Neonatal Anoxia Impacts Rats' Maternal Behavior and Offspring Development due to Ultrasonic Vocalization's Impairment.

Hypoxic-ischemic encephalopathy is a severe clinical condition, among others, affecting the brain after offspring exposure to neonatal anoxia, which causes persistent sensorimotor and cognitive deficits. During peripartum, maternal behaviors are crucial for the healthy development of the offspring. In rats, the vocalization of newborns, around 40 kHz, corresponds to separation calls that encourage their mothers to retrieve them. Alterations in this pattern affect the maternal behavior addressed to the offspring. This study aimed to evaluate the maternal behavior of primiparous rats whose offspring were exposed to neonatal anoxia in P2 (postpartum day) during the lactation period, to assess mother-pup interactions through the pups' vocalization from P3 to P18. It also intends to quantify eventual neuronal alterations in the mothers' medial preoptic area after the last weaning (P21) through FOS protein expression. Anoxia offspring were found to reduce maternal behaviors toward them, increased frequency of separation calls in the male anoxia group, and reduced vocalization rate in the female anoxia group compared to their respective controls. Body weight gain reduction of males' and females' anoxia was observed. We concluded that anoxia exerts deleterious effects on the vocalization patterns of the pups, with sex differences that alter maternal behavior toward them. Impaired USV makes an additional negative impact on the already noxious effects of neonatal anoxia. Understanding those phenomena applies/contributes to guiding procedures and strategies to mitigate the deleterious outcomes and orient research concerning the complexity of neonatal anoxia events and the influence of maternal care quality concerning the pups, which should also be considered sex differences.

Repeated Domperidone treatment modulates pulmonary cytokines in LPS-induced acute lung injury in mice.

The dopaminergic antagonist drug Domperidone has immunomodulatory effects. We investigated the effects of repeated Domperidone treatment in a model of Lypopolyssacharide (LPS)-induced acute lung inflammation. Adult C57BL/6J mice were treated with either Vehicle or Domperidone for 5days, and challenged intranasally with LPS in the following day. The behavior of mice was analyzed in the open field and elevated plus-maze test before and 24h after LPS challenge. The bronchoalveolar lavage fluid, blood and lung tissue were collected 24h and 48h after LPS challenge. Domperidone treatment increased LPS-induced tumor necrosis factor (TNF) and interleukin (IL)-6 production in the bronchoalveolar lavage fluid, without altering tissue damage and the number of immune cells in the lungs and circulation. Locomotor and anxiety-like behavior were unchanged after Domperidone and/or LPS treatment. Cytokine data indicate that Domperidone promotes a change in activity of other cell types, likely alveolar epithelial cells, without affecting immune cell migration in the present model. Due to the role of these cytokines in progression of inflammation, Domperidone treatment may exacerbate a subsequent inflammatory injury.

Acute Lipopolysaccharide Switches the Selection of Maternal Behavior to Predatory Behavior in Female Rats.

OBJECTIVES: A common problem during the postpartum period and during lactation is being affected by infection due to Gram-negative bacteria. In this situation, a sick mother needs to choose between caring for her pups or the need for survival. This study analyzed the effects of lipopolysaccharide (LPS)-induced sickness behavior on selection between maternal behavior (MB) and predatory behavior (PB) in lactating rats. To assess the LPS-induced sickness behavior, the plasma tumor necrosis factor-α (TNF-α) levels were measured. METHODS: Lactating rats received 100 µg/kg LPS or saline solution on day 5 or 6 of lactation, 2 h before testing. Five pups and 5 cockroaches were introduced to the experimental cage at the same time and maternal and PB were observed for 30 min. The MB was measured by the pup contact, grouping, grooming, and kyphosis and the PB by contacting, eating, and foraging insects. General maternal activity was also observed, including exploration, self-grooming, and immobility. Immediately after the observations, blood was collected to measure the plasma TNF-α levels. RESULTS: LPS administration reduced the time and frequency of pup contact, grouping, grooming, and kyphosis, with an increase in the latency to first pup contact and grouping. With regard to PB, the time of foraging and eating insects increased, and the latencies to first insect contact, eating insects, and foraging decreased. With regard to general maternal activity, immobility time and TNF-α levels increased in the LPS-treated group. CONCLUSIONS: LPS exposure switched MB to PB, prioritizing maternal survival. Thus, in more favorable situations, these rats may have new offspring and therefore her species would survive for long.

