Effect of Lactation on myocardial vulnerability to ischemic insult in rats / Efeito da Lactação sobre a Vulnerabilidade do Miocárdio ao Insulto Isquêmico em Ratas

Abstract Background: Cardiovascular diseases are the leading cause of mortality and long-term disability worldwide. Various studies have suggested a protective effect of lactation in reducing the risk of cardiovascular diseases. Objective: This study was designed to assess the effects of pregnancy and lactation on the vulnerability of the myocardium to an ischemic insult. Methods: Eighteen female rats were randomly divided into three groups: ischemia-reperfusion (IR), in which the hearts of virgin rats underwent IR (n = 6); lactating, in which the rats nursed their pups for 3 weeks and the maternal hearts were then submitted to IR (n = 6); and non-lactating, in which the pups were separated after birth and the maternal hearts were submitted to IR (n = 6). Outcome measures included heart rate (HR), left ventricular developed pressure (LVDP), rate pressure product (RPP), ratio of the infarct size to the area at risk (IS/AAR %), and ventricular arrhythmias - premature ventricular contraction (PVC) and ventricular tachycardia (VT). Results: The IS/AAR was markedly decreased in the lactating group when compared with the non-lactating group (13.2 ± 2.5 versus 39.7 ± 3.5, p < 0.001) and the IR group (13.2 ± 2.5 versus 34.0 ± 4.7, p < 0.05). The evaluation of IR-induced ventricular arrhythmias indicated that the number of compound PVCs during ischemia, and the number and duration of VTs during ischemia and in the first 5 minutes of reperfusion in the non-lactating group were significantly (p < 0.05) higher than those in the lactating and IR groups. Conclusion: Lactation induced early-onset cardioprotective effects, while rats that were not allowed to nurse their pups were more susceptible to myocardial IR injury.

Resumo Fundamento: As doenças cardiovasculares são a principal causa de mortalidade e invalidez a longo prazo a nível mundial. Diversos estudos têm sugerido um efeito protetor da lactação na redução do risco para doenças cardiovasculares. Objetivo: Este estudo foi desenvolvido para avaliar os efeitos da gestação e da lactação sobre a vulnerabilidade do miocárdio ao insulto isquêmico. Métodos: Dezoito ratas foram divididas aleatoriamente em três grupos: isquemia-reperfusão (IR), no qual os corações de ratas virgens foram submetidos à IR (n = 6); lactantes, no qual as ratas amamentaram seus filhotes por 3 semanas e os corações maternos foram, em seguida, submetidos à IR (n = 6); e não lactantes, no qual os filhotes foram separados após o nascimento e os corações maternos foram submetidos à IR (n = 6). As medidas de desfecho incluíram frequência cardíaca (FC), pressão desenvolvida no ventrículo esquerdo (PDVE), duplo produto (DP), razão do tamanho do infarto sobre a área sob risco (TI/ASR %) e arritmias ventriculares - contração ventricular prematura (CVP) e taquicardia ventricular (TV). Resultados: O TI/ASR foi substancialmente menor no grupo de lactantes quando comparado ao grupo de não lactantes (13,2 ± 2,5 versus 39,7 ± 3,5, p < 0,001) e ao grupo IR (13,2 ± 2,5 versus 34,0 ± 4,7, p < 0,05). A avaliação das arritmias ventriculares induzidas pela IR indicou que o número de CVPs compostas na isquemia, e o número e a duração das TVs na isquemia e nos primeiros 5 minutos de reperfusão no grupo de não lactantes foram significativamente (p < 0,05) mais elevados do que os encontrados nos grupos IR e de lactantes. Conclusão: A lactação induziu o aparecimento precoce de efeitos cardioprotetores, enquanto ratas que não foram permitidas a amamentar seus filhotes se mostraram mais suscetíveis à lesão miocárdica por IR.

Effect of Lactation on myocardial vulnerability to ischemic insult in rats.

