

The effect of endogenous hyperprolactinemia induced by pituitary transplantation under the kidney capsule on haloperidol induced catalepsy was evaluated in male Wistar rats treated with two doses of the drug (500 gamma/kg; 2 mg/kg i.p.). Rats of 220 +/- 30 g received intraperitoneal injection of haloperidol. Every five minutes following drug administration the rats were assessed for catalepsy by placing the forepaw on a horizontal bar, and observed for two minutes. Data obtained show that hyperprolactinemia potentiates the cataleptic score in rats treated with dose of 500 gamma/kg i.p., while no significant difference was observed between hyperprolactinemic rats and control rats, at the dose of 2 mg/kg i.p. of haloperidol.

Animals↗
PubMed1981

Effects of chronic haloperidol and sulpiride treatment on rat nigral GABA content.

The effects of chronic haloperidol and sulpiride treatment on nigral GABA content were investigated in rats. Chronic sulpiride treatment is capable of inducing an increase in nigral GABA content whilst no significant effect is observed following chronic haloperidol treatment at the doses used. The different effects of haloperidol and sulpiride on nigral GABA content were related to the different neuropharmacological spectrum of the two drugs.

Animals↗
PubMed1981

Effects of different doses of apomorphine on GAD activity in rat substantia nigra.

The effects of different doses of the dopamine (DA) receptor agonist apomorphine on the activity of the gamma-aminobutyric acid (GABA)-synthesizing enzyme glutamic acid decarboxylase (GAD, EC 4.1.1.15) were investigated in rat substantia nigra in comparison with haloperidol and sulpiride, two DA receptor blocking agents. Results obtained show that low doses (10,35 microgram/kg, s.c.) of apomorphine induce a decrease in nigral GAD activity whilst an opposite effect is observed with the highest dose (1000 microgram/kg, s.c.). No significant change is observed following injection of the intermediate doses (100 and 500 microgram/kg, s.c.). Moreover, sulpiride at the dose used (2 mg/kg, i.p.) induces an increase in GAD activity whilst no effect follows systemic injection of the same dose of haloperidol. The results are discussed in light of recent neurochemical and behavioral data.

Animals↗
PubMed1981

Comparative effects of chronic haloperidol and sulpiride treatment on nigral and striatal GABA content.

Nigral and striatal GABA contents were assayed in male rats treated chronically with haloperidol or sulpiride, two dopamine-receptor blocking agents that have different neuropharmacological spectra in regard to their biochemical, behavioural, and clinical properties. No great difference was observed between the chronic effects of haloperidol and sulpiride on nigral and striatal GABA content. However, low doses (30 micrograms/kg, intraperitoneally) of the dopamine-receptor agonist apomorphine, injected 12 h after the discontinuation of chronic haloperidol or chronic sulpiride treatment, induced opposite changes in nigral GABA levels suggesting the existence of a different "status" of the dopamine receptors during the 12 h-period following the withdrawal of haloperidol or sulpiride.

Animals↗
PubMedDate not supplied

Polymeric prodrug for release of an antitumoral agent by specific enzymes.

The clinical usefulness of antitumor chemotherapy has been strongly limited by the lack of specificity of most anticancer drugs, which act also against healthy cells. The aim of this work was to design, synthesize, and evaluate a macromolecular prodrug of Cytarabine, a known antitumor drug, which is a specific substrate for plasmin enzyme whose concentration is high in various kinds of tumor mass as a result of plasminogen activator secretion. alpha,beta-Poly(N-hydroxyethyl)-DL-aspartamide (PHEA), a known synthetic and biocompatible polyamino acid, was used as a drug carrier, and Cytarabine was linked to PHEA by D-Val-Leu-Lys spacer synthesized beginning from Cbz-D-Val-LeuOH dipeptide and N6-CbzLys methyl ester. The content of Cytarabine in the purified PHEA-D-Val-Leu-Lys-Cytarabine conjugate was equal to 3% w/w. In vitro experiments in the presence of plasmin evidenced the ability of this enzyme to strongly increase drug release from the macromolecular prodrug, as well as plasma incubation shows high stability of drug-polymer linkage. The direct linkage of Cytarabine to PHEA was also performed and, like PHEA-D-Val-Leu-Lys-Cytarabine conjugate, the obtained PHEA-Cytarabine conjugate showed high stability in plasma, but no release of Cytarabine was revealed in the presence of plasmin.

Antimetabolites, Antineoplastic↗
PubMedDate not supplied

Beads of acryloylated polyaminoacidic matrices containing 5-Fluorouracil for drug delivery.

Spherical polymeric microparticles have been prepared by a reverse phase suspension polymerization technique. The starting polymer was alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA), partially derivatized with glycidylmethacrylate (GMA). PHEA-GMA copolymer (PHG) was crosslinked in the presence of N,N'-dimethylacrylamide (DMAA) or N,N'-ethylenebisacrylamide (EBA). 5-fluorouracil was incorporated into PHG-DMAA or PHG-EBA beads both during and after the crosslinking process. Swelling studies revealed a high affinity toward aqueous medium, influenced by the presence of 5-fluorouracil. The in vitro release study showed that the release rate depends on the chemical structure of the beads and the procedure adopted to incorporate 5-fluorouracil into the microparticles.

Acrylates↗
PubMedDate not supplied

Novel cationic copolymers of a polyasparthylhydrazide: synthesis and characterization.

Alpha,beta-poly(asparthylhydrazide) (PAHy), a water soluble synthetic polymer, was functionalized by using EDCI chemistry with 3-(carboxypropyl)trimethyl-ammonium chloride (CPTACl) obtaining carboxypropyltrimethyl ammonium copolymers (PAHy-CPTA). Three PAHy-CPTA copolymers at increasing derivatization degrees (38%, 48%, 58%) were chosen for subsequent investigations. The capability of these copolymers to bind, neutralize, and protect DNA against degradation by DNase II was evalued by gel retardation assay and DNA degradation test at pH 5.5. Zeta potential measurements show that all studied polymers are able to neutralize the anionic charge of DNA at polymer/DNA weight ratio in the range of 0.8/1-5/1. Polyplex dimensional distribution analyses in bistilled water, saline solution NaCl 0.9%, and HEPES pH 7 show that polyplex size is strongly affected by both presence and type of electrolyte and with time incubation.

Carbodiimides↗
PubMedDate not supplied

Preparation and characterization of solid lipid nanoparticles containing cloricromene.

This article describes the development of solid lipid nanoparticles (SLN) as colloidal carriers for cloricromene. Nanoparticles were prepared by the microemulsion or precipitation technique. In vitro drug release profile from SLN was studied under various experimental conditions mimicking some body fluids. The drug release rate of drug at pH 7.4 and human plasma is high. In plasma, after 15 min, about 70% of drug was released. The cloricromene that was not released within 4 hr was found in the SLN. This result suggests that this colloidal system could be useful for targeted drug delivery to the central nervous system after intravenous administration.

Chromonar↗