Central and peripheral oxytocin profiles during milking in ewes / Perfil de ocitocinea central e periférica em ovelhas lactantes

The present work investigated the possible relationship between central and peripheral oxytocin (OT) release during milking in experimental ewes. Ten multiparous ewes were divided into four groups according to milk ejection stimuli: exclusive machine milking (EM), mixed-management milking and suckling, lambs separated during the night and reunited with their mother after morning milking (MMS); mixed-management with manual milking (MMM), and exclusive suckling (ES) lambs also separated during the night. Simultaneous sampling of cerebrospinal fluid (CSF) and blood was performed during milking. The means, standard deviations, variation coefficients, and minimum and maximum CSF and plasma OT concentrations were the following, respectively: 257.88 ± 265.90 pg/ml, 103.11%, and 11.70 and 1000.00 pg/ml. No statistically significant correlations were found between OT concentrations in the CSF and plasma samples (EM: -0.26; ES: -0.19; MMM: 0.05; MMS: 0.04). The OT concentration in CSF was not influenced by milk ejection stimuli, although plasma OT was higher in the MMM (679.80 ± 25.63) and MMS (591.82 ± 30.56) groups compared with the EM and ES groups. Additionally, plasma OT concentrations were higher in the OME group (381.04 ± 22.09) compared with the AE group (218.82 ± 27.04). In conclusion, no positive correlations were found between central and peripheral OT concentrations during milking and suckling. Plasma OT concentrations differed as a function of milking management and had consequences for both milk ejection and production. Plasma but not CSF oxytocin concentrations were influenced by different milk ejection stimuli.(AU)

Foi investigada a possivel relação entre as concentrações de ocitocina no líquido cefalorraquidiano e no soro em diferentes formas de ordenha em ovinos. Foram utilizadas dez ovelhas multiparas, divididas em quatro grupos de acordo com o estímulo para ejeção do leite; ordenha exclusivamente mecânica (EM), ordenha mista mamada com os carneiros separados das mães durante a noite e reunidos a elas pela manhã para amamentação (MMS); ordenha mista com ordenha manual (MMS); apenas amamentação natural (ES). Foram coletadas amostras de fluído cerebroespinhal e de sangue, simultaneamente, durante as ordenhas. A média, o coeficiente de variação e os valores máximos e mínimos de ocitocina do plasma foram respectivamente 257,88 ± 265,90 pg/ml, 103,11%, e 11,70 e 1000,00 pg/ml. Não foram encontradas correlações entre as concentrações centrais e plasmáticas de ocitocina (EM: -0,26; ES: -0,19; MMM: 0,05; MMS: 0,04). Não foi evidenciada influência do tipo de estimulo para ejeção do leite nas concentrações centrais de ocitocina. Entretanto, as concentrações plasmaticas de ocitocina foram maiores nos grupos MMM (679,80 +- 25,63) e MMS (591,82 +- 30,56), quando comparadas às dos grupos EM e ES. Além disso, as concentrações plasmáticas de ocitocina foram maiores no grupo de OME (381,04+-22,09) em relação ao grupo AE (218,82 +-27,04). Os resultados obtidos sugerem que as concentrações plasmáticas de ocitocina são mais sensíveis ao tipo de ordenha que as concentrações centrais deste hormônio.(AU)

Central and peripheral oxytocin profiles during milking in ewes / Perfil de ocitocinea central e periférica em ovelhas lactantes

