Could zinc prevent reproductive alterations caused by cigarette smoke in male rats?

The aim of the present study was to evaluate the effects of zinc on fertility through semen parameters, testosterone level and oxidative DNA damage to spermatozoa of rats exposed to cigarette smoke. Male Wistar rats (60 days old) were divided into four groups (n = 10 per group): control, cigarette-smoking (20 cigarettes per day), zinc (zinc chloride 20 mg kg⁻¹ day⁻¹) and zinc plus cigarette-smoking (zinc chloride 20 mg kg⁻¹ day⁻¹; 20 cigarettes per day). The treatment was applied for nine weeks and the following parameters were analysed: bodyweight, wet weights of the reproductive organs and the adrenal gland, plasma testosterone concentration, testicular function (seminal analysis and daily sperm production) and sperm DNA oxidative damage. The exposure to cigarette smoke decreased testosterone concentration, the percentage of normal morphology and the motility of spermatozoa. In addition, this exposure increased sperm DNA oxidative damage. Zinc treatment protected against the toxic damage that smoking caused to spermatozoa. This study showed a correlation between smoking and possible male infertility and subfertility, and also that the majority of smoking-induced changes in spermatozoa were prevented by zinc treatment. In conclusion, zinc, an antioxidant and stimulant of cell division, can be indicated as a promising treatment in men with infertility caused by the toxic components of cigarette smoke.

Effects of cigarette smoke exposure on pregnancy outcome and offspring of diabetic rats.

A total of 52 female Wistar rats were distributed into four groups: non-diabetic (G1) and diabetic (G2) exposed to filtered air; non-diabetic (G3) and diabetic (G4) exposed to cigarette smoke. Diabetes was induced by streptozotocin (40 mg/kg bodyweight, i.v.). Rats were exposed, for 30 min, to filtered air (control) or to tobacco smoke generated from 10 cigarettes, twice a day, for 2 months. At the end of the 2-month exposure, at day 21 of pregnancy, each rat was anesthetized and humanely killed for laparotomy. Uterine horns were exposed for reproductive performance analysis, fetal and placental weights and placental index. Maternal and fetal data were analysed by ANOVA followed by the Student Newman-Keuls test. Fetal weight classification was assessed by Fisher's exact test. Diabetes and cigarette smoke caused placentomegaly (G4 = 0.65 +/- 0.19 g versus G1 = 0.49 +/- 0.03 g, P < 0.05), increased placental index (G4 = 0.13 +/- 0.03 versus G1 = 0.09 +/- 0.00, P < 0.05) and small fetus rates for pregnancy age (G4 = 88% versus G1 = 23.2%, P < 0.05). These observations show the importance of encouraging pregnant women to attempt cessation of smoking.

Could neonatal testosterone replacement prevent alterations induced by prenatal stress in male rats?

The present study was designed to examine whether testosterone replacement is able to prevent some effects of maternal restraint stress--during the period of brain sexual differentiation--on endocrine system and sexual behavior in male rat descendants. Pregnant rats were exposed to restraint stress for 1 h/day from gestational days 18 to 22. At birth, some male pups from these stressed rats received testosterone propionate. The neonatal testosterone replacement was able to prevent the reduction in anogenital distance at 22 days of age observed in pups from stressed pregnant rats as well as prevents the decrease in testosterone levels during the adulthood of these animals. Testosterone replacement in these males also presented an improvement in sexual performance. In this way, testosterone replacement probably through increasing neonatal level of this hormone was able to prevent the later alterations caused by the prenatal stress during the period of brain sexual differentiation.

Adrenergic response patterns in vas deferens isolated from rats under diurnal rhythms. Influence of stress.

The aim of this study was to verify, by means of functional methods, whether the circadian rhythm changes adrenergic response patterns in the epididymal half of the vas deferens isolated from control rats as well as from rats submitted to acute stress. The experiments were performed at 9:00 a.m., 3:00 p.m., 9:00 p.m., and 3:00 a.m. The results showed a light-dark dependent variation of the adrenergic response pattern on organs isolated from control as well as from stressed rats. In the control group, only the phenylephrine sensitivity was changed throughout the circadian rhythm. Under the stress condition, both norepinephrine and phenylephrine response patterns were changed, mainly during darkness. The maximal contractile response to both alpha- and beta-agonist and alpha1-agonist was increased in the dark phase, corresponding to high plasmatic concentrations of endogenous melatonin. The vas deferens isolated from stressed rats during the light phase simultaneously incubated with exogenous melatonin showed the same pattern of response obtained in the dark phase, thus indicating a peripheric action of melatonin on this organ. Therefore, the circadian rhythms are important to the adrenergic response pattern in rat vas deferens from both control and stressed rats. In conclusion, we suggest a melatonin modulation on alpha1-postsynaptic adrenergic response in the rat vas deferens.

Puberty installation and adrenergic response of seminal vesicle from rats exposed prenatally to hydrocortisone.

