The maturational characteristics of the GABA input in the anterior piriform cortex may also contribute to the rapid learning of the maternal odor during the sensitive period.

During the first ten postnatal days (P), infant rodents can learn olfactory preferences for novel odors if they are paired with thermo-tactile stimuli that mimic components of maternal care. After P10, the thermo-tactile pairing becomes ineffective for conditioning. The current explanation for this change in associative learning is the alteration in the norepinephrine (NE) inputs from the locus coeruleus (LC) to the olfactory bulb (OB) and the anterior piriform cortex (aPC). By combining patch-clamp electrophysiology and computational simulations, we showed in a recent work that a transitory high responsiveness of the OB-aPC circuit to the maternal odor is an alternative mechanism that could also explain early olfactory preference learning and its cessation after P10. That result relied solely on the maturational properties of the aPC pyramidal cells. However, the GABAergic system undergoes important changes during the same period. To address the importance of the maturation of the GABAergic system for early olfactory learning, we incorporated data from the GABA inputs, obtained from in vitro patch-clamp experiment in the aPC of rat pups aged P5-P7 reported here, to the model proposed in our previous publication. In the younger than P10 OB-aPC circuit with GABA synaptic input, the number of responsive aPC pyramidal cells to the conditioned maternal odor was amplified in 30% compared to the circuit without GABAergic input. When compared with the circuit with other younger than P10 OB-aPC circuit with adult GABAergic input profile, this amplification was 88%. Together, our results suggest that during the olfactory preference learning in younger than P10, the GABAergic synaptic input presumably acts by depolarizing the aPC pyramidal neurons in such a way that it leads to the amplification of the pyramidal neurons response to the conditioned maternal odor. Furthermore, our results suggest that during this developmental period, the aPC pyramidal cells themselves seem to resolve the apparent lack of GABAergic synaptic inhibition by a strong firing adaptation in response to increased depolarizing inputs.

The Impact of Oxytocin Gene Knockout on Sexual Behavior and Gene Expression Related to Neuroendocrine Systems in the Brain of Female Mice.

Social relations are built and maintained from the interaction among individuals. The oxytocin (OT), vasopressin (VP), estrogen, dopamine, and their receptors are involved in the modulation of sexual behavior in females. This study aimed to analyze the impact of OT gene knockout (OTKO) on sexual behavior and the gene expression of oxytocin (OTR), estrogen alpha (ERα), estrogen beta (ERß), vasopressin (V1aR), and dopamine (D2R) receptors in the olfactory bulb (OB), prefrontal cortex (PFC), hippocampus (HPC), and hypothalamus (HPT), as well as in the synthesis of VP in the HPT of female mice. Wild-type (WT) littermates were used for comparisons. The CDNAs were synthesized by polymerase chain reaction and the gene expression was calculated with the 2-ΔΔCt formula. Our results showed that the absence of OT caused an increase in the frequency and duration of non-receptive postures and a decrease in receptive postures in the OTKO. OTKO females showed a significant decrease in the gene expression of OTR in the HPC, V1aR in the HPT, and ERα and ERß in the PFC. There was no significant difference in the gene expression of D2R of OTKO. However, OTKO showed an increased gene expression of V1aR in the HPC. There is no significant difference in VP mRNA synthesis in the HPT between OTKO and WT. Our findings demonstrate that the absence of OT leads to significant changes in the expression of the studied genes (OTR, ERα, ERß, V1aR), and these changes may contribute to the decreased sexual behavior observed in OTKO females.

Prenatal stress produces social behavior deficits and alters the number of oxytocin and vasopressin neurons in adult rats.

