Inhibition of gastric secretion and stress-induced ulcers by intravenous Asu(1,7)eel-calcitonin independent of vasopressin

The effects of different doses of Asu(1,7) eel-calcitonin, peripherally injected, on gastric secretion were studied in conscious Brattleboro rats, which are genetically deficient in vasopressin. Moreover, we evaluated the activity of this analogue on gastric ulcer formation by restraint stress. We found that 5 IU/kg Asu(1,7) eel-calcitonin decreased gastric secretion and inhibited the development of stress-induced ulcers in Brattleboro rats. These data suggest that vasopressin does not play a role in the gastrointestinal activity of Asu(1,7) eel-calcitonin.

Effects of salmon calcitonin on plasma renin activity and systolic blood pressure in the rat

Salmon calcitonin, centrally injected, increased plasma renin activity and blood pressure in rats. It is possible that the peptide through an action on the central serotonergic tone stimulated plasma renin activity with subsequent enhancement of blood pressure. Conversely, peripheral administration of the peptide increased plasma renin activity but did not cause changes in blood pressure. Probably, the enhancement of renin may be a physiological response to the renal activity of calcitonin; however, this activity does not seem to involve urinary prostaglandins.

Inhibition of restraint stress by systemic (Asu1,7) eel-calcitonin

The effects of different doses of (Asu1,7) eel-calcitonin, iv injected, on gastric secretion were studied in conscious rats with pyloric occlusion. Moreover, we evaluated the activity of this analogue on gastric ulcer formation by restraint stress. It was found that 2.5 or 5 Ul/kg (Asu1,7) eel-calcitonin decreased gastric acid secretion and inhibited the development of stress-induced ulcers in rats. In the isolated rat stomach the peptide at the concentrations of 1 nM to 1 microM did not modify acetylcholine, histamine or 5-hydroxytriptamine-induced contractions. These results suggest that this peripheral activity of (Asu1,7) eel-calcitonin does not involve a direct interference with cholinergic, histaminergic or serotonergic pathways at gastric level.

The analgesic activity of calcitonin and the central serotonergic system

The effect of peripherally administered cyproheptadine or reserpine and the administration of 5,7-dihydroxytryptamine (5,7-DHT) in the nucleus raphe dorsalis on the analgesic activity of salmon calcitonin (sCT) injected into the lateral ventricle were investigated in male rats. Cyproheptadine or reserpine, given respectively 30 min or 24 h before the peptide, completely abolished the analgesic activity at all the times studied. However, when reserpine was given before the peptide it increased the effect of sCT at 30 (P less than 0.01), 60 (P less than 0.001), 120 (P less than 0.01) and 180 (P less than 0.01) min. 5,7-DHT injected in the nucleus raphe dorsalis 15 days before the peptide led to complete abolition of the analgesic activity. If neurotoxin was injected 4 days before sCT, the effect of the peptide was significant (P less than 0.05) only at 60 min. The results obtained confirm that the analgesic activity of sCT may involve central serotonergic pathway(s), and that the midbrain raphe nuclei 5-HT content is an important focus for this activity.

Effect of calcitonin on ACTH secretion

We have investigated the effects of salmon calcitonin injected intracerebroventricularly on adrenocorticotropic (ACTH) secretion in rats. Salmon calcitonin was able to increase significantly (p less than 0.05) ACTH secretion at the dose of 5 ng/rat and (p less than 0.01) at the doses of 12.5, 25 and 50 ng/rat; the effect (50 ng/rat) was maximal at 30 min and still present after 60 and 120 min. The maximal dose of calcitonin produced a significant (p less than 0.05) increase in serum ACTH concentration also in stressed animals. It is suggested that calcitonin may increase serum ACTH secretion by central norepinephrine and/or 5-hydroxytryptamine pathways that regulate corticotropic releasing factor activity.

Effects of dopaminergic drugs on cerebellar prostaglandin concentrations

Previous data indicate that the injection of dopaminergic drugs induces changes in cerebellar 3',5'-guanosine monophosphate (cGMP) content. Accordingly, we have investigated the effects of haloperidol, sulpiride, or apomorphine on cerebellar prostaglandin (PG) concentration, a parameter related to cGMP content. Results obtained show that dopamine receptor blocking agents, such as haloperidol and sulpiride, significantly decrease cerebellar PGE2 and PGF2 alpha concentrations, while opposite changes are induced by apomorphine, a dopamine receptor agonist.