The present work investigated the possible relationship between central and peripheral oxytocin (OT) release during milking in experimental ewes. Ten multiparous ewes were divided into four groups according to milk ejection stimuli: exclusive machine milking (EM), mixed-management milking and suckling, lambs separated during the night and reunited with their mother after morning milking (MMS); mixed-management with manual milking (MMM), and exclusive suckling (ES) lambs also separated during the night. Simultaneous sampling of cerebrospinal fluid (CSF) and blood was performed during milking. The means, standard deviations, variation coefficients, and minimum and maximum CSF and plasma OT concentrations were the following, respectively: 257.88 ± 265.90 pg/ml, 103.11%, and 11.70 and 1000.00 pg/ml. No statistically significant correlations were found between OT concentrations in the CSF and plasma samples (EM: -0.26; ES: -0.19; MMM: 0.05; MMS: 0.04). The OT concentration in CSF was not influenced by milk ejection stimuli, although plasma OT was higher in the MMM (679.80 ± 25.63) and MMS (591.82 ± 30.56) groups compared with the EM and ES groups. Additionally, plasma OT concentrations were higher in the OME group (381.04 ± 22.09) compared with the AE group (218.82 ± 27.04). In conclusion, no positive correlations were found between central and peripheral OT concentrations during milking and suckling. Plasma OT concentrations differed as a function of milking management and had consequences for both milk ejection and production. Plasma but not CSF oxytocin concentrations were influenced by different milk ejection stimuli.

Foi investigada a possivel relação entre as concentrações de ocitocina no líquido cefalorraquidiano e no soro em diferentes formas de ordenha em ovinos. Foram utilizadas dez ovelhas multiparas, divididas em quatro grupos de acordo com o estímulo para ejeção do leite; ordenha exclusivamente mecânica (EM), ordenha mista mamada com os carneiros separados das mães durante a noite e reunidos a elas pela manhã para amamentação (MMS); ordenha mista com ordenha manual (MMS); apenas amamentação natural (ES). Foram coletadas amostras de fluído cerebroespinhal e de sangue, simultaneamente, durante as ordenhas. A média, o coeficiente de variação e os valores máximos e mínimos de ocitocina do plasma foram respectivamente 257,88 ± 265,90 pg/ml, 103,11%, e 11,70 e 1000,00 pg/ml. Não foram encontradas correlações entre as concentrações centrais e plasmáticas de ocitocina (EM: -0,26; ES: -0,19; MMM: 0,05; MMS: 0,04). Não foi evidenciada influência do tipo de estimulo para ejeção do leite nas concentrações centrais de ocitocina. Entretanto, as concentrações plasmaticas de ocitocina foram maiores nos grupos MMM (679,80 +- 25,63) e MMS (591,82 +- 30,56), quando comparadas às dos grupos EM e ES. Além disso, as concentrações plasmáticas de ocitocina foram maiores no grupo de OME (381,04+-22,09) em relação ao grupo AE (218,82 +-27,04). Os resultados obtidos sugerem que as concentrações plasmáticas de ocitocina são mais sensíveis ao tipo de ordenha que as concentrações centrais deste hormônio.

Cholecystokinin modulation of maternal behavior

Maternal behavior is regulated by several neurotransmitters, neuropeptides, and hormones. This mini-review focuses on the role of cholecystokinin (CCK), a neuropeptide and gut hormone best known as a satiety signal, in mediating maternal behavior. In addition to the role of CCK in the infant in mother-infant interactions, maternal CCK appears to also be important. We discuss maternal behavior research, mainly in rats, that has examined the effect of administering CCK to dams, CCK-opioid interactions, and maternal behavior in rats that lack CCK1 receptors. We discuss the possibility that CCK might play a role in neurological adjustments during pregnancy that ultimately influence behavioral adaptations by the offspring during lactation. Finally, we hypothesize that maternal CCK is also involved in maternal memory and reward...

The role of prolactin in prostatic inflammation / O papel da prolactina na inflamação prostática

Several reports have shown that prolactin (PRL) plays a role in prostatic growth, but few studies considered the role of PRL in the process of prostatic inflammation. Young (45 ± 5 days old) and adult (75 ± 5 days old) male Wistar rats were subcutaneously injected daily with domperidone (4.0 mg.kg-1) to maintain high serum PRL levels. The animals were treated for 15, 30, 45 or 60 days. Blood and prostate samples were collected at the end of each treatment for PRL dosage and histological analysis, respectively. Only young animals treated with DOMP for 15 and 30 days displayed inflammatory infiltrate in the prostate. These results confirm literature data in regards to PRL involvement in inducing prostate inflammation. Moreover, it was concluded that young animals are more susceptible then adults to the PRL action concerning prostate inflammation(AU)

