The effect of prenatal stress on activity of the neurosteroids synthesis enzyme in the "critical period" of brain sexual differentiation in male rats

The effect of daily immobillisation stress in female rats on the 15th to 18th days of pregnancy upon synthesis enzyme for neurosteroids of alpha-reductase in their male offspring brain, was studied. A decrease in the enzyme activity in the cortex and hypothalamus of male foetuses occurred within 24 hr following the latest stress, whereas it was increased in the cortex of newborn offspring. An enhancement of the 5 alpha-reductase activity in the cortex, hippocampus and hypothalamus was also found in prenatally stressed males on the 5th day of life. A decrease in the testosterone and progesterone contents in the blood plasma of the animals under study was revealed on the 19th day of their embryonic life as well as in newborn rats, the blood level of progesterone, at that, remained decreased even at the age of 5 days. A possible part ofneurosteroids in action of prenatal stress upon sexual differentiation of the brain is discussed.     

Changes in the neuroendocrine regulation of adaptive behavior in rats subjected to stress in the late prenatal ontogenesis]

Female rats were subjected from the 14th to 17th day of pregnancy to immobilisation under conditions of 1-hour daily bright illumination. On the 20th day, contents of testosterone and estradiol was decreased with no sex difference in their level in the pregnant female rats' blood and in the amniotic fluid. Sex differences were flattened in 1-month litter both in the androgen and oestrogen contents and in adaptive behaviour. In prenatally stressed males, motor activity was inhibited and anxiety was enhanced as compared with the control. At one and a half months of age, the consequences of the prenatal stress disappeared and then reappeared after sexual maturation but with an opposite trend. Adaptive behaviour of adult males was less flexible and revealed no age-dependent oscillations inherent in the control animals. Prenatal stress while preventing the maximal raise of sex steroids in the blood shifts sex differentiation of the adaptive behaviour toward demasculinization.     

Effect of prenatal stress on the hormonal response to acute and chronic stress and on immune parameters in the offspring

The effect of prenatal stress on the time course of the corticosterone response to acute and chronic stress and on hematological and immunological parameters in the offspring were analized in the present study. Pregnant Sprague-Dawley rats were stressed daily for 2 hours during the last week of gestation, and female and male off-spring were studied during adulthood. Corticosterone response to acute immobilization stress was not significantly different in either control or prenatally stressed rats. However, after 10 days of immobilization stress the corticosterone response completely disappeared in the control animals but not in the prenatally stressed group: high levels of corticosterone were found during the first hour of stress, although they were lower than those found in acutely stressed rats. Adrenal hypertrophy in response to prenatal stress was observed in females but not in male offspring, and chronic stress only increased adrenal weights in the male control group. Prenatal stress decreased the total peripheral leukocyte count, altered its diferential count decreasing lymphocytes and increasing neutrophil and eosinhophil counts, and significantly reduced the percentage of peripheral lymphocyte T CD8+ subset in male offspring. Chronic stress also reduced the percentage of the peripheral T CD8+ lymphocyte subset in the control group but not in the prenatally stressed group. These results suggest that the exposure to stress during pregnancy alters the adaptative response of the hypothalamus-pituitary-adrenocortical axis to chronic stress and presumably the immune competence in the offspring.     

Effect of testosterone on carboxypeptidase H activity in the murine hypothalamus and hypophysis

Effects of single intraperitoneal administration of testosterone propionate (3 or 30 mg/kg body weight) on activity of carboxypeptidase H in pituitary body and hypothalamus of female white mouse were studied. It was found that testosterone propionate treatment (3 and 30 mg/kg body weight) increased the carboxypeptidase H activity in pituitary through 0.5 hour and it decreased one in 24 hours after treatment. The carboxypeptidase H activity in hypothalamus was lower as compared with control animals in 24 hours after testosterone propionate treatment in the dose 3 mg/kg body weight. However, the carboxypeptidase H activity in hypothalamus was lower in 0.5 and 24 hours and it was higher in 4 h after testosterone propionate treatment in the dose 30 mg/kg body weight as compared with the control. These data suggest that testosterone affects the carboxypeptidase H activity by changing the level of enzyme gene expression.     