[Effects of dopaminergic drugs on the concentrations of PGE2 and PGF2alpha in various brain regions]

It has long been shown by Biggio and Guidotti that multisynaptic nigro-cerebellar pathway of dopaminergic origin can control cerebellar cyclic guanosinmonophosphate (cGMP) content, a good index of the activity of Purkinje cells. In this line, it has been reported that haloperidol and sulpiride, significantly decrease cerebellar cGMP content while opposite changes are observed with apomorphine. In an attempt to establish whether other cerebellar cGMP-related parameters may be influenced by dopamine drugs. Authors have investigated the effects of haloperidol, sulpiride and apomorphine on cerebellar PGE2 and PGF2alpha. Results obtained indicate that haloperidol and sulpiride significantly reduce cerebellar PGE2 and PGF2alpha content while opposite changes are induced by apomorphine. Similar results have been observed in substantia nigra but not in other brain regions, such as corpus striatum and medial basal hypothalamus. The possibility that the observed changes in cerebellar PG-content may result from the modulation of striatal dopamine receptors is discussed.

[Vitamin E and experimental caries in rats fed a cariogenic diet and zinc]

A cariogenic diet with zinc and vitamin E administered to rats for 90 days led to a reduction in caries of 21.87% by comparison with animals fed with the cariogenic diet only, and 3.12% by comparison with those that received the diet plus zinc. Although the details of the mechanism of action of vitamin E are not fully known, it is felt that its demonstrated cariostatic effect depends on its antioxidant activity and its protection of the sulphydryl groups of some enzyme system, together with its direct intervention in cell respiration. Since both vitamin E and zinc activate NAD-dependent LDH, their simultaneous administration enhances their individual cariostatic effects by bringing about a lower accumulation of lactic acid in the bacterial plaque.

[Effects of zinc and vitamin B 6 in experimental caries in rats]

The behaviour of caries has been studied in rats kept on a cariogenic diet enriched with zinc and vit. B6. A reduction of 16.7% in caries was observed compared to control animals fed with the cariogenic diet alone. Compared to the controls, the animals treated with Ershoff diet and zinc presented a decrease of 18.76%. The weight increase curves of the three lots of rats appeared similar. The basic role played by pyridoxal phosphate in all metabolism is recalled and the cariostatic action exerted by vit. B6 on the optimal function of two pyridoxal-phosphate-dependent systems transaminase and enzymes engaged on the synthesis of acetyl-CoA, reported. Both reduce the acid complement deriving from bacterial plaque fermentation, transaminase by deviating pyruvic acid from glycolysis to protein metabolism, acetyl-CoA synthesis by triggering Krebs cycle oxidative decarboxylation.

Investigations on behavioral effects of an extract of Cannabis sativa L. in the rat

The behavioral responses of the rat to an extract of Cannabis sativa were examined after IP injection of 5, 15 and 30 mg/kg (expressed as delta 9 tetrahydrocannabinol). The lowest dose of the extract induced stereotyped behavior (rhythmic head movements, intermittent gnawing and sniffing) together with hypersensitivity to stimuli and hyperthermia. The administration of higher doses of the extract resulted, initially, in similar behavioral effects but of greater intensity, followed by a cataleptic state alternating with atonic muscular prostration; rectal temperature was decreased. Pre-treatment with 6-hydoxydopamine (6-OHDA, which produces degeneration of catecholamine-containing nerve terminals)or pimozide (blocker of dopamine receptors) significantly reduced both stereotype and hyperreactivity. Thermic effects were also antagonized by 6-OHDA pre-treatment. Cannabis-induced catalepsy was enhanced by pimozide but reduced by atropine (3 mg/kg SC). These results support the hypothesis that catecholamines play an important role in the complex behavioral effects of cannabis.

[Incidence of dental caries and malocclusion in the elementary schools of Aci Castello (Catania)]

Using the OMS form, the Authors relate the percentage of dental decay (78.34%) and of dentofacial anomalies (36.41%) in 651 children from the age of 6 to 10, reporting a light prevalence of caries in female children (79.03% versus 77.64%) and of anomalous occlusions in male children (37.26% versus 35.55%). Besides, the Authors analyze the D.M.F. values of each dental segment and compare the various types of anomalous occlusions. Noting that the percentage in anomalous occlusions increases as the age of children goes up, the Authors remark that the anomalous occlusions of the first class of Angle are more frequent in children with bad dental status (67.81% versus 63.03%).

[Clinical statistical evaluation of the antiplaque efficacy of therapeutic aids]

The results of a blind comparison of different types of toothpaste carried out for two months are reported. It was noted that the paste based on azulene, sodium chloride and benzalkonium chloride produces a more marked regression in the gingival index, whereas that based on chlorhexidine produces a more marked reduction in the plaque index. The differences were not statistically significant, however. With an equal quantity of tooth-paste, it was shown that two initial sessions of ultrasonic detartrasis produce a statistically significant benefit as regards gingival index regression, but an only apparent one for the plaque index. Detartrasis alone, not followed by regular oral hygiene practice, leads to momentary benefits but, as the weeks go by, the difference between the indices of those submitted to detartrasis alone and those who also adopt recommended toothpastes regularly becomes increasingly significant.