A prolactina (PRL) influencia o crescimento prostático, entretanto poucos estudos investigaram o papel da PRL na inflamação prostática. Ratos Wistar jovens (45 ± 5 dias de idade) e adultos (75 ± 5 dias de idade) receberam injeções subcutâneas diárias de domperidona (4,0 mg.kg-1) para manter níveis séricos altos de PRL. Os animais foram tratados por 15, 30, 45 ou 60 dias. Amostras de sangue e próstata foram coletadas ao final dos tratamentos para dosagem de PRL e análise histológica, respectivamente. Apenas os animais jovens tratados com domperidona por 15 e 30 dias apresentaram infiltrado inflamatório na próstata. Esses resultados confirmaram a participação da PRL na indução da inflamação prostática. A conclusão obtida foi que animais jovens são mais susceptíveis à ação da PRL na inflamação da próstata que os adultos(AU)

Cholecystokinin modulation of maternal behavior

Maternal behavior is regulated by several neurotransmitters, neuropeptides, and hormones. This mini-review focuses on the role of cholecystokinin (CCK), a neuropeptide and gut hormone best known as a satiety signal, in mediating maternal behavior. In addition to the role of CCK in the infant in mother-infant interactions, maternal CCK appears to also be important. We discuss maternal behavior research, mainly in rats, that has examined the effect of administering CCK to dams, CCK-opioid interactions, and maternal behavior in rats that lack CCK1 receptors. We discuss the possibility that CCK might play a role in neurological adjustments during pregnancy that ultimately influence behavioral adaptations by the offspring during lactation. Finally, we hypothesize that maternal CCK is also involved in maternal memory and reward.(AU)

The role of prolactin in prostatic inflammation / O papel da prolactina na inflamação prostática

Several reports have shown that prolactin (PRL) plays a role in prostatic growth, but few studies considered the role of PRL in the process of prostatic inflammation. Young (45 ± 5 days old) and adult (75 ± 5 days old) male Wistar rats were subcutaneously injected daily with domperidone (4.0 mg.kg-1) to maintain high serum PRL levels. The animals were treated for 15, 30, 45 or 60 days. Blood and prostate samples were collected at the end of each treatment for PRL dosage and histological analysis, respectively. Only young animals treated with DOMP for 15 and 30 days displayed inflammatory infiltrate in the prostate. These results confirm literature data in regards to PRL involvement in inducing prostate inflammation. Moreover, it was concluded that young animals are more susceptible then adults to the PRL action concerning prostate inflammation...

A prolactina (PRL) influencia o crescimento prostático, entretanto poucos estudos investigaram o papel da PRL na inflamação prostática. Ratos Wistar jovens (45 ± 5 dias de idade) e adultos (75 ± 5 dias de idade) receberam injeções subcutâneas diárias de domperidona (4,0 mg.kg-1) para manter níveis séricos altos de PRL. Os animais foram tratados por 15, 30, 45 ou 60 dias. Amostras de sangue e próstata foram coletadas ao final dos tratamentos para dosagem de PRL e análise histológica, respectivamente. Apenas os animais jovens tratados com domperidona por 15 e 30 dias apresentaram infiltrado inflamatório na próstata. Esses resultados confirmaram a participação da PRL na indução da inflamação prostática. A conclusão obtida foi que animais jovens são mais susceptíveis à ação da PRL na inflamação da próstata que os adultos...

Dynamics of mother-pup interactions: tradeoff between environment and physiology

The emergence and maintenance of maternal behavior are under the influence of environmental cues such as light and dark periods. This article discusses the characteristic neurobiology of the behavioral patterns of lactating rats. Specifically, the hormonal basis and neurocircuits that determine whether mother rats show typical sequential patterns of behavioral responses are discussed. During lactation, rats express a sequential pattern of behavioral parameters that may be determined by hormonal variations. Sensorial signals emitted by pups, as well as environmental cues, are suggested to serve as conditioned stimuli for these animals. Finally, the expression of maternal behavior is discussed under neuroeconomic and evolutionary perspectives.

