Efficacy of the MCHR1 antagonist N-[3-(1-{[4-(3,4-difluorophenoxy)phenyl]methyl}(4-piperidyl))-4-methylphenyl]-2-methylpropanamide (SNAP 94847) in mouse models of anxiety and depression following acute and chronic administration is independent of hippocampal neurogenesis.

Melanin-concentrating hormone (MCH) is a hypothalamic neuropeptide that plays a role in the modulation of food intake and mood. In rodents, the actions of MCH are mediated via the MCHR1 receptor. The goal of this study was to investigate the effects of acute (1 h) and chronic (28 days) p.o. dosing of a novel MCHR1 antagonist, N-[3-(1-{[4-(3,4-difluorophenoxy)-phenyl]methyl}(4-piperidyl))-4-methylphenyl]-2-methylpropanamide (SNAP 94847), in three mouse models predictive of antidepressant/anxiolytic-like activity: novelty suppressed feeding (NSF) in 129S6/SvEvTac mice and light/dark paradigm (L/D) and forced swim test (FST) in BALB/cJ mice. A significant increase in the time spent in the light compartment of the L/D box was observed in response to acute and chronic treatment with SNAP 94847. An anxiolytic/antidepressant-like effect was found in the NSF test after acute and chronic treatment, whereas no effect was observed in the FST. Because neurogenesis in the dentate gyrus has been shown to be a requirement for the effects of antidepressants in the NSF test, we investigated whether neurogenesis was required for the effect of SNAP 94847. We showed that chronic treatment with SNAP 94847 stimulated proliferation of progenitors in the dentate gyrus. The efficacy of SNAP 94847 in the NSF test, however, was unaltered in mice in which neurogenesis was suppressed by X-irradiation. These results indicate that SNAP 94847 has a unique anxiolytic-like profile after both acute and chronic administration and that its mechanism of action is distinct from that of selective serotonin reuptake inhibitors and tricyclic antidepressants.

Reversibility of thymulin production impairment by L-arginine supplementation in mice exposed to inorganic mercury.

Immunotoxicological effects fo mercury on peripheral immune system are known. We had previously in vitro found that mercuric chloride inhibits thymulin production in mouse thymus cultures at concentrations as low as 10(-8) M. In this study, thymus efficiency, assessed as production of active and total thymulin, was evaluated in vivo using young mice that were injected sc every 3 days for 4 weeks with saline containing mercuric chloride at different concentrations (0 -controls-, 0.001 or 1.0 mg HgCl2/kg body weight). The results show that both the doses are able to cause a significant reduction in active and total thymulin production. Since arginine enhances immune efficiency some of the animals also received a diet supplemented with arginine in order to evaluate a possible role of arginine during mercury intoxication. The data show that arginine has a protective effect on thymic endocrine efficiency. Mice, treated with the lowest dose of mercury and receiving and arginine supplemented diet, produced active and total thymulin like mercury untreated mice. Arginine is an aminoacid which may be found in various amounts in different foods, some foods are particularly rich in arginine i.e. peanuts, stock fish. We suggest that the daily arginine intake may account for individual susceptibility to the mercury-induced immunological effects which are found in mercury occupationally exposed workers.

Effect of Lactobacillus GG supplementation on antibiotic-associated gastrointestinal side effects during Helicobacter pylori eradication therapy: a pilot study.

BACKGROUND: One-week triple therapy is currently regarded as the reference of anti-Helicobacter pylori treatment. However, antibiotic-associated gastrointestinal side effects are among the major pitfalls of such regimens. Probiotic supplementation may be regarded as a therapeutic tool to prevent or reduce these troublesome drug-related manifestations. AIM: To determine whether the addition of the probiotic Lactobacillus GG to an anti-H. pylori standard triple therapy could help to prevent or minimize the occurrence of gastrointestinal side effects. METHODS: One hundred and twenty healthy asymptomatic subjects screened positive for H. pylori infection and deciding to receive eradication therapy were randomized either to 1-week pantoprazole (40 mg b.i.d.), clarithromycin (500 mg b.i.d.), tinidazole (500 mg b.i.d.) or to the same regimen supplemented with Lactobacillus GG for 14 days. Patients filled in validated questionnaires during follow-up to determine the type and severity of side effects and to judge overall tolerability. RESULTS: Bloating, diarrhea and taste disturbances were the most frequent side effects during the eradication week and were significantly reduced in the Lactobacillus GG-supplemented group (RR = 0.4, CI 0.2-0.8; RR = 0.3, CI 0.1-0.8; RR = 0.3, CI 0.1-0.7, respectively). The same pattern was observed throughout the follow-up period. Overall assessment of treatment tolerability showed a significant trend in favor of the Lactobacillus GG-supplemented group (p = 0.03). CONCLUSIONS: Lactobacillus GG supplementation beneficially affects H. pylori therapy-related side effects and overall treatment tolerance.

