The effect of GnRH on in vitro bovine myometrial activity.

The aim of this study was to evaluate, in vitro, the effects of increasing concentrations of GnRH on spontaneous mechanical activity patterns of uterine smooth muscle preparations of cows during the follicular and the luteal phases of the oestrus cycle. Uterine smooth muscle strips from 14 cows in follicular and 9 in luteal phase were collected immediately after slaughter and processed within 60 min from collection. Two strips of the same uterus were mounted in an isolated organ bath with two chambers to evaluate the role of decapeptide GnRH on spontaneous myometrial contractility. After equilibration period at 20 mN resting tension, the mechanical activity of the uterus was recorded for 10 min and the mean contractile force (MCF) was calculated. Then GnRH antagonist (antide) was added to one chamber at fixed concentration (10(-4)mol) and allowed to diffuse in solution and make contact with the strips. Subsequently, GnRH was added to the two baths at the same time at increasing concentration and MCF was recorded for 10 min. The effect of GnRH on spontaneous myometrial activity was evident only in the strips from subjects in follicular phase. Our results are suggestive of the presence of GnRH receptors in bovine myometrial tissue. The involvement of GnRH on uterine contractions at mating can be postulated.

Use of a synthetic GnRH analog to induce reproductive activity in canaries (Serinus canaria).

In this study, we evaluated the effects of a transcutaneously administered gonadotropin-releasing hormone analog (lecirelin) on the reproductive activity of the canary (Serinus canaria). Two groups of 20 pairs of canaries were treated with increasing concentrations of lecirelin delivered in a cream vehicle; one group was exposed to a natural photoperiod, and the other group received additional photostimulation. Two groups of 10 pairs of canaries served as controls; one group was exposed to an artificially lengthened photoperiod, and the other group was maintained under a natural photoperiod and treated with a nonmedicated cream vehicle. In all canaries treated with lecirelin, the onset of reproductive activity occurred significantly earlier than in either control group.

Comparing therapeutic efficacy between ivermectin, selamectin, and moxidectin in canaries during natural infection with Dermanyssus gallinae.

The aim of this study was to compare the efficacy of three spot-on drugs on canaries during Dermanyssus gallinae natural infections and during the breeding season. Three groups of canary couples (seven couples each) were included: group A was treated with ivermectin, B with selamectin, and C with moxidectin. All the drugs were administered topically infrascapularly. The parasitic charge was estimated before the treatment (t(0)) and after 8 (t(1)), 16 (t(2)), 24 (t(3)), and 32 (t(4)) days following the initial treatment. No significant differences were detected among the three tested drugs for the five repeats for each of the four mite stages (egg, larva, nymphs, and fed and unfed adults). With regard to the decrease in the mean numbers of red mites, ivermectin and selamectin exerted their efficacy at t(2), contrary to moxidectin at t(3).

In vitro evaluation of gut contractile response to histamine in rainbow trout (Oncorhynchus mykiss Walbaum, 1792).

The contractile response of intestinal strips in rainbow trout (Oncorhynchus mykiss Walbaum, 1792) to the administration of histamine was assessed by means of the organ bath technique. Intestinal strips were isolated from 16 clinically healthy fish and mounted in organ baths. Histamine was compared with the full agonist serotonin, to evaluate their contractile efficacy and potency. Serotonin elicited a concentration-related contraction in all examined intestinal strips, whereas histamine induced the contraction only in 14 exemplars. Of these, seven exhibited a concentration-related response. A sigmoidal curve was fitted from data (R(2) = 0.55) and its best fit values were compared with those of serotonin. Interestingly, histamine exhibited the same efficacy (E(max)) as serotonin (F-test, p > 0.05), but showed lower potency (by an order of magnitude) (F-test, p < 0.01). Moreover, the effect of the H1 antagonist, pyrilamine, has been tested to exclude aspecific contraction due to other agonists eventually released in situ following histamine administration. Pyrilamine showed a marked concentration-related antagonist action on the contractility induced by histamine with complete contractility antagonism at 10(-4)M. The authors suggest that the responses to histamine measured in the present study reflect a less sensitive response to an exogenous source of histamine, possibly due to bacterial metabolism.

Faecal concentration of cortisol metabolites in prepartum ewes.

This study was performed to determine the endocrinological starting point of parturition in ewes and to study correlations between the viability of offspring and the concentrations of faecal cortisol metabolites in the dam using 11-oxoetiocholanolone EIA (measuring 11,17-dioxoandrostanes). The levels of faecal cortisol metabolites of 10 ewes positive for ovine pulmonary adenocarcinoma (OPA) were compared against 10 negative ewes during the last week of gestation and 12 h after delivery. The mean concentration in the OPA group was higher (500-600 ng/g) than that observed in the control group (150-200 ng/g). The mean cortisol level showed a significant (p<0.05) increase during the last two days of pregnancy in all subjects (OPA and controls). The increase in faecal cortisol metabolites was not significant (p>0.05) in three animals (2 OPA and 1 control); their offspring showed low viability and died soon after delivery. These results underline that the mean baseline faecal cortisol metabolite concentration in ewes does not affect physiological pregnancy while, to ensure viability of lambs, it is essential that the cortisol level increases significantly (90%), regardless of its baseline level.

Assessment of edible marine species in the Adriatic Sea for contamination from polychlorinated biphenyls and organochlorine insecticides.

It is estimated that 90% of human exposure to persistent organic pollutants is through food, and fish and shellfish represent an important source of contamination for polychlorinated biphenyls (PCBs) and organochlorine insecticides. To evaluate the levels of seafood contamination coming from the central Adriatic Sea, Italy, a study involving several pools of shellfish, crustaceans, and fish was carried out. Several marine species were selected by their abundance, wide distribution, and common use in the Italian diet and sampled and analyzed during 2004. The concentration of total (sigma) PCBs exceeded that of total dichlorodiphenyltrichloroethanes (DDTs) in all samples. Atlantic mackerel showed the highest concentrations of PCBs, ranging from 514 to 1772 ng/g of fat weight, and DDTs, ranging from 52 to 656 ng/g of fat weight. The lowest concentrations of PCBs and DDTs were found in cephalopods and mussels. Despite this, to protect human health from these pollutants, legal limits have been established for fish and shellfish for DDTs but not PCBs. The most common representative PCB congeners, in all species, were PCB 153 and PCB 138; the most common DDT was p,p'-dichlorodiphenyldichloroethylene.