We investigated the effects of hydrocortisone during the prenatal period and its repercussion on puberty installation and adrenergic response of seminal vesicle in adult rats. The efficacy of the hydrocortisone treatment in reducing adrenal wet weight immediately after delivery in both the treated mothers and respective pups at birth may indicate impairment of the hypothalamus--pituitary--adrenal axis. This parameter was unchanged in the adult phase of these descendants, suggesting recuperation of this axis. In addition, the treatment with hydrocortisone delayed the age of puberty installation, probably by absence of both physiologic production and liberation of luteinizing hormone and testosterone. Despite the significant reduction in testosterone level as well as of wet weights of both vas deferens and testis in the adult phase, no difference was observed in the sensitivity of the seminal vesicle to the studied sympathetic agonist. However, the observed reduction in contractile response of the seminal vesicle may be a consequence of contractile-system damage in this organ. It is possible that this alteration may cause a reduction in the amount of vesicular secretion so important in the process of ejaculation. In conclusion, these results suggest that administration of hydrocortisone in late prenatal life did not influence the hypothalamus--pituitary--adrenal axis in adult life, although it altered the hypothalamus--pituitary--gonadal axis, and reduced testosterone production starting at puberty, as a consequence of an incomplete masculinization of the hypothalamus plus a reduction in the contractile response of the seminal vesicle.

5alpha-reductase 2 inhibition impairs brain defeminization of male rats: reproductive aspects.

The present study was carried out to determine whether 5alpha-reductase 2 (5alpha-R2) metabolic pathway plays a key role in brain sexual differentiation. The inhibition of 5alpha-R2 by finasteride (20 mg/kg/day) from gestational day 19 to postnatal day 5 has long-term effects on sexual behavior and reproductive physiology detected only in adult life. Sexual maturation assessed by timing of preputial separation was unchanged. Finasteride-treated males were able to mate with untreated females which became pregnant but exhibited increased rate of pre-implantation loss. The subfertility observed was probably due to abnormally shaped sperm, since the sperm number was not altered. While plasma testosterone was enhanced, LH levels were not changed. The copulatory potential was not affected and all finasteride-treated rats presented male sexual behavior. Despite this, 53% of them showed homosexual behavior when pretreated with estradiol, suggesting an incomplete brain defeminization. These results indicate that 5alpha-R2 acts in brain sexual differentiation of male rats. Moreover, we suggest that 5alpha-R2 not only produces essential metabolites that act together with estradiol in brain sexual differentiation but also protects the brain from the damaging effects of estradiol excess.

Norepinephrine responses in rat renal and femoral veins are reinforced by vasoconstrictor prostanoids.

Norepinephrine (NE) responses are larger in renal and femoral veins compared to phenylephrine (PE). These differences may be due to the subtypes of adrenoceptor involved in these responses or to the involvement of local modulatory mechanisms. Therefore, the present study investigated in organ bath the adrenoceptor subtypes involved in the NE and PE responses in both renal and femoral veins as well as the influence of local mechanisms related to NO and to prostanoids upon these responses. The obtained data showed that the NE responses in these veins were not significantly modified by the selective inhibition of ß1 or ß2-adrenoceptors as well as AT1 or AT2 receptors. However, yohimbine reduced the NE Rmax in renal veins and, in parallel, right shifted the NE concentration-response curves in femoral veins. In both veins, prazosin reduced the NE Rmax and the clonidine induced a measurable contraction. The endothelium removal attenuated the NE responses in femoral veins, thereby abolishing the differences of NE and PE responses. Furthermore, the NE responses in renal and femoral veins were attenuated by indomethacin, which suppressed the statistical difference in relation to the PE response. In conclusion, a synergism between α1- and α2-adrenoceptors is essential to assure full NE contractile responses in both renal and femoral veins. Thus, by acting simultaneously in these adrenoceptors, NE induces more pronounced contractile responses, in comparison to PE, not only in renal but also in femoral veins. Moreover, this pronounced NE response in both renal and femoral veins appears to involve endothelium-derived vasoconstrictor prostanoids.

Semen and reproductive parameters during some abstinence periods after cigarette smoke exposure in male rats

Cigarette smoking is very widespread globally and can also be implicated in male and female infertility. This study aimed to evaluate the testicular function throughout a complete spermatic cycle during abstinence from cigarette smoke exposure in order to identify a possible residual damage and whether the parameters could recover spontaneously. Male Wistar rats were randomly divided into control and cigarette smoke-exposed (20 cigarettes/day/2 months) groups. After finishing the treatment, according to the number of days after the last cigarette exposure (0, 15, 30, or 60 days), the rats were euthanized and analyzed for compromised sperm count and quality. Results showed residual damage on sperm concentration, motility and morphology; the recovery of these parameters occurred only at 60th days of abstinence. The study showed that cigarette smoke exposure damaged the semen and reproductive parameters and that the spontaneous recovery of some parameters occurred only after a complete spermatic cycle subsequent to stopping smoke exposure.

