ABSTRACT. To study the effect of estrogenic chemicals on fish, the gonadosomatic index (GSI = [testis weight/body weight] × 100) and testis histology of mature common carp (Cyprinus carpio) from 2 contaminated sites (Ishizu and Wada rivers, Osaka) and a control site were examined between June 1998 and March 2001. The concentration of nonylphenol, bisphenol A and 17β-estradiol in the Ishizu river was 3-4 times higher than in the Wada river. In the pre-breeding and breeding seasons, there were no significant differences in body weight among carp from the 3 sites, the body weight of Ishizu river carp being significantly lower (p<0.05) than that of Wada river fish only in the post-breeding season. The GSI and testis weight in fish from the Ishizu river were significantly lower (p<0.05) than in control fish during all phases of gonadal cycle and lower than in Wada river fish in the pre-breeding and post-breeding season. No histological abnormalities were found in the testes of the males examined. Histological observation of the testes revealed a delay in the onset of spermatogenesis in fish from the Ishizu river compared with those from the other sites. These results clearly imply that the estrogenic chemicals in the Ishizu river adversely affect the testis development of the fish. There is growing evidence in support of the claim that contamination of a wildlife population with estrogenic chemicals can disturb the reproductive function of vertebrates [6,7,12]. Many researches have been focused on fish, since as aquatic inhabitants they receive sewage or industrial effluent and agricultural runoff containing estrogenic chemicals [5,14,30]. In fish, estrogenic responses have been associated with exposure to pesticides [3,35], pulp mill effluents [23,29,34], plasticizers [19] and sewage effluent [2,17,31]. Abnormalities have also been reported in the male reproductive system of fish living in water polluted by sewage or industrial chemicals [12,25]. Studies on the male teleost revealed changes including induced vitellogenin production [5,13,14,20], hermaphroditism as evidenced by the presence of both testicular and ovarian tissues [8,10,11,18,31], reduced testis size [20] and reduced plasma androgen concentrations together with delayed sexual maturity [26].Some information is known on the effect of estrogens and estrogenic chemicals on the carp testis, and their relation to seasonal changes in testis morphology. Three-month exposure to a sublethal dose of 4-tert-pentylphenol or 17β-estradiol causes progressive disappearance of spermatozoa and spermatogenic cysts, and reduces the seminiferous tubule diameter, in mature male carp [11]. Ovo-testes were found in juvenile carp exposed to xeno-estrogens during sexual differentiation [8,9]. However, a field study on adult crucian carp (Carassius carassius) living in a pond containing treated pulp mill effluent showed no gonadal deformation or feminization of male gonads [23]. It is therefore important to study the testis of mature male carp (Cyprinus carpio) living in rivers ...

ABSTRACT. Renal effects of the selective α 2 -adrenoceptor agonist, medetomidine, were investigated in anesthetized dogs. Animals were administered medetomidine 20 and 40 µg/kg intravenously (IV) and 80 µg/kg intramuscularly (IM) or 1 ml of saline IV. Urine and blood samples were collected before and at 30, 60, 90 and 120 min following medetomidine injection. Mean arterial blood pressure (MABP), renal blood flow (RBF), glomerular filtration rate (GFR), urine volume (U v ), urine osmolality (U osm ), free water clearance (C H2O ), fractional clearance of sodium (F Na ), plasma osmolality (P osm ), plasma glucose levels and plasma antidiuretic hormone (ADH) concentrations were measured. The results showed that IV administration of medetomidine initially increased MABP 5-15 min followed by long-lasting decrease. The initial hypertension was not observed after IM administration, which was accompanied by a more profound hypotensive effects. RBF, GFR, U v , C H2O increased after IV injection and decreased after IM. Medetomidine increased FNa and Posm and decreased U osm . Plasma glucose levels initially increased and subsequently decreased. Plasma ADH concentration was decreased by IV injection but increased by IM administration. Our data imply that: 1) IV administration of medetomidine at dose rates of 20 and 40 µg/kg results in profound diuresis up to 2 hr; 2) Suppression of ADH release from the CNS is one of the mechanisms of medetomidine-induced diuresis although it may not be the principal one. KEY WORDS: anesthesia, canine, isoflurane, medetomidine and renal function.

No abstract

SUMMARY: Several functional and morphological studies have been conducted on the pineal gland in many mammalian species; however, no published reports are available on the role of pineal gland on the gonadal development before and after eyelids separation in puppies. Therefore, this study aimed to trace the postnatal histo-morphological changes in the pineal gland and gonads of puppies before (2, 10 and 11 days old) and after (25, 35 and 40 days old) eyelids separation in an attempt to investigate the possible role of pineal gland on the gonadal development. In general, the differentiation of pineal cells, interstitial endocrine cells of testes and stromal ovarian cells coincides with the start of eyelids separation in puppies. Histological examination of stained pineal and gonadal slices of puppies after eyelids separation revealed a remarkable differentiation of pinealocytes and testicular interstitial endocrine cells, as well as presence of some evidence of folliculogenesis in ovary. Surprisingly, melatonin receptor (MT1) protein expression levels were significantly increased in the ovaries and testes of puppies after eyelids separation. Moreover, the mRNA and protein expression of AANAT, a ratelimiting enzyme in melatonin biosynthesis, was notably increased in the pineal gland of opened eyes puppies. Our results suggest an increase of melatonin production from the pineal gland of opened eyes puppies and this could play a vital role in the developmental changes observed in the gonads of these puppies.

No abstract