The present study investigated the long-lasting effects of prenatal repeated restraint stress on social behavior and anxiety, as well as its repercussions on oxytocin (OT) and vasopressin (VP)-positive neurons of the paraventricular (PVN) and supraoptic (SON) nuclei from stressed pups in adulthood. Female Wistar rats were exposed to restraint stress in the last 7 days of pregnancy. At birth, pups were cross-fostered and assigned to the following groups: prenatally non-stressed offspring raised by prenatally non-stressed mothers (NS:NS), prenatally non-stressed offspring raised by prenatally stressed mothers (S:NS), prenatally stressed offspring raised by prenatally non-stressed mothers (NS:S), prenatally stressed offspring raised by prenatally stressed mothers (S:S). As adults, male prenatally stressed offspring raised both by stressed mothers (S:S group) and non-stressed ones (NS:S group) showed impaired social memory and interaction. In addition, when both adverse conditions coexisted (S:S group), increased anxiety-like behavior and aggressiveness was observed in association with a decrease in the number of OT-positive magnocellular neurons, VP-positive magnocellular and parvocellular neurons of the PVN. The NS:S group exhibited a reduction in the amount of VP-positive magnocellular neurons compared to the S:NS. Thus, the social behavior deficits observed in the S:S and NS:S groups may be only partially associated with these alterations to the peptidergic systems. No changes were shown in the OT and VP cellular composition of the SON nucleus. Nevertheless, it is clear that a special attention should be given to the gestational period, since stressful events during this time may be related to the emergence of behavioral impairments in adulthood.

Neonatal handling induces deficits in infant mother preference and adult partner preference.

Neonatal handling is an experimental procedure used to understand how early-life adversity can negatively affect neurobehavioral development and place animals on a pathway to pathology. Decreased preference for the maternal odor during infancy is one of many behavioral deficits induced by neonatal handling. Here, we hypothesize that deficits in maternal odor preference may interfere with partner preference in the adult. To test this hypothesis, we assessed infant maternal odor preference and adult partner preference in different reproductive stages in both male and female rats that received neonatal handling. Our results indicate that only neonatally handled females present deficits in maternal odor preference during infancy, but both male and females present deficits in adult partner preference. However, sexual experience was effective in rescuing partner preference deficits in males. These results indicate that, considering infant and adult social interactions, females are more susceptible to the effects of neonatal handling than males.

The role of AT1 receptor-mediated reproductive function in renovascular hypertension in male rats.

There is an association between hypertension and reproductive dysfunction. Angiotensin II (Ang II) is involved in the pathogenesis of hypertension and the regulation of reproduction. The present study aimed to determine whether the angiotensinergic system mediates the effects of hypertension on reproductive function in male rats subjected to a two-kidney, one-clip (2K1C) model. Sexual behavior parameters, gametogenesis and plasma concentrations of Ang II, testosterone, prolactin and corticosterone were evaluated in male rats 28days after 2K1C or sham surgery and losartan (Los) treatment (a type 1 angiotensin II (AT1) receptor antagonist) or vehicle (V) treatment. The animals were divided into Sham+V, 2K1C+V, Sham+Los and 2K1C+Los groups. The 2K1C+V group showed a hypertensive response, inhibition of sexual behavior, spermatogenesis dysfunction, and increases in plasma Ang II and prolactin. Conversely, plasma testosterone decreased, and plasma corticosterone remained constant. Losartan treatment normalized blood pressure and prevented the changes in plasma testosterone and prolactin, sexual behavior and spermatogenesis in the 2K1C+Los group. In addition, losartan treatment caused an additional increase in circulating Ang ll in both groups (Sham+Los and 2K1C+Los). Together, these results suggest that Ang ll, acting through the AT1 receptor, modulates behavioral and endocrine parameters of reproductive function during renovascular hypertension. In addition, the effects of circulating Ang II on plasma testosterone and prolactin seem to contribute to the spermatogenic and sexual dysfunctions in hypertensive rats.

Brain-derived neurotrophic factor levels in women with postpartum affective disorder and suicidality.

Our aim was to investigate serum brain-derived neurotrophic factor (BDNF) levels in postpartum women, according to the presence of postpartum affective disorder (PPAD) and suicidality. A cross-sectional study was carried out with women between 45 and 90 days after delivery. PPAD (depression, manic and mixed episode) and suicide risk were assessed using the Mini International Neuropsychiatric Interview. BDNF was assessed using a commercial ELISA kit. Linear regression was used for multivariate analyses. A hundred ninety women participated in the study, 15.3 % had PPAD, 7.4 % showed PPAD with suicide risk. BDNF levels were lower in subjects with three or more Stressful Life Events (P = 0.01). The serum BDNF levels of women with PPAD presenting suicide risk were significantly lower than those of women without suicide risk (1.50 ± 1.38 and 2.33 ± 1.28 ng/ml, P = 0.02). Clinicians should enquire postpartum women about their history of stressful life events, PPAD, and suicidality. This study shows the potential role of BDNF in the neurobiology of the association of PPAD and suicidality.

