Effects of maternal corticosterone and stress on behavioral and hormonal indices of formalin pain in male and female offspring of different ages

In previous studies, we showed for the first time that prenatal stress in rats produces long-term alterations of formalin-induced pain behavior that are dependent on age and sex, and we demonstrated an important role of the serotonergic system in mechanisms of prenatal stress (Butkevich, I.P. and Vershinina, E.A., 2001; Butkevich, I.P. and Vershinina, E.A., 2003; Butkevich, I.P., Mikhailenko, V.A., Vershinina, E.A., Khozhai, L.I., Grigorev, I.P., Otellin, V.A., 2005; Butkevich, I.P., Mikhailenko, V.A., Khozhai, L.I., Otellin, V.A., 2006). In the present study, we focus on the influence of the maternal corticosterone milieu and its role in the effects of stress during pregnancy on formalin-induced pain and the corticosterone response to it in male and female offspring of different ages. For this purpose, we used adrenalectomy (AD) in female rats 3-4 weeks before mating (as distinct from AD typically performed at the beginning of pregnancy). Since AD is considered a reliable method to treat hypercortisolism, researches on the effects of long-term AD in dams on the systems responsible for adaptive behavior in offspring are important (such studies are not described in the literature). The results demonstrate that the differences in the corticosterone response to injection of formalin and saline are obvious in 90-day-old (adult) female offspring but masked in 25-day-old ones. AD promoted the corticosterone response to formalin-induced pain but not to injection of saline in prenatally non-stressed female offspring of both ages. Prenatal stress canceled the differences in corticosterone response to injection of formalin and saline in 25-day-old offspring of AD dams and in adult offspring of sham-operated (SH) dams but caused similar differences in adult offspring of AD dams. Sex differences were found in basal corticosterone levels in AD prenatally stressed rats of both age groups, with a higher level in females, and in the corticosterone response to formalin-induced pain in the adult rats of all groups investigated, with higher corticosterone levels in females. In regard to pain behavior, AD induced significant changes in flexing + shaking in prenatally non-stressed adult offspring and canceled the differences in this behavior between non-stressed and stressed 25-day-old offspring. There were sex differences in pain behavior of the adult rats: greater flexing + shaking in AD non-stressed males but in SH non-stressed females; greater licking in prenatally-stressed AD and SH females. These results indicate that the long-term influences of maternal corticosterone on formalin-induced pain and the corticosterone response to it are determined by the sex and age of the offspring and suggest that other mechanisms, including serotonergic ones revealed in our previous studies, are involved in the effects of prenatal stress on inflammatory pain behavior.     

Alterations in serum and brain trace element levels after antidepressant treatment

We have studied the effect of chronic treatment with imipramine, citalopram and electroconvulsive shock (ECS) on serum and brain zinc levels in rats. Chronic treatment with citalopram (but not with imipramine or ECS) significantly (approx 20%) increased the serum zinc level. Chronic treatment with both drugs slightly (by approx 10%) increase the zinc level in the hippocampus and slightly decreased it in the cortex, cerebellum and basal forebrain. Calculation of the ratio hippocampus/brain region within each group demonstrated a significantly (approx 20%) higher value after treatment with either imipramine or citalopram. Moreover, chronic ECS induced a significant increase (by 30%) in the zinc level in the hippocampus and also a slight increase (by 11–15%) in the other brain regions. Thus, these different antidepressant therapies induced an elevation of the hippocampal zinc concentration, which indicates a significant role of zinc in the mechanism of antidepressant therapy.     

Altered corticosterone levels and social play behavior after prolonged maternal separation in adolescent male but not female Wistar rats

Early-life socio-environmental factors are crucial for normal developmental processes; adverse experiences early in life can therefore lead to detrimental effects in several physiological systems. The aim of this study was to examine short-term effects of early adverse experiences in a maternal separation (MS) rodent model. In this study two separation conditions were used: daily 15- (MS15) or 360-min (MS360) separation of the litter from the dam during postnatal day 1–21. In early adolescence, male and female offspring were subjected to a single-isolation procedure with analysis of corticosterone levels prior to and after isolation. In addition, social play behavior was assessed during mid-adolescence. There was a clear difference between male and female offspring in both tests performed. There was no difference in corticosterone levels between the female MS groups, whereas MS360 males showed higher baseline and recovery corticosterone levels than MS15 males. The amount of pinning, a specific social play behavior, was affected by rearing with MS360 males having a higher frequency than MS15 males, while there was no difference between the female MS groups. The observation that males but not females are affected by MS360 has previously been reported for adult animals, and herein we show that this difference is present already in adolescence. Changes in corticosterone levels and social behavior following early-life adversity have been associated with adult behavioral alterations, and our results confirm that these changes emerge already within adolescence.     