Background: Cardiovascular diseases are the leading cause of mortality and long-term disability worldwide. Various studies have suggested a protective effect of lactation in reducing the risk of cardiovascular diseases. Objective: This study was designed to assess the effects of pregnancy and lactation on the vulnerability of the myocardium to an ischemic insult. Methods: Eighteen female rats were randomly divided into three groups: ischemia-reperfusion (IR), in which the hearts of virgin rats underwent IR (n = 6); lactating, in which the rats nursed their pups for 3 weeks and the maternal hearts were then submitted to IR (n = 6); and non-lactating, in which the pups were separated after birth and the maternal hearts were submitted to IR (n = 6). Outcome measures included heart rate (HR), left ventricular developed pressure (LVDP), rate pressure product (RPP), ratio of the infarct size to the area at risk (IS/AAR %), and ventricular arrhythmias - premature ventricular contraction (PVC) and ventricular tachycardia (VT). Results: The IS/AAR was markedly decreased in the lactating group when compared with the non-lactating group (13.2 ± 2.5 versus 39.7 ± 3.5, p < 0.001) and the IR group (13.2 ± 2.5 versus 34.0 ± 4.7, p < 0.05). The evaluation of IR-induced ventricular arrhythmias indicated that the number of compound PVCs during ischemia, and the number and duration of VTs during ischemia and in the first 5 minutes of reperfusion in the non-lactating group were significantly (p < 0.05) higher than those in the lactating and IR groups. Conclusion: Lactation induced early-onset cardioprotective effects, while rats that were not allowed to nurse their pups were more susceptible to myocardial IR injury.

Fundamento: As doenças cardiovasculares são a principal causa de mortalidade e invalidez a longo prazo a nível mundial. Diversos estudos têm sugerido um efeito protetor da lactação na redução do risco para doenças cardiovasculares. Objetivo: Este estudo foi desenvolvido para avaliar os efeitos da gestação e da lactação sobre a vulnerabilidade do miocárdio ao insulto isquêmico. Métodos: Dezoito ratas foram divididas aleatoriamente em três grupos: isquemia-reperfusão (IR), no qual os corações de ratas virgens foram submetidos à IR (n = 6); lactantes, no qual as ratas amamentaram seus filhotes por 3 semanas e os corações maternos foram, em seguida, submetidos à IR (n = 6); e não lactantes, no qual os filhotes foram separados após o nascimento e os corações maternos foram submetidos à IR (n = 6). As medidas de desfecho incluíram frequência cardíaca (FC), pressão desenvolvida no ventrículo esquerdo (PDVE), duplo produto (DP), razão do tamanho do infarto sobre a área sob risco (TI/ASR %) e arritmias ventriculares - contração ventricular prematura (CVP) e taquicardia ventricular (TV). Resultados: O TI/ASR foi substancialmente menor no grupo de lactantes quando comparado ao grupo de não lactantes (13,2 ± 2,5 versus 39,7 ± 3,5, p < 0,001) e ao grupo IR (13,2 ± 2,5 versus 34,0 ± 4,7, p < 0,05). A avaliação das arritmias ventriculares induzidas pela IR indicou que o número de CVPs compostas na isquemia, e o número e a duração das TVs na isquemia e nos primeiros 5 minutos de reperfusão no grupo de não lactantes foram significativamente (p < 0,05) mais elevados do que os encontrados nos grupos IR e de lactantes. Conclusão: A lactação induziu o aparecimento precoce de efeitos cardioprotetores, enquanto ratas que não foram permitidas a amamentar seus filhotes se mostraram mais suscetíveis à lesão miocárdica por IR.

Role of low-intensity laser therapy on naloxone-precipitated morphine withdrawal signs in mice: is nitric oxide a possible candidate mediator?

In the present study, the potential involvement of nitric oxide (NO) system in attenuating effects of low-intensity laser therapy (LILT) on naloxone-induced morphine withdrawal signs was evaluated. A hundred mice were rendered morphine-dependent using three escalating doses of morphine sulfate during three consecutive days. After the last dose on day 4, animals were given naloxone HCl (2 mg/kg s.c) to induce withdrawal signs. The effects of LILT (12.5 J/cm(2)) and L-NG-nitroarginine methyl ester (L-NAME) (10, 20, 50, and 100 mg/kg) and their coadministration on escape jump count and stool weight as typical withdrawal signs were assessed. LILT and L-NAME (20, 50, and 100 mg/kg) per se significantly decreased escape jump count and stool weight in morphine-dependent naloxone-treated mice (p < 0.01). Coadministration of LILT and L-NAME (20, 50, and 100 mg/kg) also reduced escape jump and stool weight (p < 0.05) but with no synergetic or additive response. Here, LILT at this fluence may show its maximal effects on NO and therefore no noticeable effects appeared during coadministration use. Moreover, LILT and L-NAME follow the same track of changes in escape jump and stool weight. Conceivably, it seems that LILT acts partly via NO system, but the exact path is still obscure and rather intricate. The precise mechanisms need to be clarified.

Trend of diseases among Iranian pilgrims during five consecutive years based on a Syndromic Surveillance System in Hajj.