Association between Na⁺,K⁺-ATPase activity and the vulnerability/resilience to mood disorders induced by early life experience.

There is increasing evidence that early life events can influence neurodevelopment and later susceptibility to disease. Chronic variable stress (CVS) has been used as a model of depression. The objective of this study was to evaluate the interaction between early experience and vulnerability to chronic variable stress in adulthood, analyzing emotional, metabolic and neurochemical aspects related to depression. Pups were (1) handled (10 min/day) or (2) left undisturbed from day 1 to 10 after birth. When the animals reached adulthood, the groups were subdivided and the rats were submitted or not to CVS, which consisted of daily exposure to different stressors for 40 days, followed by a period of behavioral tasks, biochemical (plasma corticosterone and insulin sensitivity) and neurochemical (Na⁺,K⁺-ATPase activity in hippocampus, amygdala and parietal cortex) measurements. Neonatally-handled rats demonstrated shorter immobility times in the forced swimming test, independently of the stress condition. There was no difference concerning basal corticosterone or insulin sensitivity between the groups. Na⁺,K⁺-ATPase activity was decreased in hippocampus and increased in the amygdala of neonatally-handled rats. CVS decreased the enzyme activity in the three structures, mainly in the non-handled group. These findings suggest that early handling increases the ability to cope with chronic variable stress in adulthood, with animals showing less susceptibility to neurochemical features associated with depression, confirming the relevance of the precocious environment to vulnerability to psychiatric conditions in adulthood.

Effects of neonatal handling on social memory, social interaction, and number of oxytocin and vasopressin neurons in rats.

Early-life environmental events can induce profound long-lasting changes in several behavioral and neuroendocrine systems. The neonatal handling procedure, which involves repeated brief maternal separations followed by experimental manipulations, reduces stress responses and sexual behavior in adult rats. The purpose of this study was to analyze the effects of neonatal handling on social behaviors of male and female rats in adulthood, as manifest by the results of social memory and social interaction tests. The number of oxytocin (OT) and vasopressin (VP) neurons in the paraventricular (PVN) and supraoptic (SON) nuclei of hypothalamus were also analyzed. The results did not demonstrate impairment of social memory. Notwithstanding, handling did reduce social investigative interaction and increase aggressive behavior in males, but did not do so in females. Furthermore, in both males and females, handling was linked with reduced number of OT-neurons in the parvocellular region of the PVN, while no differences were detected in the magnocellular PVN or the SON. On the other hand, handled males exhibited increased number of VP-neurons in the magnocellular zone of the PVN. We may conclude that the repeated brief maternal separations can reduce affiliative social behavior in adult male rats. Moreover, the disruption of the mother-infant relationship caused by the handling procedure induced long-lasting morphological changes in critical neuroendocrine areas that are involved in social bonding in mammals.

Neonatal handling reduces renal function in adult rats.

BACKGROUND/AIMS: To evaluate the effects of neonatal handling on hydroelectrolytic balance in adult rats. METHODS: The litters were divided into two groups: nonhandled and handled. The procedure consisted of handling the pups for 1 min/day in the first 10 days postnatally. When adults, animals had their body weight verified and were housed in individual metabolic cages. After a 24-hour period, urine samples were collected and the urinary and water intake volumes measured. Blood samples to determine osmolality, aldosterone, corticosterone, angiotensin II, creatinine, urea, sodium and potassium levels were collected. The kidneys were removed for histological assessment. Urinary osmolality, sodium, urea and creatinine were also measured and the creatinine clearance (CC) calculated. RESULTS: No difference between groups was found in the body weight. Handled animals showed a reduction in the total kidney wet weight, water intake, urinary volume, CC, plasma angiotensin II, corticosterone and aldosterone when compared to the nonhandled and an increase in the urinary osmolality and sodium excretion fraction. No differences in serum potassium and no evidence of structural changes were demonstrated by histological analysis. CONCLUSION: Neonatal handling induced long-lasting effects decreasing renal function without evidence of kidney structural changes.