Postnatal development of rat pups after maternal exposure to diethanolamine

BACKGROUND: Diethanolamine (DEA), a widely used surfactant, was administered to pregnant mice at the oral LD10 resulting in failure of pups to grow and thrive through postnatal day (PND) 3 [National Toxicology Program, 1987; York et al., Teratology 37:503-504, 1988]. The toxicity profile for DEA differs among rodent species. This study investigated DEA-induced postnatal toxicity in a second species. METHODS: Timed-mated Sprague-Dawley rats were dosed (0, 50, 125, 200, 250, or 300 mg DEA/kg/day, p.o.) on gestational days (GD) 6-19. Dams and pups were monitored for body weight, feed/water intake, clinical signs, litter size, and sex ratio. At necropsy (PND 21), maternal liver and kidney weights and number of uterine implantation sites were recorded. RESULTS: The high-dose group was terminated early due to excessive toxicity. The estimated maternal LD10 was 218 mg/kg/day. Maternal effects included decreased body weight and relative feed intake (>or=200 mg/kg/day), transiently reduced relative water intake (125 and 250 mg/kg/day), and increased absolute kidney weight (>or=125 mg/kg/day). Postimplantation loss (PND 0) and pup mortality (PND 0-4) were increased (>or=200 and >or=125 mg/kg/day, respectively). Pup body weight was reduced (>or=200 mg/kg/day) as late as PND 21. CONCLUSIONS: This study demonstrates reduced postnatal growth and survival in a second species after gestational exposure to DEA, persistence of toxic effects through the end of lactation, possibly due to long elimination half-life, and maternal and developmental toxicity no-observed-adverse-effect level (NOAELs) (50 mg/kg/day) and lowest-observed-adverse-effect level (LOAELs) (125 mg/kg/day) for oral DEA exposure during embryo/fetal development in the rat.     

Cardiac microstructure in female and male offspring of exercised rat mothers

The microstructure of the cardiac muscle in eight subgroups of female and male rats was investigated: exercised (EE) and control (EC) offspring of exercised mothers, and exercised (CE) and control (CC) offspring of control, inactive mothers. The differences between subgroups were subjected to variance analysis and multiple-range tests according to Duncan. There were no marked differences in total body weight and weight of the heart related to total body weight. A significant difference (highest values) was shown in the density of muscle fibers and capillaries in the offspring of exercised mothers, which was further potentiated by the additional exercise during postnatal life. Diffusion distance was significantly longer in CC animals; the other subgroups did not differ significantly. There were no significant differences in the reaction of female and male offspring both due to prenatal and postnatal exercise.     

Normal levels of serum corticosterone and hepatic glucocorticoid receptors in obese (fa/fa) rats

In an attempt to understand the hyper-responsiveness to glucocorticoids that is characteristic of genetically obese fa/fa rats, we have measured the levels of free corticosterone in serum from lean and obese rats as well as the number of cytosolic and "nuclear" binding sites in livers of these rats. Both the lean and obese rats had similar amounts of free corticosterone available for biological activity at 4 weeks and 10 weeks of age. Measurement of glucocorticoid binding to hepatic glucocorticoid receptors failed to show any differences between genotypes leading to the suggestion that the abnormal glucocorticoid response in obese rats may be due either to post-receptor defects or to a permissive action of the steroid in the expression of the fa/fa genotype.     