Influence of prenatal stress on the rat hypothalamic-pituitary-adrenal axis activity: the role of the brain glycocorticoid receptors

The effects of prenatal stress on the hypothalamic-pituitary-adrenal (HPA) axis activity and brain glycocorticoid receptors were studied in neonatal male and female offspring, as well as the influence of neonatal glycocorticoid receptors blockade on hormonal stress reactivity of adult rats. The results showed that there were sexual differences in plasma corticosterone level and corticosteroid binding in the cortex and hypothalamus of 5-day old control rats. Prenatal stress increased basal level of corticosterone in female rats, decreased corticosterone binding in hypothalamus and hippocampus of male and female rats, and increased corticosteroid receptor level in the male cortex. Neonatal administration of glycocorticoid receptor antagonist did not change plasma corticosterone level in 5-day old rats, but prolonged hormonal stress response of the HPA axis in adult male rats and increased hormonal stress response in female ones. The character of the IIPA axis activity of male and female rats with neonatal blockade of glycocorticoid receptors correspond to hormonal stress response of prenatal stressed rats. These data suggest that change of brain glycocorticoid receptors function in neonatal period of development might be one of the mechanisms of prenatal stress influence on the HPA axis activity in the adulthood.     

The effect of "social stress" during rat pregnancy on the anxiety level of the progeny

Anxiety and locomotion were studied in offsprings of female rats subjected to everyday stress (one a day being displaced into another cage with pregnant rats) during the 3d stage of pregnancy. At the age of 1 month, the prenatally stressed rats had higher anxiety and lower locomotion in comparison with control animals. At the age of 3 month, the prenatally stressed females did not significantly differ from the control in the level of anxiety and locomotion, while the males demonstrated lower ambulation than the control animals.     

Effect of testosterone and progesterone on carboxypeptidase H activity in the hypothalamo-hypophyseal-gonadal axis and the adrenal gland in mice

Testosterone propionate decreased activity of carboxypeptidase H in the male mongrel mice pituitary gland, activity of the CP H in testicles, and increased these parameters in 4 hours after treatment. Progesterone decreased the CP H activity in pituitary gland and increased it in testicles. Progesterone increased the CP H activity in female pituitary gland and decreased it in adrenal gland and hypothalamus. The role of the CP H in the effects of the sex steroids on the function of peptidergic systems is discussed.     

Neuroendocrine reactions to intracerebroventricular injections of arginine-vasopressin in prenatally stressed rats

We studied the effect of central vasopressinergic stimulation on the functions of the hypothalamo-pituitary-adrenal and hypothalamo-pituitary-gonadal axes in mature offsprings of female rats stressed during the last week of pregnancy (daily immobilization for 1 h). Experiments were carried out on unanesthetized rats; the blood samples were taken 20 and 40 min after intracerebroventricular injections of arginine-vasopressin (AVP). Twenty minutes after infusion of 0.5 ng of this neuropeptide dissolved in 2 μl of isotonic NaCl solution into the III cerebral ventricle, the adrenocortical reaction in prenatally stressed males was 50% smaller than that in normal animals; on the 40th min, it continued to develop but remained weaker. In prenatally stressed females, the adrenocortical reaction to central vasopressinergic stimulation was weakened. Arginine-vasopressin-induced increases in the level of corticotropin in the blood were nearly identical in both prenatally stressed and normal rats (males and females). The level of testosterone in the blood of prenatally stressed and normal males dropped sharply 20 min after intracerebroventricular injection of AVP and, on the 40th min, remained significantly lower than the basal level in males of both studied groups; prenatal stress did not influence these alterations. Our data show that vasopressinergic control is weakened in prenatally stressed male rats, and this is a significant probable reason for the decrease in the stress reactivity of the hypothalamo-pituitary-adrenal system in these animals. Neirofiziologiya/Neurophysiology, Vol. 39, No. 6, pp. 453–457, November–December, 2007.     

Sex differences impact the pancreatic response to chronic immobilization stress in rats

