Peculiar response to methylphenidate in adolescent compared to adult rats: a phMRI study.

RATIONALE: Adolescent rodents differ markedly from adults in several neuro-behavioural parameters. Moreover, 'paradoxical' responses to psychostimulants have been reported at this age. OBJECTIVES: Thus, we investigated the responses of adolescent (post-natal day, PND, 34 to 43) and adult (PND >60) Sprague-Dawley male rats to the psychostimulant drug methylphenidate (MPH). We used pharmacological magnetic resonance imaging (phMRI) performed at 4.7 T under isoflurane anaesthesia. Following anatomical MRI, axial gradient echo images were collected continuously. After baseline recording (32 min), animals received MPH (0 or 4 mg/kg i.p.) and were recorded for further 32 min. RESULTS: Region-specific changes in the blood-oxygenation level dependent (BOLD) signal were evident as a function of age. As expected, among adults MPH induced an increase of BOLD signal in nucleus accumbens (NAcc) and prefrontal cortex (PFC), with no effects in the hippocampus (Hip). Notably, among adolescents, MPH induced a marked and generalised decrease of BOLD signal, which occurred earlier in NAcc and PFC whilst being delayed in the Hip. Any bias in BOLD responses was excluded by the measurement of physiological parameters. CONCLUSIONS: The present findings highlight the utility of phMRI in animal models. The peculiar negative BOLD effect found in adolescent rats may be suggestive of a reduced cerebro-vascular feedback and/or an increased MPH-induced neuronal activation. Data are relevant for a better understanding of brain/behavioural regulation during adolescent development. Moreover, a greater understanding of the differences between adult and adolescent drug responses will aid in the development of a more appropriate age-specific treatment strategy.

Antisense versus proopiomelanocortin mRNA reduces vascular risk in a murine model of type-2 diabetes following stress exposure in early post-natal life.

Mechanisms of vascular complications in type-2 diabetes patients and animal models are matter of debate. We previously demonstrated that a double-stress model applied to male mice during nursing period produces enduring hyperfunction of endogenous opioid and adrenocorticotropin (ACTH)-corticosteroid systems, accompanied by type-2 diabetes-like alterations in adult animals. Administration of the opioid receptor antagonist naloxone, or of an antisense oligodeoxynucleotide versus proopiomelanocortin mRNA, capable to block the pro-opiomelanocortin-derived peptides ß-endorphin and ACTH, selectively prevent these alterations. Here, we investigated alterations produced by our stress model on aorta endothelium-dependent relaxation and contractile responses. Mice, stressed during nursing period, showed in the adulthood hormonal and metabolic type-2 diabetes-like alterations, including hyperglycemia, increased body weight and increased plasma ACTH and corticosterone levels. Ex vivo isolated aorta rings, gathered from stressed mice, were less sensitive to noradrenaline-induced contractions versus controls. This effect was blocked by nitric-oxide synthase-inhibitor l-N(G)-nitroarginine added to bath organ solution. Aorta rings relaxation caused by acetylcholine was enhanced in stressed mice versus controls, but following treatment with the nitric-oxide donor sodium nitroprusside, concentration-relaxation curves in aorta from stressed groups were similar to controls. Therefore, vascular response alterations to physiologic-pharmacologic stimuli were apparently due to nitric-oxide hyperfunction-dependent mechanisms. Aorta functional alterations, and plasma stress hormones enhancement, were prevented in mice stressed and treated with antisense oligodeoxinucleotide, addressed to reduce ACTH- and corticosteroid-mediated hyperfunction. This study demonstrates the key role of ACTH-corticosteroid axis hyperfunction for the triggering of vascular conditions in male adult rodents following postnatal stress in a type-2 diabetes model.

Endothelium-dependent noradrenergic hyperresponsiveness induced by thapsigargin in human saphenous veins: role of thromboxane and calcium.

To further investigate the mechanisms which regulate sympathetic vascular tone, we studied the effects of the sarcoplasmic reticulum Ca(2+)-ATPase inhibitor, thapsigargin, on the vasoconstriction induced by transmural nerve stimulation and noradrenaline in superfused human saphenous vein rings. The contractions induced by both transmural nerve stimulation and noradrenaline were potentiated by thapsigargin in endothelium-intact, but not in endothelium-denuded vessels. This potentiation was unaffected by the non-selective endothelin ET(A/B) receptor antagonist, Ro 47-0203 (4-tert-Butyyl-N-[6-(2-hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-2,2'-bipyrimidin-4yl]benzene sulfonamide), or by the nitric oxide (NO) synthase inhibitor, L-NNA (N(omega)-nitro-L-arginine), but was inhibited by the thromboxane A(2) receptor antagonist, Bay u3405 (3(R)-[[(4-flurophenyl) sulphonyl]amino-1,2,3,4-tetrahydro-9H-carbazole-9-propanoic acid]) or by the thromboxane A(2) synthase inhibitor, UK 38485 (3-(1H-imidazol-1-yl-methyl)-2-methyl-1H-indole-1-propanoic acid). Moreover, the thapsigargin-induced noradrenergic hyperresponsiveness, as well as that produced by subthreshold concentrations of the thromboxane A(2) mimetic, U 46619, were blocked by the Ca(2+) channel antagonist, verapamil. In conclusion, our results indicate that thapsigargin enhances the contractions produced by sympathetic nerve stimulation in human saphenous vein rings through the endothelial release of thromboxane A(2) that potentiates the vasoconstriction induced by the noradrenergic mediator with a verapamil-sensitive mechanism.

The role of the Istituto Superiore di Sanità as the competent authority for Phase I trials in the translation of advanced therapies.

Advanced therapy medicinal products (ATMP) can offer new, effective therapeutic options for the treatment of severe illnesses, including cancer, neurodegenerative and cardiovascular diseases. Translation of advanced therapies to the clinic has been slow despite significant academic research from academia and foundations. The implementation of 2001/20 Directive in Italy established that the development of an ATMP should follow the GXP rules - good manufacturing practice (GMP) for production, good laboratory practice (GLP) for non clinical safety studies and good clinical practice (GCP) for clinical trials. The high costs of GCP application and the needs for GMP facilities are perceived as the most important bottlenecks for the development of ATMP. Here it is pointed out that a strategic cooperation between different actors (academia, industry and experts in regulatory issues) is strongly needed. In particular, it is highlighted that the Istituto Superiore di Sanità, as the competent authority for the authorization of Phase I clinical trials, has a specific responsibility in fostering the translation of safe and effective therapies for human diseases.