Elevated oestrogen and reduced testosterone levels in the serum of male septic shock patients

The variations in oestrogen levels which occur in men with septic shock were determined and analysed in terms of the changes seen in the levels of other steroid hormones of testicular and adrenal origin. The concentrations of the hormones, oestrone (E1), oestradiol (E2), testosterone (T), delta 4-androstenedione (delta 4), cortisol (F) and progesterone (P4) were determined by radioimmunoassay. The serum levels of cholesterol, triglycerides, phospholipids and non-esterified fatty acids (NEFAs) were also determined. Two groups of male septic shock patients were studied within the first 24 h following the admission to the Intensive Care Unit. Group I (n = 24) patients died. Group II (n = 22) patients recovered. Both groups were compared to a control group (n = 44) of healthy men. In group I patients, serum E1 levels were 3900 +/- 900 pmol/l, 12-fold higher than controls (296 +/- 22 pmol/l) [P less than 0.001], serum E2 levels were 880 +/- 170 pmol/l, 6-fold above control levels (158 +/- 30 pmol/l) [P less than 0.001] and serum T levels were 1.7 +/- 0.3 nmol/l, 11-fold lower than in controls (18.7 +/- 1.9 nmol/l) [P less than 0.001]. Serum P4 and F levels were slightly increased (P less than 0.05) and delta 4 androstenedione levels were unchanged. Groups II serum estrogen levels (814 +/- 350 pmol/l) [P less than 0.01] were higher than controls and serum T levels were 2-3 times less than control levels (5.5 +/- 2 nmol/l) [P less than 0.01]. The group II serum P4, F and delta 4 androstenedione levels did not differ from control levels. The levels of cholesterol, triglycerides, phospholipids and NEFAs were all decreased to similar, significant, degrees in both groups of shock patients. The dramatic increase in E1 levels associated with the decrease in T suggests an adrenal-testicular relationship with possible potentiation of aromatization of adrenal or testicular androgens in men in septic shock. The determination of serum E1 and T during septic shock in men could form the basis for prognostic estimations of septic shock severity and for a new therapeutic approach to shock.     

Elevated corticosterone levels elicit non-calling mating tactics in male toads independently of changes in circulating androgens

Competition among males for a limited number of females may result in the expression of condition-dependent alternative mating tactics. In such cases, decision rules mediating mating tactic expression are likely to be influenced by a male's external as well as internal environment. For example, experimental studies with anuran amphibians (frogs and toads) indicate that changes in the social-acoustic environment alter the probability that an individual adopts a calling versus non-calling satellite mating tactic. However, there is considerable variation in the behavioral responses of individuals in such studies, suggesting that physiological differences among individuals play an important role in tactic expression. For instance, recent models predict that natural elevation in adrenal glucocorticoids during vocal production alters androgen production and/or neural activity to mediate transitions between reproductive tactic expression in anuran amphibians. Using corticosteroid injections, we show that elevation in circulating corticosterone levels significantly increase the probability that free-ranging male Great Plains toads (Bufo cognatus) and Woodhouse's toads (B. woodhousii) adopt a non-calling satellite tactic. Corticosterone-induced behavioral transitions occurred rapidly (<1 h) and independently of fluctuations in circulating androgen levels, suggesting a direct effect of glucocorticoids on brain centers controlling vocal production. We discuss our findings in the context of behavioral studies that alter the social-acoustic environment to examine its influence on tactic expression.     

Effects of corticosterone on protein, RNA, DNA and tubulin contents in developing male and female rat brains

The effects of corticosterone treatment on chemical components and tubulin content were studied in the cerebrum, cerebellum and hypothalamus from male and female rats during early life. A dual effect of corticosterone treatment was observed in the cerebellum during the course of growth. In the cerebellum from 10-day-old rats, total soluble protein. DNA, and tubulin content (mg per g wet tissue) increased in the hormone-treated male organ, but RNA, DNA, and tubulin content (mg per g wet tissue) increased in the hormone-treated female. On the other hand, the cerebellum from 20-day-old rats, RNA and tubulin content (mg per g wet tissue) and relative tubulin content (mg per g total protein) decreased in the hormone-treated male organ, but the female cerebellum exhibited a decrease in total protein and tubulin content (mg per g wet tissue), and relative tubulin content after corticosterone administration. Only a few effects of the corticosterone treatment were observed in the cerebrum and hypothalamus from both sexes. It is likely that corticosterone has marked effects on the cerebellum among the three brain-regions in early life, and the dual effect of the hormone in the cerebellum appears to be due to the different responsiveness in the developmental stages of nerve cells, at which the treatment was started.     

