Efficacy of ginger-based treatments against infection with Gyrodactylus turnbulli in the guppy (Poecilia reticulata (Peters)).

Monogenean infections of commercially farmed fishes are responsible for significant economic losses and existing chemical therapeutants, often stressful to the fish, pose associated risks. As part of a recent trend to move towards the use of alternative, plant-based remedies for commonly occurring aquaculture-related diseases, the efficiency of ginger (Zingiber officinale) was investigated against the monogenean parasite Gyrodactylus turnbulli in the guppy. In vitro trials revealed the clear anti-parasitic effects of ginger. Ethanolic and aqueous extracts, prepared from freeze dried ginger, were tested. An increase in extract concentration was associated with reduced time to parasite immobilisation, with ethanolic extract being more efficient; at 75 and 200ppt aqueous ginger extract parasites died at 65.6±2.8 and 1.8±0.2min, respectively, whereas at 5 and 40ppt ethanolic extract parasites died at 26.1±0.7 and 4.9±0.3min, respectively. Bathing G. turnbulli-infected fish in ethanolic ginger extract (i.e. 5 and 7.5ppt for 90 and 30min, respectively) significantly reduced infection prevalence and intensity when compared to the water and ethanol controls. The higher concentration (i.e. 7.5ppt) proved as equally effective as Praziquantel, the conventionally used chemical treatment for gyrodactylosis, with the fish appearing to be completely cleared of the infection in both cases. Oral treatments of G. turnbulli-infected guppies with diets supplemented with 10 and 20% ginger powder proved to be ineffective in decreasing parasite load. These findings demonstrate that immersion in ginger extract offers an effective, alternative treatment against monogenean infection in fish.

[Excessive prolactinemic response to sulpiride in patients with mild essential hypertension. Index of diminished hypothalamic dopaminergic activity]. / Eccessiva risposta prolattinemica alla sulpiride in pazienti con ipertensione essenziale lieve. Indice di diminuita attività dopaminergica ipotalamica.

Plasma prolactin concentrations and prolactinaemic response to sulpiride, a prolactin releaser with pituitary dopamine receptor blocking activity, were examined in 16 subjects with mild essential hypertension and in 20 patients with long-sustained essential hypertension. When compared with 16 normotensive controls only the former showed raised plasma renin activity (P < 0.001) and higher plasma prolactin levels either after two-hour ambulation (P < 0.05) or at supine rest (P < 0.05). The average of maximal sulpiride-induced prolactin values was 157 +/- 53 ng/ml (mean +/- SD) in the mild hypertensive, significantly different from 60.2 +/- 21.4 ng/ml (mean +/- SD) as resulted in the controls (P < 0.001). In contrast, patients with sustained hypertension had a mean level of 60.2 +/- 21.4 ng/ml (mean +/- SD), indifferent from the one of the normal volunteers. It is suggested that the excessive prolactinaemic response to sulpiride detected in patients with mild hypertension reflects a reduced hypothalamic dopaminergic activity and that such an alteration may assume some pathogenetic relevance in the natural history of essential hypertension. Further, in the mild hypertensive a positive prolactin-renin correlation was found (r = + 0.76; P < 0.01), so suggesting that in these patients a peripheral sympathetic overactivity is associated to an impaired central dopamine control. The individuation of such cases may be important since they could benefit by dopamine agonists as L-dopa and bromocriptine.