Post-partum testosterone administration partially reverses the effects of perinatal cadmium exposure on sexual behavior in rats

This study investigated the effects of perinatal cadmium exposure on sexual behavior, organ weight, and testosterone levels in adult rats. We examined whether immediate postpartum testosterone administration is able to reverse the toxic effects of the metal. Forty pregnant Wistar rats were divided into three groups: 1) control, 2) 10 mg kg-1 cadmium chloride per day, and 3) 20 mg kg-1 cadmium chloride per day. These dams were treated on gestational days 18 and 21 and from lactation 1 to 7. Immediately after birth, half of the offspring from the experimental and control groups received 50 μl (i.p.) of 0.2% testosterone. Male sexual behavior, histological analysis and weight of organs as well as serum testosterone levels were assessed. Results showed that both cadmium doses disrupted sexual behavior in male rats, and postnatal treatment with testosterone reversed the toxic effects of 10 mg kg-1 cadmium and attenuated the effects of 20 mg kg-1 cadmium. Body weight and absolute testis, epididymis, and seminal vesicle weight were decreased by the higher cadmium dose, and testosterone supplementation did not reverse these effects. Serum testosterone levels were unaffected by both cadmium doses. No histological changes were detected in all organs analyzed. Maternal cadmium exposure effects in sexual parameters of male rat offspring were explained by the altered masculinization of the hypothalamus. We suggest that cadmium damaged cerebral sexual differentiation by its actions as an endocrine disruptor and supported by the changes discretely observed from early life during sexual development to adult life, reflected by sexual behavior. Testosterone supplementation after birth reversed some crucial parameters directly related to sexual behavior.

Post-partum testosterone administration partially reverses the effects of perinatal cadmium exposure on sexual behavior in rats

This study investigated the effects of perinatal cadmium exposure on sexual behavior, organ weight, and testosterone levels in adult rats. We examined whether immediate postpartum testosterone administration is able to reverse the toxic effects of the metal. Forty pregnant Wistar rats were divided into three groups: 1) control, 2) 10 mg kg-1 cadmium chloride per day, and 3) 20 mg kg-1 cadmium chloride per day. These dams were treated on gestational days 18 and 21 and from lactation 1 to 7. Immediately after birth, half of the offspring from the experimental and control groups received 50 μl (i.p.) of 0.2% testosterone. Male sexual behavior, histological analysis and weight of organs as well as serum testosterone levels were assessed. Results showed that both cadmium doses disrupted sexual behavior in male rats, and postnatal treatment with testosterone reversed the toxic effects of 10 mg kg-1 cadmium and attenuated the effects of 20 mg kg-1 cadmium. Body weight and absolute testis, epididymis, and seminal vesicle weight were decreased by the higher cadmium dose, and testosterone supplementation did not reverse these effects. Serum testosterone levels were unaffected by both cadmium doses. No histological changes were detected in all organs analyzed. Maternal cadmium exposure effects in sexual parameters of male rat offspring were explained by the altered masculinization of the hypothalamus. We suggest that cadmium damaged cerebral sexual differentiation by its actions as an endocrine disruptor and supported by the changes discretely observed from early life during sexual development to adult life, reflected by sexual behavior. Testosterone supplementation after birth reversed some crucial parameters directly related to sexual behavior.(AU)

Dynamics of mother-pup interactions: tradeoff between environment and physiology

The emergence and maintenance of maternal behavior are under the influence of environmental cues such as light and dark periods. This article discusses the characteristic neurobiology of the behavioral patterns of lactating rats. Specifically, the hormonal basis and neurocircuits that determine whether mother rats show typical sequential patterns of behavioral responses are discussed. During lactation, rats express a sequential pattern of behavioral parameters that may be determined by hormonal variations. Sensorial signals emitted by pups, as well as environmental cues, are suggested to serve as conditioned stimuli for these animals. Finally, the expression of maternal behavior is discussed under neuroeconomic and evolutionary perspectives.(AU)

Impact of maternal mild hyperglycemia on maternal care and offspring development and behavior of Wistar rats.