The effects of adrenalectomy and corticosterone replacement on induction of maternal behavior in the virgin female rat

Maternal behavior of the sensitized virgin rat is affected by approach-avoidance systems as well as by hypothalamic-pituitary-adrenal (HPA) axis, which is also activated during stress. The present experiments investigated the effects of adrenalectomy and of varying corticosterone concentrations on the onset and expression of maternal behavior in sensitized virgin rats. In the first experiment, latency to onset of maternal behavior and time spent licking once maternal were positively related to endogenous levels of corticosterone. However, few rats showed licking. In the second experiment, virgin rats were adrenalectomized or given sham surgeries before being sensitized and being given 0, 25, 100, 300, or 500 microg/mL of corticosterone in their drinking water. In the third experiment, virgin rats were adrenalectomized or given sham surgeries and given either control or corticosterone time-release pellets after being sensitized. Maternal behavior was then tested. Adrenalectomy increased licking in the second experiment and time over pups in the third experiment. Corticosterone replacement reduced licking in the second experiment and both licking and time over pups in the third experiment. In conclusion, exogenous corticosterone had an inhibitory effect on the expression of maternal behavior in the sensitized virgin rat, unlike the facilitatory effect previously found in the postpartum rat.     

Biodistribution and toxicity assessment of copper nanoparticles in the rat brain

AimsThe increase in the usage of copper nanoparticles (Cu NPs) in the industrial and medical fields has raised concerns about their possible adverse effects. The present study aims to investigate the potential adverse effects of Cu NPs on the brain of adult male Wistar rats through the estimation of some oxidative stress parameters and acetylcholinesterase (AChE) activity.Basic proceduresCu NPs were prepared and characterized using different techniques: Dynamic Light Scattering, X-Ray Diffraction, Transmission and Scanning Electron Microscopy, Fourier transform Infrared Spectroscopy, in addition to Energy Dispersive X-ray Spectroscopy. Rats were divided into two groups: Cu NPs-treated group (IV injected with 15 mg/kg ˷ 13 nm Cu NPs for 2 successive days) and a control group (injected with saline). Rats of the 2 groups were decapitated simultaneously after 48 h of the last injection. The Cu content in different brain areas was analyzed using inductively coupled plasma mass spectrometry. Moreover, the effect of Cu NPs on brain edema was evaluated. The behavior of rats in an open-field was also examined 24 h post the last injection.Main findingsSignificant increases of Cu content in the cortex, cerebellum, striatum, thalamus and hippocampus were found. Moreover, Cu NPs lead to the induction of oxidative stress condition in the thalamus, hypothamaus and medulla. In addition, Cu NPs induced significant increases in AChE activity in the medulla, hippocampus, striatum besides midbrain. Cu NPs-injected rats showed also decreased exploratory behaviour.Principal conclusionThe results obtained in the present study point to the importance of toxicity assessments in evaluating the efficiency of Cu NPs for the safe implementation in different applications.     

Effect of prolactin and glucocorticoids on P-enolpyruvate carboxykinase activity in liver and mammary gland from diabetic and lactating rats

Summary The administration of 2 bromo--ergocryptine, to reduce serum prolactin decreased the activity of cytosolic P-enolpyruvatc carboxykinase (GTP) (EC4.1.1.32) about 50% in both liver and mammary gland of lactating animals. Adrenalectomy had similar effects to those of bromo-a-ergocryptine. In contrast, there was a 50% increase in enzyme activity in the mammary gland of diabetic, lactating rats and a 10-fold increase in liver as compared with normal rats. P-enolpyruvate carboxykinase activity in mammary gland as liver is coordinately regulated by prolactin, glucocorticoids and insulin.     