A sobrevida de ratos com tumor de Walker submetidos previamente à imunogenicidade das células tumorais / Survival in rats with Walker's tumor submitted previously to the tumoral cells immunogenicity

A inoculaçao de 37.10 5 células do tumor de Walker, por via intramuscular, na coxa do rato confirmou uma evoluçao rápida do mesmo, ao exibir um crescimento expansivo da massa tumoral no local do inóculo, culminando com a morte do animal. Todavia, quando da inoculaçao em ratos expostos previamente à "imunogenicidade destas células", observou-se uma evoluçao mais lenta e uma maior sobrevida, sugerindo modulaçao na imunidade destes animais. O contato prévio com as células tumorais ou ainda a fraca imunogenicidae destas células, provavelmente, possa ter sido suficiente e responsável pelo retardo no desenvolvimento do tumor e pela maior sobrevida dos animais

Determinação de catecolaminas em amostras de plasma de ratos por injeção direta usando CLAE / Determination of catecholamines in plasma from rats by direct injection using HPLC

No presente trabalho, foram feitos ensaios para a determinação de catecolaminas(noradrenalina, adrenalina e dopamina) em plasma de rato. As análises quantitativas foram feitas por cromatografia líquida de alta eficiência com detecção UV. o método envolveu injeção direta da amostra de plasma em uma coluna cromatográfica com superfície interna de fase reversa (HSA_C18) e a fase móvel foi composta por solução de fosfato diácido de sódio 0,05mol.L-1 (ph=6,0) e acetronitrila (97,5:2,5 v/v), contendo 0,01g de ácido heptanussulfônico. A identificação do analitos foi baseada nos tempos de retenção de cada catecolamina e a quantificação foi feita pela determinação da áres do pico do analito

Importância do Controle dos níveis de catecolaminas em experimentação científica / Importance of the control of catecholamines levels in the scientific experiment

A sídrome de estresse é caracterizada por complexas alterações neuroendocrinológicas. Essas alterações, ao menos parcialmente, fazem parte de um mecanismo de ajuste de tecidos. Assim, foram avaliados os níveis plasmáticos de catecolaminas(noradrenalina, adrenalina, dopamina e Lodopa) em ratos. Os resultados mostram o aumento dos níveis plasmáticos de adrenalina resultante da reação de alerta causada pela manipulação dos animais. desta forma, é possível a obtenção de respostas alteradas em função do estresse de manipulação. Todavia, para que se possam analisar respostas fisiofarmacológicas e considerá-las como alteradas é necessário que se estabeleça uma padronização experimental rígida bem como uma resposta "controle" altamente confiável

Role of androgenic deprivation on the contractile response to norepinephrine in vas deferens isolated from rats submitted to swimming-stress

O presente estudo objetivou o efeito da castraçäo na resposta contrátil à noradrenalina em ducto deferente de ratos previamente submetidos ao estresse agudo, induzido pela nataçäo forçada. O estresse agudo levou à subsensibilidade à noradrenalina em ductos deferentes provenientes de ratos intactos. Semelhantemente, a castraçäo também induziu subsensibilidade à noradrenalina, mas näo ocorreu subsensibilidade adicional em ductos deferentes isolados de ratos castrados submetidos ao estresse agudo. Os resultados mostraram também resposta diferente à noradrenalina, em termos de responsividade relativa (p), quando os ductos deferentes foram retirados de ratos castrados ou castrados submetidos ao estresse agudo. Sugere-se que os esteróides androgênicos exercem um papel importante na regulaçäo da resposta do ducto deferente à noradrenalina durante a situaçäo de estresse agudo. Este efeito parece envolver mecanismos que atuam na sensibilidade dos receptores adrenérgicos e no sistema de captura neuronal de catecolaminas.

Determinaçäo de cafeína em amostras de urina por injeçäo direta no HPLC / Determination of caffeine in urine samples by direct injection in to HPLC

Desenvolveu-se um método analítico para a extração e determinação das concentrações de cafeína em amostras de urina por cromatografia líquida de alta performance. O método envolve a injeção direta da amostra de urina em uma coluna cromatográfica ISRP (150mm X 4,6mm DI) empregando uma fase móvel composta por uma solução de fosfato dibásico de sódio 0,05 umol. L -1 (pH 8,0) e acetonitrila (90:10 v/v). As recuperações de cafeína presentes em amostras de urina fortificadas forma maiores que 98,40 mais ou menos 0,90 por cento com um desvio padrão relativo de 0,48 por cento. O limite de detecção para a determinação de cafeína foi de 0,1 mg.u L-1. O range de linearidade do detector foi determinado entre a s concentrações 0,1 a 18,0 ug.mL-1 para a cafeína.

Determinaçäo por injeçäo direta no HPLC de cocaína em amostras de urina e em amostras de papelotes de cocaína e crack / Determination by direct injection into HPLC of cocaine, in urine samples, cocaine and crack unit samples

Desenvolveu-se um método analítico para a extraçäo e determinaçäo de cocaína em amostras de urina. O método permite a injeçäo direta da amostra de urina em uma coluna cromatográfica ISRP-C8 (100mm x 4,6mm DI), empregando uma fase móvel composta por uma soluçäo de fosfato dibásico de sódio 0,05mol.L (pH 8,0) e acetonitrila 70:30 (v/v)