The aim of the present study was to evaluate the effect of maternal mild hyperglycemia on maternal behavior, as well as the development, behavior, reproductive function, and glucose tolerance of the offspring. At birth, litters were assigned either to Control (subcutaneous (sc)-citrate buffer) or STZ groups (streptozotocin (STZ)-100mg/kg-sc.). On PND 90 both STZ-treated and Control female rats were mated. Glucose tolerance tests (GTT) and insulin tolerance tests (ITT) were performed during pregnancy. Pregnancy duration, litter size and sex ratio were assessed. Newborns were classified according to birth weight as small (SPA), adequate (APA), or large for pregnancy age (LPA). Maternal behavior was analyzed on PND 5 and 10. Offspring body weight, length, and anogenital distance were measured and general activity was assessed in the open field. Sexual behavior was tested in both male and female offspring. Levels of reproductive hormones and estrous cycle duration were evaluated in female offspring. Female offspring were mated and both a GTT and ITT performed during pregnancy. Neonatal STZ administration caused mild hyperglycemia during pregnancy and changed some aspects of maternal care. The hyperglycemic intrauterine milieu impaired physical development and increased immobility in the open field in the offspring although the latter effect appeared at different ages for males (adulthood) and females (infancy). There was no impairment in the sexual behavior of either male or female offspring. As adults, female offspring of STZ-treated mothers did not show glucose intolerance during pregnancy. Thus, offspring of female rats that show mild hyperglycemia in pregnancy have fewer behavioral and developmental impairments than previously reported in the offspring of severely diabetic dams suggesting that the degree of impairment is directly related to the mother glycemic intensity.

The periaqueductal gray as a critical site to mediate reward seeking during predatory hunting.

Previous studies using morphine-treated dams reported a role for the rostral lateral periaqueductal gray (rlPAG) in the behavioral switching between nursing and insect hunting, likely to depend on an enhanced seeking response to the presence of an appetitive rewarding cue (i.e., the roach). To elucidate the neural mechanisms mediating such responses, in the present study, we first observed how the rlPAG influences predatory hunting in male rats. Our behavioral observations indicated that bilateral rlPAG NMDA lesions dramatically interfere with prey hunting, leaving the animal without chasing or attacking the prey, but do not seem to affect the general levels of arousal, locomotor activity and regular feeding. Next, using Phaseolus vulgaris-leucoagglutinin (PHA-L), we have reviewed the rlPAG connection pattern, and pointed out a particularly dense projection to the hypothalamic orexinergic cell group. Double labeled PHA-L and orexin sections showed an extensive overlap between PHA-L labeled fibers and orexin cells, revealing that both the medial/perifornical and lateral hypothalamic orexinergic cell groups receive a substantial innervation from the rlPAG. We have further observed that both the medial/perifornical and lateral hypothalamic orexinergic cell groups up-regulate Fos expression during prey hunting, and that rlPAG lesions blunted this Fos increase only in the lateral hypothalamic, but not in the medial/perifornical, orexinergic group, a finding supposedly associated with the lack of motivational drive to actively pursue the prey. Overall, the present results suggest that the rlPAG should exert a critical influence on reward seeking by activating the lateral hypothalamic orexinergic cell group.

Open field behavior and intra-nucleus accumbens dopamine release in vivo in virgin and lactating rats

In adult female mammals, reproductive experience (e.g., mating, pregnancy, parturition, and lactation) has long-term behavioral, endocrine, and neurochemical implications. This experience causes behavioral and neurochemical changes that involve several brain areas important for the expression of maternal behavior. The present study showed that lactating rats exhibited reduced general locomotor activity in the open field test compared with virgin animals. Our hypothesis was that nucleus accumbens dopamine, which regulates maternal behavior in lactating rats, is also involved in the low expression of maternal locomotion in the open field test observed during the early stages of lactation and reflects decreased motivation. Initially we compared open field behavior in virgin and lactating rats to confirm our previous data. Thus, the in vivo release of dopamine in the nucleus accumbens in virgin and lactating female rats was measured. Perfusate concentrations of extracellular dopamine and its metabolites showed no differences between virgin and lactating rats. Thus, the reduced general activity observed in lactating rats might not be related to intra-nucleus accumbens dopamine control.(AU)

Open field behavior and intra-nucleus accumbens dopamine release in vivo in virgin and lactating rats