Social instigation and aggressive behavior in mice: role of 5-HT1A and 5-HT1B receptors in the prefrontal cortex.

RATIONALE: Social instigation is used in rodents to induce high levels of aggression, a pattern of behavior with certain parallels to that of violent individuals. This procedure consists of a brief exposure to a provocative stimulus male, before direct confrontation with an intruder. Studies using 5-HT1A and 5-HT1B receptor agonists show an effective reduction in aggressive behavior. An important site of action for these drugs is the ventral orbitofrontal cortex (VO PFC), an area of the brain which is particularly relevant in the inhibitory control of aggressive and impulsive behavior. OBJECTIVES: The objectives of the study are to assess the anti-aggressive effects of 5-HT1A and 5-HT1B agonist receptors [8-hydroxy-2-(di-n-propylamino) tetralin hydrobromide (8-OH-DPAT) and CP-93,129] in the VO PFC of socially provoked male mice. To confirm the specificity of the receptor, 5-HT1A and 5-HT1B antagonist receptors (WAY-100,635 and SB-224,289) were microinjected into the same area, in order to reverse the agonist effects. RESULTS: 8-OH-DPAT (0.56 and 1.0 microg) reduced the frequency of attack bites. The lowest dose of CP-93,129 (0.1 microg) also decreased the number of attack bites and lateral threats. 5-HT1A and 5-HT1B receptor agonists differed in their effects on non-aggressive activities, the former decreasing rearing and grooming, and the latter, increasing these acts. Specific participation of the 1A and 1B receptors was verified by reversal of anti-aggressive effects using selective antagonists WAY-100,635 (10.0 microg) and SB-224,289 (1.0 microg). CONCLUSIONS: The decrease in aggressiveness observed with microinjections of 5-HT1A and 5-HT1B receptor agonists into the VO PFC of socially provoked mice, supports the hypothesis that activation of these receptors modulates high levels of aggression in a behaviorally specific manner.

Effects of neonatal handling on central noradrenergic and nitric oxidergic systems and reproductive parameters in female rats.

Early-life environmental events that disrupt the mother-pup relationship may induce profound long-lasting changes on several behavioral and neuroendocrine systems. The neonatal handling procedure, which involves repeated brief maternal separations followed by experimental manipulations, reduces sexual behavior and induces anovulatory estrous cycles in female rats. On the afternoon of proestrus, neonatally handled females show a reduced surge of luteinizing hormone (LH) and an increased content of gonadotropin-releasing hormone in the medial preoptic area (MPOA). In order to detect the possible causes for the reduced ovulation and sexual behavior, the present study aimed to analyze the effects of neonatal handling on noradrenaline (NA) and nitric oxide (NO) levels in the MPOA on the afternoon of proestrus. Neonatal handling reduced MHPG (NA metabolite) levels and MHPG/NA ratio in the MPOA, indicating decreased NAergic activity. Additionally, neonatal handling decreased NO levels, as measured by the metabolites (NO(x)), nitrite and nitrate in the same period. We may conclude that the neonatal handling procedure decreased activity of the NAergic and NOergic systems in the MPOA during proestrus, which is involved in the control of LH and FSH secretion, and this may possibly explain the anovulatory estrous cycles and reduced sexual behavior of the neonatally handled female rats.

Postnatal development of inhibitory synaptic transmission in the anterior piriform cortex.