BACKGROUND: Every year more than 2 million people depart from Iran to Saudi Arabia for Hajj ritual whichcan be faced with some different diseases. There are not much information about frequencies and trend of diseasesin Hajj. The main objective of this study was to determine the trend of prevalent diseases during five consecutiveHajj rituals among Iranian pilgrims. METHODS: We established a specific surveillance system for all Iranian pilgrims who had participated in Hajjfrom 2004 to 2008. We monitored the pilgrims' health status before departure, through their journey. The understudieddiseases were 19 selected types of diseases in the Hajj. The occurrences of diseases were recorded on aresearchers-made questionnaire. We used chi-square test for analysis with the alpha lower than 5% to reject thenull hypothesis. RESULTS: During 5 consecutive periods, a total of 254,823 of Iranian pilgrims were monitored for more commondiseases with this system. The most prevalent diseases were as follows: at least one type of respiratory involvement(71.26%), common cold like syndrome (47.15%), and musculoskeletal disorders (18.67%), The frequencyof respiratory involvement was lower in 2006 than other years (p <0.001).There were statistically significantdifferences between the numbers of hospitalization and patients who were referred back to Iran with theyear of Hajj (p <0.001). CONCLUSION: Health managers should be informed about trend and frequency of more prevalent diseases inHajj. Easy access to health information via such surveillance system can be possible.

The role of flaxseed and vitamin E on oxidative stress in prepubertal rats with experimental varicocele: An experimental study.

BACKGROUND: Prepubertal varicocele has the most devastating effects on the testes. Oxidative stress is the major cause leading to infertility in varicocele. The antioxidant properties of Flaxseed (FS) treatment in some oxidative diseases have been reported. OBJECTIVE: This study aimed to evaluate the antioxidant effect of FS in prepubertal rats with experimental varicocele. MATERIALS AND METHODS: Forty two male prepubertal rats were divided into 6 groups: the varicocele group were either fed with 10% FS, or with regular diet, or with Vit E, the group with sham operation fed with 10% FS, or had regular diet, and control rats who had not been operated but received regular diet. Varicocele was created by Koksal method. After 6 weeks sperm superoxide anion and H2O2 were evaluated by flowcytometery. Semen total antioxidant capacity (TAC) by Koracevic method and testes malondialdehyde (MDA) by thiobarbituric acid with spectrophotometry was measured. RESULTS: While superoxide anion and H2O2 were significantly higher in varicocele grop with regular diet (p=0.0001), FS significantly decreased the previously-mentioned parameters (p=0.0001). There were no significant differences for seminal TAC between 6 groups (p=0.07). Left testicular MDA concentration were lower in varicocele or group that were fed with 10% FS compared with other groups (p=0.001). CONCLUSION: Reactive oxygen species (ROS) may cause sperm oxidative damage. FS as a fat soluble antioxidant can scavenge intracellular ROS production in varicocele.

The synthesis and antifertility evaluation of 3 analogs of pyrimethamine on male rat reproductive indices.

Side effect assessment of medicaments on fertility indices may be used as a guide in the development of male contraceptive agents. In this study, 3 analogs of pyrimethamine were synthesized and evaluated for antifertility activity on reproductive indices of male rats. Test compounds were administered in a dosage of 50 mg/kg every other day till 60 days. On the 50th day, the fertility of rats was tested. On the 60th day, the gonadosomatic index and the serum testosterone content were determined. Iso-butyloxy and tertiary-butyloxy caused 40% and 11% reduction in sperm viability, respectively. They also significantly reduced fertility indices. Consequently, iso-butyloxy can be one of the best nominees in this class of compound and a suitable candidate for assessment of mechanism involved in future research activity. To synthesize a more effective agent, increasing the lipophilicity may play a major role in the development of more potent promising male contraceptive agents.

Flow cytometric evaluation of sperm superoxide anion production in rats with experimental varicocele.

OBJECTIVES: To determine whether intracellular superoxide anion production changes in the sperm of rats with experimental varicocele and to study mitochondrial membrane potential (MMP), sperm viability, antioxidant activity, Bax and Bcl-2 changes, and sperm count and motility in these rats. METHODS: The study groups consisted of 32 male rats divided into the following 4 groups: control, sham, varicocele-1, and varicocele-2. Experimental varicocele was established by partial ligation of the left renal vein in the latter 2 groups. Animals were killed 2 and 6 months after surgery, and dilation of the internal spermatic veins was observed. Then, superoxide anion production, MMP, antioxidant activity, and sperm characteristics were evaluated. Flow cytometry was used to study sperm superoxide anion production, assessed by dihydroethidium and MMP with rhodamine 123. RESULTS: Our results showed intracellular superoxide anion production significantly increased, and MMP, sperm viability, sperm count, and motility decreased in rats with experimental left varicocele. More Bax-positive cells were seen in the varicocele groups. However, there was no significant difference for seminal plasma antioxidant activity among all groups. CONCLUSIONS: These findings suggest that a main source of reactive oxygen species production in varicocele condition is intracellular.