Food deprivation and social inequality may lead to oxidative damage: a study on the preventive role of melatonin in the male rat reproductive system

Spermatogenic cells are susceptible to oxidative stress and apoptosis. Food deprivation (FD) has been reported as a stressor that could increase reactive oxygen species. In the present study, FD-induced oxidative stress and apoptosis, as well as the protective effects of melatonin, were evaluated in the testes. Wistar rats in the control group were fed a standard diet, whereas a sham group was administered saline as the melatonin vehicle. A third group received daily injections of melatonin (5mgkg-1 bodyweight). These rats were further divided into four groups of rats that were either subjected to FD, FD + isolation, FD + melatonin injection and FD + melatonin injection + isolation. Testicular tissues were evaluated for malondialdehyde (MDA) and reduced glutathione (GSH) concentrations, as well as and DNA damage. FD increased MDA and reduced GSH concentrations, whereas melatonin treatment improved these parameters. Immunohistochemistry for capsase-3 and terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling revealed that the number of apoptotic cells was increased in rats subjected to FD alone. Melatonin treatment offset the number of apoptotic cells following FD. The results provide evidence that FD can increase oxidative stress, leading to activation of apoptosis, and that melatonin has the ability to protect the testes against oxidative damage induced by FD.

Reversal of prenatal morphine exposure-induced memory deficit in male but not female rats

Impaired memory performance in offspring is one of the long-lasting neurobehavioral consequences of prenatal opiate exposure. Here, we studied the effects of prenatal morphine exposure on inhibitory avoidance memory performance in male and female offspring and also investigated whether these deficits are reversible during the postnatal development. Pregnant Wistar rats received morphine sulfate through drinking water, from the first day of gestation up to the day 13, M₁₋₁₃, or to the time of delivery, M₁₋₂₁. Four- and ten-week-old (adolescent and adult, respectively) male and female offspring were subjected to behavioral assays and then analysis of proteins involved in apoptosis or in synaptic plasticity. Results revealed that adolescent and adult female rats failed in passive avoidance retention task in both M₁₋₁₃ and M₁₋₂₁ groups. Adolescent and adult male offspring were similar to control animals in M₁₋₁₃ group. However M₁₋₂₁ impaired retention task in prepubertal male offspring, and this memory loss was repaired in postpubertal stage. Consistently, Bax/Bcl-2 ratio and cleaved caspase-3 were significantly increased in both M₁₋₁₃ and M₁₋₂₁ adolescent and adult female rats, but only in M₁₋₂₁ adolescent male rats. Furthermore, prenatal morphine exposure reduced the expression of brain-derived neurotrophic factor precursor protein in adolescent and adult female offspring and also decreased p-ca(2+)/calmodulin-dependent kinase II/ca(2+)/calmodulin-dependent kinase II ratio in adolescent male and female rats. Altogether, the results show that prenatal morphine exposure, depending on the time or duration of exposure, has distinct effects on male and female rats, and postnatal development may reverse these deficits more likely in males.

Cyclooxygenase (COX)-1 activity precedes the COX-2 induction in Aβ-induced neuroinflammation

Two different isoforms of cyclooxygenases, COX-1 and COX-2, are constitutively expressed under normal physiological conditions of the central nervous system, and accumulating data indicate that both isoforms may be involved in different pathological conditions. However, the distinct role of COX-1 and COX-2 and the probable interaction between them in neuroinflammatory conditions associated with Alzheimer's disease are conflicting issues. The aim of this study was to elucidate the comparable role of each COX isoform in neuroinflammatory response induced by β-amyloid peptide (Aβ). Using histological and biochemical methods, 13 days after stereotaxic injection of Aβ into the rat prefrontal cortex, hippocampal neuroinflammation and neuronal injury were confirmed by increased expression of tumor necrosis factor-alpha (TNF-α) and COX-2, elevated levels of prostaglandin E2 (PGE2), astrogliosis, activation of caspase-3, and neuronal cell loss. Selective COX-1 or COX-2 inhibitors, SC560 and NS398, respectively, were chronically used to explore the role of COX-1 and COX-2. Treatment with either COX-1 or COX-2 selective inhibitor or their combination equally decreased the level of TNF-α, PGE2, and cleaved caspase-3 and attenuated astrogliosis and neuronal cell loss. Interestingly, treatment with COX-1 selective inhibitor or the combined COX inhibitors prevented the induction of COX-2. These results indicate that the activity of both isoforms is detrimental in neuroinflammatory conditions associated with Aβ, but COX-1 activity is necessary for COX-2 induction and COX-2 activity seems to be the main source of PGE2 increment.

Effects of maternal oral morphine consumption on neural tube development in Wistar rats

Opiate abuse during pregnancy may result in abnormal nervous system function. In order to evaluate the effects of morphine on the development of the nervous system, the present study focused on the effects of maternal morphine consumption on neural tube development in Wistar rats. Female Wistar rats (250-300 g) were crossed with male rats and coupling time was recorded (embryonic day 0-E0). Experimental groups received 0.1, 0.05, and 0.01 mg/ml of morphine in drinking water daily (14 ml water for each rat). Control group received tap water. On embryonic day 9.5 (E9.5), the animals were anesthetized and the embryos were surgically removed. The embryos were fixed in 10% formalin for 1 week. After this time, weights and lengths (antero-posterior axis--A-P) of the embryos were determined and then tissues were processed, sectioned, and stained in hematoxylin and eosin (H&E). The sections were investigated for neural tube development by light microscope and MOTIC software. The decrease in "A-P" length and embryonic weight for the group that received 0.01 mg/ml morphine was significant. It seems that daily consumption of morphine sulfate could delay neural tube development. In addition, administration of 0.01 mg/ml of morphine led to damage to the regulated neuro-ectoderm layer and its thickness. This study showed that oral morphine consumption leads to neural tube defects, as indicated in the morphometric change and also reduction in weight and length of the embryos. These defects might affect the behavior of the animals.