Reversibility of the thymic involution and of age-related peripheral immune dysfunctions by zinc supplementation in old mice.

With advanced ageing the zinc pool undergoes progressive reduction as shown by the low zinc plasma levels and the negative crude zinc balance, both in humans and in rodents. It has been suggested that such zinc deficiency might be involved in many age-related immunological dysfunctions, including thymic failure. The relevance of zinc for good functioning of the entire immune system is, at present, well documented. In particular, zinc is required to confer biological activity to one of the best-known thymic peptides, thymulin, which is responsible for cell-mediated immunity. In deep zinc deficiencies, in humans and other animals, the low thymulin levels are due not to a primary failure of the thymus, but to a reduced peripheral saturation of thymic hormones by zinc ions. In aged mice both a reduced peripheral saturation of the hormone and a decreased production by the thymus were present. Oral zinc supplementation in old mice (22 months old) for 1 month induced a complete recovery of crude zinc balance from negative (-1.82) to positive values (+1.47), similar to those of young animals (+1.67). A full recovery of thymic functions with a regrowth of the organ and a partial restoration of the peripheral immune efficiency, as measured by mitogen responsiveness (PHA and ConA) and natural killer cell (NK) activity, were observed after zinc supplementation. These findings clearly pin-point for relevance of zinc for immune efficiency and suggest that the age-related thymic involution and peripheral immunological dysfunctions are not intrinsic and irreversible events but are largely dependent on the altered zinc pool.

Role of the low zinc bioavailability on cellular immune effectiveness in cystic fibrosis.

An altered cellular immune response as a secondary phenomenon has been suggested to be probably involved in the bronchopulmonary infections by Pseudomonas aeruginosa in cystic fibrosis (CF). The difficulty to eradicate with modern anti-pseudomonal antibiotics the bronchopulmonary infections has led us to further investigate the possible existence of other cellular immune defects and their cause. Alterations in zinc turnover are present in CF. Zinc is relevant for good immune functioning. In particular, zinc is required to confer biological activity to thymulin (ZnFTS), a biochemically defined thymic hormone with a modulating action on cell-mediated immunity. The zinc-unbound form (FTS) is inactive and it can be unmasked by in vitro zinc addition to the plasma samples revealing the total amount of circulating thymulin (active + inactive). Marginal zinc deficiencies may prevent peripheral biological activation of active thymulin. Total zinc-saturable thymulin fractions in CF are similar to those observed in normal subjects, whereas the active quota is strongly reduced associated with concomitant high plasma levels of inactive thymulin compared to the values of healthy children (P < 0.01). A strict correlation exists between zinc and thymic hormone-saturable fraction (r = 0.87, P < 0.01) in CF. These findings suggest that the defect is not due to a thymic failure but to a reduced peripheral saturation of thymulin by zinc ions. This defect might depend on augmented plasma concentration of alpha 2-macroglobulin, which has a higher binding affinity for zinc than thymulin. T cell subsets are normal in CF. Reduced NK cell number and activity are present. Also, plasma IL-2 levels are reduced. The existence of positive correlations between zinc and IL-2 (r = 0.79, P < 0.01) and between zinc or active thymulin and NK activity (r = 0.70, P < 0.01 and r = 0.88, P < 0.01, respectively) suggest a close link among zinc failure, impaired IL-2 activity, low thymulin level, and reduced NK activity in CF patients with both normal and growth retardation. Although the role of NK cells is unknown in CF, a zinc supplementation, in order to induce a complete saturation of thymulin molecules, to correct some cellular immune defects and to improve the growth, may be suggested.

