Biomedical subjects

A Merante

Publications and source records attributed to A Merante.

5 recordsLinked to original sources

PubMed1999

Treatment with 6-hydroxydopamine in planaria (Dugesia gonocephala s.l.): morphological and behavioral study.

Morpho-functional and behavioral effects of exposure to 6-hydroxydopamine (OHDA)-HCI (24 microg/ml per day for 24 h and 7 days) were studied in planarias (Dugesia gonocephala s.l.). Exposure to 6-OHDA-HC1 for 24 h produced hypokinesia of the specimens. These behavioral changes were more pronounced, leading to complete immobility, after 7 days of exposure to the neurotoxin. Moreover, specimens exposed to 6-OHDA-HCI for 24 h and 7 days failed to show any behavioral response to nomifensine, thus furnishing evidence of the damage of presynaptic dopamine terminals. Exposure to 6-OHDA-HCl for 24 h significantly reduced cathecolamine content in neuropil region, as demonstrated by histochemistry, and electron-dense presynaptic vesicles, as observed on electron microscopy examination. All these alterations were significantly more pronounced and were accompanied by swelling and strong increase of electron-density in cytoplasm of numerous neurons after exposure to the neurotoxin for 7 days. This appears to be the first demonstration of the neurotoxic effects of 6-OHDA-HCI in flatworms.

Animals↗

PubMed1999

Opioid-dopamine interaction in planaria: a behavioral study.

The behavioral response of planaria to the exposure to selective opioid agonists was studied. The mu agonist [d-ala2, N-methyl-Phe4,Gly5-ol]enkephalin (DAMGO) and the 6 agonist [D-Pen2, D-Pen5]enkephalin (DPDPE) failed to alter motor activity at all doses tested. Low doses of the selective kappa agonist (+/-)-trans-U-50-trans-3,4-dichloro-N-methyl-N[2-(1-pyrrodinyl)-cyclohexyl]benzene acetamide methasulphonate (U50, 488) and bremazocine-HCl increased motor activity leading to C-like position (CLP) and screw-like hyperkinesia (SLH). These changes were identical to those seen previously with the exposure to D2 or D1 dopamine receptor agonists, respectively. Higher doses of kappa agonists produced the enhancement of CLP and SLH together with robust snake-like movements (SLM). This latter response, that was typical of stimulation of kappa opioid receptors, was blocked by co-exposure to naloxone or the selective kappa antagonist Nor-binaltorphimine (Nor-BNI). Finally, co-exposure to sulpiride or SH-23390 respectively blocked the CLP or SLH response produced by U50,488 or bremazocine. Our data indicate the presence of kappa opioid receptors in planaria and suggest the functional interaction between the opioid and dopamine system in this simple animal model.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1997

Nitric oxide involvement in Hydra vulgaris very primitive olfactory-like system.

Hydra feeding response is a very primitive olfactory-like behavior present in a multicellular organism. We investigated the role of nitric oxide (NO) in the induction and control of hydra feeding response. Under basal conditions, hydra specimens produce detectable amounts of nitrite (NO2-), the breakdown product of NO. When hydra were incubated with reduced glutathione (GSH), the typical activator of feeding response, an increase of basal NO production was observed. This effect was inhibited by glutamic or alpha-aminoadipic acids, two GSH antagonists, which block GSH-induced feeding response, and by the NO synthase (NOS) inhibitor L-NAME. Moreover, we found that hydra possess a calcium-dependent (but calmodulin-independent) NOS isoform. By using exogenous NO donors and NOS inhibitors, we demonstrated that NO stimulus can participate both in triggering tentacular movements and in recruiting neighbor tentacles during hydra feeding response. By using dbt2-cGMP, an analog to cGMP, we observed that the NO effect was independent of cGMP pathway. Our results strongly implicate NO involvement in hydra very primitive feeding behavior, thus confirming its preservation throughout evolution.

Animals↗

PubMed1997

Effects of cocaine treatment on the nervous system of planaria (Dugesia gonocephala s. l.). Histochemical and ultrastructural observations.

Acute high dose treatment with cocaine in planaria has been shown to produce hyperkinesia followed by immobilization, thus suggesting progressive neuronal dopamine (DA) depletion. On the contrary, treatment with low doses of cocaine inhibits motor activity in planaria, without producing hyperkinesias. Here we investigated the morpho-functional changes of the DA presynaptic terminals following cocaine treatment in planaria (acute high dose and chronic low dose). Neuronal DA content was determined by means of histochemical methods, and nerve cell ultrastructure was examined by electron microscopy. The effects of cocaine were compared to those of L-dopa, reserpine (used as positive and negative controls, respectively) and normal untreated specimens. Presynaptic vesicles and DA content were significantly reduced by chronic low-dose cocaine treatment. These effects were even more robust when the drug was acutely administered at high dose. Thus, depletion of DA vesicles is produced by cocaine in planaria, as well as in mammals. The behavioral effects of chronic low-dose treatment with cocaine, however, suggest that the drug acts not only as a DA reuptake blocker, but also as a direct agonist on presynaptic DA receptors. Acute high-dose administration of cocaine also produced signs of neuronal suffering, thus providing evidence for a direct neurotoxic effect of the drug.

Animals↗

PubMed1996

[Sexuality of elderly women].

Physiological aging in older women it is not necessarily the cause of a change in their sexual attitudes. The organic changes, during concomitant illness, is often known to be the cause of sexual dysfunction, when present. Psychosocial factors are also very important in determining sexual dysfunction. Successful management of sexual dysfunction in older women is totally dependent on clinical history, physical examination of genitalia, personal interview. A multidisciplinary team approach is required for otimal management of sexual problems in elderly women.

Age Factors↗