Chronic stress has been related to multiple diseases. Inflammation is proposed strongly to link stress to stress-related diseases in different organs, such as small intestine, colon, and brain. However, stress cellular effect on the pancreatic tissue, especially the exocrine one, had received relatively little attention. This work aimed to evaluate the cellular effect of chronic immobilization stress on the pancreatic tissue function and structure along with evaluating the sex role in this type of pancreatic injury. Thirty rats were equally divided into 5 groups: control male, control female, stressed male, stressed female, and stressed female with bilateral ovariectomy. Stressed rats were exposed to immobilization for 1 h/day, 6 days/week, for 3 weeks. Rats were then decapitated for further biochemical, histological, histo-morphometric, and immunohistochemical study. The results showed that, in male and female rats, chronic immobilization stress produced hypoinsulinemia and hyperglycemia, with increasing exocrine pancreatic injury markers by increasing oxidative and inflammatory status of the pancreatic tissue, and exhibited a degenerative effect on the pancreatic tissue. However, the stress-induced pancreatic effects were more obvious in male rats and female rats with bilateral ovariectomy than that in female rats. It could be concluded that male animals were more susceptible to stress-induced pancreatic damage than females. The ovarian hormones are responsible, at least partly, for pancreatic tissue protection since the stress-induced pancreatic injury in females was exacerbated by ovariectomy. In this study, inflammatory and oxidative stress differences in both sexes could provide a plausible explanation for sex differences.     

Long-term effects of stress in critical periods of development on reactivity of adult female rats

Effects of stress during different periods of ontogeny, namely, the prenatal, prepubertal, or their combination (prenatal+prepubertal), on the indices of psychoemotional and tonic pain-related behaviors, as well as corticosterone reactivity after pain behavior were investigated in adult 90-day-old female Wistar rats. Our data show for the first time, the similarity of effects of prenatal (immobilization stress of a rat dam during the last week of pregnancy) and prepubertal (forced swimming, pain-related response in the formalin test) stresses on the indices under study, an increase in the time of immobility and in licking duration, but the difference between effects of combined stress on these indices. Pain-related response increased corticosterone in prepubertally stressed rats while in prenatally stressed rats, decreased it. In rats experienced combined stress, formalin-induced pain increased corticosterone as compared with that in prenatally, but not in prepubertally stressed rats. A positive correlation between pain-related reaction and stressed hormonal response was revealed in prepubertally stressed animals. So, long-term effects of stress during critical periods of ontogeny determine stress reactivity of behavioral and hormonal responses in adult female rats.     

Prenatal stress alters circadian activity of hypothalamo-pituitary-adrenal axis and hippocampal corticosteroid receptors in adult rats of both gender.

Prenatal stress impairs activity of the hypothalamo-pituitary-adrenal (HPA) axis in response to stress in adult offspring. So far, very few data are available on the effects of prenatal stress on circadian functioning of the HPA axis. Here, we studied the effects of prenatal stress on the circadian rhythm of corticosterone secretion in male and female adult rats. To evaluate the effects of prenatal stress on various regulatory components of corticosterone secretion, we also assessed the diurnal fluctuation of adrenocorticotropin, total and free corticosterone levels, and hippocampal corticosteroid receptors. Finally, in the search of possible maternal factors, we studied the effects of repeated restraint stress on the pattern of corticosterone secretion in pregnant female rats. Results demonstrate that prenatal stress induced higher levels of total and free corticosterone secretion at the end of the light period in both males and females, and hypercorticism over the entire diurnal cycle in females. No diurnal fluctuation of adrenocorticotropin was observed in any group studied. The effects of prenatal stress on corticosterone secretion could be mediated, at least in part, by a reduction in corticosteroid receptors at specific times of day. Results also show that prepartal stress alters the pattern of corticosterone secretion in pregnant females. Those data indicate that prenatally stressed rats exhibit an altered temporal functioning of the HPA axis, which, taken together with their abnormal response to stress, reinforces the idea of a general homeostatic dysfunction in those animals.     

Sensitiveness to social stress in female rats with alteration of the pituitary-adrenal axis stress reactivity

The sensitiveness of female rats to social stress induced by increasing group density, was investigated. It was shown that female rats were housed in groups of 9-10 animala per cage in pubertal period and demonstrated significant alteration of oestrous cycle duration and anxiety level. This housing condition increased basal level of corticostcrone in prenatal stressed female rats who have high stress reactivity of the hypothalamic-pituitary-adrenal axis, as well as a more profound effect on anxiety level and oestrous cycle. Prenatal stressed rats retained impairment of oestrous cycle and behavior after optimization of housing condition, whereas control rats demonstrated normalization of oestrous cycle duration and anxiety level. These data suggest that high stress reactivity females rats are more sensitive to crowding-induced stress.     