The immuno-reconstituting effect of melatonin or pineal grafting and its relation to zinc pool in aging mice.

It has been demonstrated that melatonin, the main neuro-hormone of the pineal gland, affects thymic functions and the regulation of the immune system. In addition, experimental evidences indicate that melatonin can modulate zinc turnover. The knowledge that with advancing age both melatonin and zinc plasma levels decline, and that zinc supplementation in old mice is able to restore the reduced immunological functions, has prompted investigations on the effect of chronic melatonin treatment or pineal graft in old mice on the age-related decline of thymic endocrine activity, peripheral immune functions and zinc turnover. Both melatonin treatment in old mice and pineal graft into the thymus of old mice correct the reduced thymic endocrine activity and increase the weight of the thymus and its cellularity. A restoration of cortical thymic volume, as detected by the percentage of tissue in active proliferation, is also observed in old mice after both treatments. Thymocyte CD phenotype expression is also restored to young values. At peripheral level, recovery of peripheral blood lymphocyte number and of spleen cell subsets, with increased mitogen responsiveness also occurs. Melatonin treatment or pineal graft induce also a restoration of the altered zinc turnover in aged mice with an increment of the crude zinc balance from negative (-1.6 microgram/day/mouse) to positive value (+1.2 microgram/day/mouse), similar to that one of young mice (+1.4 microgram/day/mouse). The reduced zinc plasma level is restored to normal values. These findings support the idea that the effect of melatonin on thymic endocrine activity and peripheral immune functions may be mediated by the zinc pool.

Effect of L-arginine on thymic function. Possible role of L-arginine: Nitric oxide (no) pathway.

The thymus and in particular its epithelial component produces hormonal peptides which are required for differentiation of stem cells into mature T-cells. With advancing age, there occurs a progressive reduction of the plasma level of one of the best known thymic peptides, i.e. thymulin. In old mice, oral supplementation with arginine (9x10(-4) gr/day/mouse) for 1 month is able to induce a regrowth of the thymus and recovery of the reduced thymulin plasma level to the values observed in young animals. The direct immunological target of arginine seems to be the thymus gland. In fact, the transplantation of thymus from old arginine treated mice into young thymectomized recipients is able to restore thymulin plasma level in thymectomized recipients to nearly the same level as do thymuses from young mice. Furthermore, arginine supplementation young thymectomized recipients is unable to induce the reappearance of thymulin activity in the blood. With regard to the mechanism of action of arginine, two pathways may be suggested. The first one may be indirect and mediated by the secretagogue action of arginine on growth hormone. The second one, may rely on a direct action through the L-arginine: NO pathway. Lymphocyte-depleted thymic explants from young mice, when incubated in vitro with the NO-synthetase inhibitor L-NAME (6 mM), are, in fact, incapable of producing and realising thymulin in the supernatant. The in vitro addition of L-arg (60 mM) is able to recover such a production to the values observed in supernatants of control thymic cultures. The present findings offer the first evidence that also the thymic endocrine activity is modulated by L-arginine:NO pathway.

Restoring effect of oral supplementation of zinc and arginine on thymic endocrine activity and peripheral immune functions in aged mice.

Previous work from this laboratory has demonstrated that both a trace element, zinc, and an amino acid, arginine, are capable, when orally administered, to recover some age-related immune dysfunctions. In the present paper the effectiveness of a zinc-arginine combination versus the single nutrients in restoring age-related immunological alterations in old Balb/c mice has been investigated. The zinc-arginine combination is more effective than the treatments of single nutrients alone. In particular on the reactivation of thymic endocrine activity, as measured by the circulating level of one of the best known thymic factors, i.e. thymulin (Zn-FTS) and the natural killer (NK) cell activity, particularly under boosting condition by interleukin-2 (IL-2) or interferon (IFN). On the other parameters tested the zinc-arginine combination either was not more effective than the single nutrients or a prevalence of one of them was detectable, such as of arginine on mitogen response or of zinc on basal NK activity. The findings clearly suggest that nutritional interventions and particularly combination of nutrients may represent an interesting and side-effect deprived approach for immunorestoration in elderly people.