The morphological and functional development of inhibitory circuit in the anterior piriform cortex (aPC) during the first three postnatal weeks may be crucial for the development of odor preference learning in infant rodents. As first step toward testing this hypothesis, we examined the normal development of GABAergic synaptic transmission in the aPC of rat pups during the postnatal days (P) 5-8 and 14-17. Whole cell patch-clamp recordings of layer 2/3 (L2/3) aPC pyramidal cells revealed a significant increase in spontaneous (sIPSC) and miniature (mIPSC) inhibitory postsynaptic current frequencies and a decrease in mIPSC rise and decay-time constant at P14-P17. Moreover, as the development of neocortical inhibitory circuit can be driven by sensory experience, we recorded sIPSC and mIPSC onto L2/3 aPC pyramidal cells from unilateral naris-occluded animals. Early partial olfactory deprivation caused by naris occlusion do not affected the course of age-dependent increase IPSC frequency onto L2/3 aPC pyramidal cell. However, this age-dependent increase of sIPSC and mIPSC frequencies were lower on aPC pyramidal cells ipsilateral to the occlusion side. In addition, the age-dependent increase in sIPSC frequency and amplitude were more pronounced on aPC pyramidal cells contralateral to the occlusion. While mIPSC kinetics were not affected by age or olfactory deprivation, at P5-P8, the sIPSC decay-time constant on aPC pyramidal cells of both hemispheres of naris-occluded animals were significantly higher when compared to sham. These results demonstrated that the GABAergic synaptic transmission on the aPC changed during postnatal development by increasing inhibitory inputs on L2/3 pyramidal cells, with increment in frequency of both sIPSC and mIPSC and faster kinetics of mIPSC. Our data suggested that the maturation of GABAergic synaptic transmission was little affected by early partial olfactory deprivation. These results could contribute to unravel the mechanisms underlying the development of odor processing and olfactory preference learning.

Effects of renovascular hypertension on reproductive function in male rats.

OBJECTIVE: The present study investigated the effects of renovascular hypertension (2K/1C model) on the reproductive function of male rats, represented by sexual behavior, plasma prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone, and spermatogenesis. METHODS: The present experiments were performed to investigate the reproductive function of 2K/1C male Wistar rats and compare with 2K/1C male rats successfully treated for hypertension with nifedipine and was divided in the following groups: (1) Sham+V (n=10): Sham-operated males with vehicle used; (2) Sham+N (n=13): Sham-operated males treated with nifedipine (10 mg/kg/day); (3) 2K/1C+V (n=14): 2K/1C-operated males with vehicle used; and (4) 2K/1C+N (n=16): 2K/1C-operated males treated with nifedipine. RESULTS: The data indicated an association between hypertension induced by the 2K/1C model and reduction of reproductive function, as demonstrated by an impairment of sexual behavior, higher plasma PRL and lower plasma testosterone and FSH. The treatment with nifedipine prevented the reduction of sexual behavior and the increase of plasma PRL, but did not alter the reduction of plasma testosterone and FSH and spermatogenesis of 2K/1C rats. CONCLUSIONS: Reproductive function is adversely affected in the 2K/1C animal model, and high blood pressure plays a role in the modulation of plasma PRL and sexual behavior. Moreover, other events, without high blood pressure, but with high plasma renin activity associated with the 2K/1C model, contribute directly to the reduction of plasma testosterone and FSH and impaired spermatogenesis.

Effects of acute stress on the day of proestrus on sexual behavior and ovulation in female rats: participation of the angiotensinergic system.

Physical or emotional stress can affect the female reproductive physiology and angiotensin II (Ang II) is a hormone that participates in the stress response and also in the control of reproductive hormones. The present study aimed at evaluating the effects of acute stress in the morning and afternoon of proestrus on sexual behavior and ovulation and the participation of Ang II in the stress-induced effects. Female rats with regular estrous cycles were used. Several different stress protocols were tested in the morning and in the afternoon of proestrus: restraint stress 10 min; restraint stress 1 h and ether stress, respectively. The participation of Ang II was evaluated by injecting Ang II receptor antagonists (losartan and PD123319) 15 min before stress. The lordosis quotient was recorded and the number of oocytes was counted. Plasma levels of luteinizing hormone, progesterone, prolactin and corticosterone were measured. All types of stress in the morning of proestrus induced a reduction in the number of oocytes. Restraint stress (1 h) in the afternoon of proestrus induced a significant reduction in the lordosis quotient. Peripheral and central losartan, but not PD123319, injections partly reverted the effects of stress on ovulation in the morning of proestrus. Acute stress in the morning of proestrus also reduced luteinizing hormone, progesterone and prolactin surges later on the same day. In conclusion, acute stress on the day of proestrus can affect female reproductive physiology. Moreover, the angiotensinergic system, through AT(1) receptors, participates in the effects of acute stress in the morning of proestrus.