Responses of the hypothalamic-pituitary-adrenal axis to noradrenergic and hormonal stimulation in prenatally stressed rats

We studied the effects of maternal stress (the so-called prenatal stress, PS, provided by immobilization of pregnant female Wistar rats for 1 h daily during the 15–21st gestational days) on the corticosterone response in the blood plasma evoked by infusion of 10 μg noradrenaline bitartrate into the III cerebral ventricle or by injection of β-1-24-corticotropin in 3-month-old male and female offspring. The animals were bearing an intracerebroventricular stainless steel guide cannula implanted eight to nine days before the experiment, and a Silastic catheter inserted into the external jugular vein 24 h prior to the experiment. Blood samples were periodically taken from conscious unrestrained rats (before and then 30, 60 and 90 or 120 min after noradrenaline or corticotropin challenge). In the male offspring PS augmented and prolonged an increase in the plasma corticosterone level resulting from adrenergic stimulation of the hypothalamus, as compared with that in non-stressed animals. In prenatally stressed female offspring tested in diestrus, there was no response of the hypothalamic-pituitary-adrenal (HPA) axis to intracerebroventricular noradrenaline stimulation, in contrast to what was observed in the control. Prenatal stress did not modify the adrenal cortex responsiveness to corticotropin either in male or in female offspring. The results demonstrate differential effects of PS on the adrenergic activation of the HPA axis in males and females. A decrease in the acute HPA stress-responsiveness in prenatally stressed male rats, which was demonstrated in an earlier study, and the maintenance or even enhancement of this effect in prenatally stressed females are not likely to be connected with the state of hypothalamic adrenergic reactivity.     

Characterization of depression-like behavior in prenatally stressed female rats during ovary cycle

The aim of the present work was a comparative analysis of dynamics of depression-like behavior in prenatally stressed and non-prenatally stressed female rats in the key phases of the ovary cycle. It was found that non-stressed female rats demonstrated high level of depression-like behavior in proestrous phase as compared to the diestrous phase, whereas these rats showed low level of depression-like behavior in estrous phase in Porsolt's test. On the contrary, there were no significant differences in extent of depression-like behavior between prenatally stressed rats in the diestrous and proestrous, although in the phase of estrous in these animals an increase in level of depression-like behavior was noted. Thus, the results of this study indicated pronounced effects of prenatal stress on the character of depression-like behavior of females in different phases of ovary cycle. This study revealed leveling and reversed action of prenatal stress on depression-like behavior in key phases of sexual cycle in female rats.     

Interactions Between Chronic Stress and Chronic Consumption of Caffeine on the Enzymatic Antioxidant System

We studied the effect of chronic caffeine on parameters related to oxidative stress in different brain regions of stressed and non-stressed rats. Wistar rats were divided into three groups: control (receiving water), caffeine 0.3 g/L and caffeine 1.0 g/L (in the drinking water). These groups were subdivided into non-stressed and stressed (repeated restraint stress during 40 days). Lipid peroxide levels and the total radical-trapping potential were assessed, as well as antioxidant enzyme activities superoxide dismutase, gluthatione peroxidase, and catalase in hippocampus, striatum and cerebral cortex. Results showed interactions between stress and caffeine, especially in the cerebral cortex, since caffeine increased the activity of some antioxidant enzymes, but not in stressed animals. We concluded that chronic administration of caffeine led, in some cases, to increased activity of antioxidant enzymes. However, these effects were not observed in the stressed animals.     

Modification of expression of neurohormones in hypothalamus of prenatally stressed male rats in model of posttraumatic stress disorder

By the method of quantitative immunohistochemistry there has been studied expression of corticotrophin-releasing hormone (CRH) and vasopressin in hypothalamic paraventricular nucleus (PVN) of prenatally stressed rats in the experimental model of the posttraumatic stress disorder-the paradigm “stress-restress”. The prenatal stress was modeled by immobilization of pregnant female rats for 1 h from the 15th to the 19th day of pregnancy. It has been shown that in sexually mature males-descendants of stressed mothers-a decrease in immunoreactivity to CRH and vasopressin is observed in the parvocellular and magnocellular PVN areas 10 days after the restress. In the control group males born by intact mothers the level of immunoreactivity to CRH was increased in both PVN areas, whereas with respect to vasopressin-in the magnocellular area. Only in the prenatally stressed males there is detected a decrease in the corticosterone level in the blood plasma 10 days after the restress. It is concluded that in the control group males the manifestation of the pathological state in the paradigm “stress-restress” consists in hyperactivation of the hypothalamic chain of regulation of the hypothalamus-pituitary-adrenocortical system, whereas in the prenatally stressed animals, on the contrary, there is observed a decrease in activity both of the central (PVN) and of the peripheral (adrenal cortex) chain of this hormonal axis.     