Glucocorticoid regulation of glycerolphosphate dehydrogenase expression in the developing rat brain

Glucocorticoid regulation of glycerolphosphate dehydrogenase (GPDH) activity and gene expression in the developing rat brain appears complex throughout the postnatal developmental period and attains the adult pattern after the first month of life. GPDH enzyme activity is higher in the limbic system than in the cerebral cortex of intact young animals. Adrenalectomy of young rats, before the first month of life, does not affect GPDH enzyme activity in the brain areas mentioned above, while in the adult animals it results in a statistically significant decrease in activity. Furthermore, adult type glucocorticoid responsivity of GPDH enzyme activity is attained in the developing limbic system earlier — by day 40 of life — than in the cerebral cortex. During the first month of life, GPDH basal mRNA levels are increased in the absence of glucocorticoids, in both the limbic system and the cortex, in contrast to the effect of adrenalectomy in the adults, where GPDH mRNA levels are decreased in the absence of the adrenals. The observed pattern of glucocorticoid regulation of GPDH during development in the rat is discussed in relation to the possible existence of various levels of regulation of GPDH gene and enzyme activity.     

The effects of maternal corticosterone levels on offspring behavior in fast- and slow-growth garter snakes (Thamnophis elegans)

During embryonic development, viviparous offspring are exposed to maternally circulating hormones. Maternal stress increases offspring exposure to corticosterone and this hormonal exposure has the potential to influence developmental, morphological and behavioral traits of the resulting offspring. We treated pregnant female garter snakes (Thamnophis elegans) with low levels of corticosterone after determining both natural corticosterone levels in the field and pre-treatment levels upon arrival in the lab. Additional measurements of plasma corticosterone were taken at days 1, 5, and 10 during the 10-day exposure, which occurred during the last third of gestation (of 4-month gestation). These pregnant snakes were from replicate populations of fast- and slow-growth ecotypes occurring in Northern California, with concomitant short and long lifespans. Field corticosterone levels of pregnant females of the slow-growth ecotype were an order of magnitude higher than fast-growth dams. In the laboratory, corticosterone levels increased over the 10 days of corticosterone manipulation for animals of both ecotypes, and reached similar plateaus for both control and treated dams. Despite similar plasma corticosterone levels in treated and control mothers, corticosterone-treated dams produced more stillborn offspring and exhibited higher total reproductive failure than control dams. At one month of age, offspring from fast-growth females had higher plasma corticosterone levels than offspring from slow-growth females, which is opposite the maternal pattern. Offspring from corticosterone-treated mothers, although unaffected in their slither speed, exhibited changes in escape behaviors and morphology that were dependent upon maternal ecotype. Offspring from corticosterone-treated fast-growth females exhibited less anti-predator reversal behavior; offspring from corticosterone-treated slow-growth females exhibited less anti-predator tail lashing behavior.     

Protein-restricted maternal diet during lactation decreases type I and type III tropocollagen synthesis in the skin of mice offspring

We investigated the effects of a low protein (LP) maternal diet during lactation on type I and III tropocollagen synthesis in infant mouse skin. The LP diet decreased the levels of type I and III tropocollagen proteins and COL1A1 and COL3A1 mRNA. Thus, the protein composition of the maternal perinatal diet may influence the skin health of offspring.     

Immune response of male barn swallows in relation to parental effort, corticosterone plasma levels, and sexual ornamentation

Life-history theory posits trade-offs between fitness components. Reproduction negatively affects physiology and immune systemfunctioning, and the effect of this form of stress may be mediatedby glucocorticosteroids. We manipulated brood size of barnswallows (Hirundo rustica) to study the effect of stress arisingfrom reproductive effort on corticosterone levels of males.We also measured T-cell—mediated immunocompetence by intradermally injecting birds with phytohemagglutinin, whichis mitogenic to T-lymphocytes. The results confirmed the predictionof a negative effect of parental effort on lymphoproliferativeresponse. We found no covariation between immune response andcorticosterone levels. Males with long tails, an ornament currentlyunder directional sexual selection, had a relatively large T-cell response to the mitogen, consistent with models of parasite-mediated sexual selection predicting higher levels of immune defensein highly ornamented males. In addition, males with large sexualornaments had relatively low corticosterone levels at the endof the parental period. These results can be reconciled withthe hypothesis proposing a trade-off between parental activitiesand adaptive immunity and suggest that highly ornamented malesare less exposed or less susceptible to stress arising fromparental effort.