Intervention with the mother-infant relationship reduces cell proliferation in the Locus Coeruleus of female rat pups.

The Locus Coeruleus (LC) is a noradrenergic nucleus involved in several neuroendocrine and behavioral functions. During the neonatal period, the LC is critical for olfactory learning. Full development occurs during the early postnatal period. Environmental interventions after birth may affect neurogenesis. In rats, the neonatal handling procedure has been used as a model to analyze the effects of environmental intervention early in life. It has been related to several long-lasting behavioral and neuroendocrine changes. The present study analyzed the effects of handling on the number of neurons, cellular proliferation, and apoptosis in the LC of 11-day-old female rats. Wistar rat pups were submitted to brief maternal separation followed by handling (1 min per day from postnatal day [PND] 1 to 10). On PND 11, the LC was analyzed using immunohistochemistry for NeuN and BrdU, TUNEL staining, and electron microscopy. The intervention reduced the number of neurons in the LC but showed no significant change in the number of apoptotic cells, as measured by the TUNEL technique. However, the number of proliferating cells was significantly lower in the handled rat pups as compared with the nonhandled ones. This study demonstrates that the infant LC is sensitive to changes in maternal behavior. A seemingly mild environmental intervention during the neonatal period may reprogram the development of the LC, altering cell proliferation. (PsycINFO Database Record

Satiety assessment in neonatally handled rats.

We have previously demonstrated that neonatal handling increases sweet food ingestion. In the present study, we examined whether food intake, using different kinds of food, is altered in neonatally handled animals, with or without inducing satiety using a sucrose solution. Abdominal fat, glycemia and hormones linked to appetite including leptin, ghrelin and insulin were also measured. We tested palatable food consumption in the homecage to verify whether environmental cues could influence ingestion. Nests of Wistar rats were either (1) non-handled or (2) handled (10 min/day). Handling was performed on days 1-10 after birth. When adults, rats were habituated to sweet food (Froot Loops, Kellogg's) and to palatable fiber pellets (Fiber One), Nestlé). Sweet food consumption was increased in the neonatally handled group, when tested in the homecage, and also in the satiety experiment. These rats displayed a satiety curve when compared to the control group, which ate less but constantly. Handled rats exposed to a sucrose solution decreased sweet food ingestion, which did not occur in the control group. When exposed to a food with complex carbohydrates, these differences disappeared. There were no differences in body weight, abdominal fat or in glycemia, as well as no differences in plasma levels of insulin or leptin. However, ghrelin was decreased in neonatally handled rats. Neonatally handled rats demonstrated an increased consumption of sweet food, satiety responses to sucrose, as well as decreased levels of plasma ghrelin. It is possible that signaling mechanisms related to satiety, both peripherally and/or centrally may contribute to these behavioral findings.

Neonatal handling reduces angiotensin II receptor density in the medial preoptic area and paraventricular nucleus but not in arcuate nucleus and locus coeruleus of female rats.

Neonatal handling alters the hypothalamic-pituitary-adrenal (HPA) axis and the hypothalamic-pituitary-gonads axis (HPG) in adult animals, and angiotensin II (Ang II) modulates the functions in these axes. We tested whether neonatal handling could change the density of Ang II receptors in some central areas in female rats. Results showed decreased density of the Ang II receptors in the medial preoptic area (MPOA) and hypothalamic paraventricular nucleus (PVN) of the neonatal handled group.

Estradiol and progesterone modulation of angiotensin II receptors in the arcuate nucleus of ovariectomized and lactating rats.