Anxiety induced by prenatal stress is associated with suppression of hippocampal genes involved in synaptic function

Exposure of pregnant women or animals to stress during a critical period of foetal brain development increases the likelihood of anxiety, depression and learning deficits that are associated with structural alterations in the offspring hippocampus. In this study, we report the effect of gestational stress in rats on anxiogenic behaviour and hippocampal gene expression of their 23-day-old female offspring. As the rat brain continues to develop after birth, we also used the procedure of handling (H) during the first 10 days of life to reverse the anxiogenic behaviour of prenatally stressed (PS) rats. By means of micro-array analysis on hippocampal extracts, we found that the expression of about 6.1% of 9505 valid genes was significantly altered by prenatal stress (p<0.05). Of these, 48% were over-expressed and 52% under-expressed. The latter included approximately 300 genes that participate in axonal growth, regulation of ion channels and transporters, trafficking of synaptic vesicles and neurotransmitter release. About 30% of the genes that were down-regulated in PS rats were restored to control levels by H. These include genes that play a role in pre-synaptic organization and function. Our results provide a possible relationship between hippocampal gene expression and changes in behaviour resulting from prenatal stress.     

Effect of testosterone and progesterone on carboxypeptidase H activity during stress in mice

It was found that testosterone propionate (3 mg/kg of body weight) and progesterone (1 mg/kg of body weight) partially prevent an augmentation of the carboxypeptidase H activity in the mouse pituitary gland under stress caused by a single intraperitoneal administration of olive oil. In testicles, testosterone prevented augmentation of the enzyme activity within 0.5 hours but increased it through in 4 and 24 hours after treatment. Progesterone in testicles augmented the enzyme activity within 0.5 hours, but not in 4 and 24 hours. Sex steroids were not affected by stressinduced carboxypeptidase H activity in hypothalamus and adrenal medulla. It was concluded that carboxypeptidase H did not take part in integration of hypothalamus-pituitary-adrenal and hypothalamus-pituitary-gonadal axis under the stress.     

Prenatal stress alters circadian activity of hypothalamo–pituitary–adrenal axis and hippocampal corticosteroid receptors in adult rats of both gender

Prenatal stress impairs activity of the hypothalamo–pituitary–adrenal (HPA) axis in response to stress in adult offspring. So far, very few data are available on the effects of prenatal stress on circadian functioning of the HPA axis. Here, we studied the effects of prenatal stress on the circadian rhythm of corticosterone secretion in male and female adult rats. To evaluate the effects of prenatal stress on various regulatory components of corticosterone secretion, we also assessed the diurnal fluctuation of adrenocorticotropin, total and free corticosterone levels, and hippocampal corticosteroid receptors. Finally, in the search of possible maternal factors, we studied the effects of repeated restraint stress on the pattern of corticosterone secretion in pregnant female rats. Results demonstrate that prenatal stress induced higher levels of total and free corticosterone secretion at the end of the light period in both males and females, and hypercorticism over the entire diurnal cycle in females. No diurnal fluctuation of adrenocorticotropin was observed in any group studied. The effects of prenatal stress on corticosterone secretion could be mediated, at least in part, by a reduction in corticosteroid receptors at specific times of day. Results also show that prepartal stress alters the pattern of corticosterone secretion in pregnant females. Those data indicate that prenatally stressed rats exhibit an altered temporal functioning of the HPA axis, which, taken together with their abnormal response to stress, reinforces the idea of a general homeostatic dysfunction in those animals. © 1999 John Wiley & Sons, Inc. J Neurobiol 40: 302–315, 1999     

Effect of chloroform and ether narcosis on the activity of basic carboxypeptidases in the hypothalamic-pituitary-adrenal axis in rats

It is discovered that chloroform narcosis does not influence on carboxypeptidase H and phenylmethylsulfonyl fluoride-inhibited carboxypeptidase activity in the rats hypothalamic-pituitary-adrenal axis. Ether narcosis provokes an increase of PMSF-inhibited carboxypeptidase activity in the pituitary body approximately in 8 times and carboxypeptidase H activity in hypothalamus by 29 percents in comparison with the intact animals. It is supposed that at research neuropeptides and their metabolism enzymes and especially the answer to a stress chloroform narcosis would be the better anaesthesia method than ether narcosis.