The expression of angiotensin II (Ang II) receptors in the brain is modulated by estradiol and progesterone. Considering that Ang II plays a critical role in controlling prolactin secretion and that neurons in the arcuate nucleus (ARC) are the main regulator of this function, the present study aimed to evaluate ARC Ang II receptor binding in 2 experimental models with different estradiol and progesterone plasma levels. Animals were divided into 4 groups: ovariectomy (OVX) plus oil vehicle, OVX plus estradiol and progesterone replacement, lactating rats on day 7 postpartum, and lactating rats on day 20. Animals were killed by decapitation, and the brains were removed. Ang II receptors were quantified by autoradiography in ARC. Trunk blood samples were collected, and plasma estradiol and progesterone were measured by radioimmunoassay. Treatment of OVX rats with estradiol and progesterone increased Ang II receptor binding when compared to OVX vehicle-treated animals. Plasma estradiol (r = +0.77) and progesterone (r = +0.87) were highly correlated with Ang II receptors in ovariectomized animals. Lactating rats (day 20) showed a significant decrease in Ang II receptor binding and plasma progesterone when compared to lactating rats (day 7), however, no difference was seen in plasma estradiol. Plasma levels of progesterone (r = +0.81), but not estradiol (r = +0.32), were highly correlated with Ang II receptors in lactating rats. In conclusion, present results show that ARC Ang II receptors decreases on day 20 of lactation compared to day 7 and are highly correlated with plasma progesterone, indicating a pivotal role for progesterone in this regulation.

Neonatal handling induces alteration in progesterone secretion after sexual behavior but not in angiotensin II receptor density in the medial amygdala: implications for reproductive success.

Neonatal handling affects the hypothalamus-pituitary-gonadal axis in female rats. Indeed, postnatal handling induces anovulatory estrous cycles and decreases sexual receptiveness. On the other hand, Angiotensin II (Ang II) infused into the medial amygdala (MeA) reduces sexual behavior in male and female rats. Considering this, and that gonadal steroid secretion after copulatory behavior is important for reproductive success, the purpose of the present study was to investigate whether the reduction in sexual receptiveness in neonatally handled female rats is mediated by changes in Ang II receptor density in MeA. Moreover, gonadal steroid secretion after sexual behavior was analyzed. Two groups of female Wistar rats were studied: nonhandled (pups were left undisturbed) and handled (pups were handled for 1 min once a day during the first 10 days of life). Once they were 80-85 days old in the evening of the proestrus day, sexual receptiveness was recorded and after that the animals were killed by decapitation. Trunk blood samples were collected, and plasma estradiol and progesterone were measured by radioimmunoassay. The brains were removed for Ang II receptor autoradiography in MeA. The decreased lordosis quotient in the neonatally handled group was confirmed in the present study. Neonatal handling also reduced the progesterone concentration in the plasma, but did not change the estradiol and the density of Ang II receptors in MeA. The reduced progesterone could be due to the decreased lordosis frequency of handled females. However, this decreased sexual receptiveness is not mediated by changes in Ang II receptors in MeA.

Effects of sleep restriction during pregnancy on the mother and fetuses in rats.

The present study aimed to analyze the effects of sleep restriction (SR) during pregnancy in rats. The following three groups were studied: home cage (HC pregnant females remained in their home cage), Sham (females were placed in tanks similar to the SR group but with sawdust) and SR (females were submitted to the multiple platform method for 20 h per day from gestational days (GD) 14 to 20). Plasma corticosterone after 6 days of SR was not different among the groups. However, the relative adrenal weight was higher in the SR group compared with the HC group, which suggests possible stress impact. SR during pregnancy reduces the body weight of the female but no changes in liver glycogen, cholesterol and triglycerides, and muscle glycogen were detected. On GD 20, the fetuses of the females submitted to SR exhibited increased brain derived neurotrophic factor (BDNF) in the hippocampus, which indicates that sleep restriction of mothers during the final week of gestation may affect neuronal growth factors in a fetal brain structure, in which active neurogenesis occurs during the deprivation period. However, no changes in the total reactive oxygen species (ROS) in the cortex, hippocampus, or cerebellum of the fetuses were detected. SR females showed no major change in the maternal behavior, and the pups' preference for the mother's odor on postpartum day (PPD) 7 was not altered. On GD 20, the SR females exhibited increased plasma prolactin (PRL) and oxytocin (OT) compared with the HC and Sham groups. The negative outcomes of sleep restriction during delivery could be related, in part, to this hormonal imbalance. Sleep restriction during pregnancy induces different changes compared with the changes described in males and affects both the mother and offspring.