In adult female mammals, reproductive experience (e.g., mating, pregnancy, parturition, and lactation) has long-term behavioral, endocrine, and neurochemical implications. This experience causes behavioral and neurochemical changes that involve several brain areas important for the expression of maternal behavior. The present study showed that lactating rats exhibited reduced general locomotor activity in the open field test compared with virgin animals. Our hypothesis was that nucleus accumbens dopamine, which regulates maternal behavior in lactating rats, is also involved in the low expression of maternal locomotion in the open field test observed during the early stages of lactation and reflects decreased motivation. Initially we compared open field behavior in virgin and lactating rats to confirm our previous data. Thus, the in vivo release of dopamine in the nucleus accumbens in virgin and lactating female rats was measured. Perfusate concentrations of extracellular dopamine and its metabolites showed no differences between virgin and lactating rats. Thus, the reduced general activity observed in lactating rats might not be related to intra-nucleus accumbens dopamine control.

Modulation of post-coital dopaminergic tone by prior parity

The aim of this study was to investigate the possible effects of reproductive experience on dopaminergic profile in three different brain tissues, hypothalamus, striatum and cortex in rats on 7th-8th day of pregnancy during the light-dark shift (between 1700-1900h). Results showed that in hypothalamus, dopamine levels increased and DOPAC/DA decreased as a function of parity. In cortex, no differences were observed. In striata, the haloperidol-induced HVA and HVA/DA increases were less intense in experienced animals. These findings suggested that reproductive experience produced functional central changes during pregnancy, with different neurochemical responses depending on the brain region.

A dopamina age nos níveis endócrino, neuroquímico e comportamental. A experiência reprodutiva modula alguns destes aspectos: a dopamina está aumentada no estriato e no hipotálamo de ratas muiltigrávidas entre 12:00-14:00 horas. A sensibilidade dos terminais dopaminérgicos também parece ser modulada por uma experiência reprodutiva prévia. Nosso objetivo foi o de investigar os possíveis efeitos da experiência reprodutiva no perfil dopaminérgico de três diferentes tecidos cerebrais, hipotálamo, estriato e córtex em ratas no 7º-8º dia de gestação durante a fase de virada do ciclo claro-escuro (entre 17:00-19:00h). Nossos resultados mostraram que os níveis dopaminérgicos no hipotálamo aumentaram e o índice DOPAC/DA diminuiu em multigrávidas quando comparadas às primigrávidas. No córtex, nenhuma diferença foi encontrada. No estriato, o aumento de HVA e HVA/DA induzidos pelo haloperidol foi menos intenso nos animais experientes. Nossos resultados sugerem que a experiência reprodutiva produz alterações funcionais centrais durante a gestação, com diferentes respostas neuroquímicas de acordo com a região cerebral.

The periaqueductal gray and its potential role in maternal behavior inhibition in response to predatory threats.

Animals faced with conflicting cues, such as predatory threat and a given rewarding stimulus, must make rapid decisions to engage in defensive versus other appetitive behaviors. The brain mechanisms mediating such responses are poorly understood. However, the periaqueductal gray (PAG) seems particularly suitable for accomplishing this task. The PAG is thought to have, at least, two distinct general roles on the organization of motivated responses, i.e., one on the execution of defensive and reproductive behaviors, and the other on the motivational drive underlying adaptive responses. We have presently examined how the PAG would be involved in mediating the behavioral choice between mutually incompatible behaviors, such as reproduction or defense, when dams are exposed to pups and cat odor. First, we established the behavioral protocol and observed that lactating rats, simultaneously exposed to pups and cat odor, inhibited maternal behavior and expressed clear defensive responses. We have further revealed that cat odor exposure up-regulated Fos expression in the dorsal PAG, and that NMDA cytotoxic lesions therein were able to restore maternal responses, and, at the same time, block defensive responsiveness to cat odor. Potential paths mediating the dorsal PAG influences on the inhibition of appetitive (i.e., retrieving behavior) and consummatory (i.e., nursing) maternal responses are discussed. Overall, we were able to confirm the dual role of the PAG, where, in the present case, the dorsal PAG, apart from organizing defensive responses, also appears to account for the behavioral inhibition of non-defensive responses.

Afferent connections to the rostrolateral part of the periaqueductal gray: a critical region influencing the motivation drive to hunt and forage.

Previous studies have shown that a particular site in the periaqueductal gray (PAG), the rostrolateral PAG, influences the motivation drive to forage or hunt. To have a deeper understanding on the putative paths involved in the decision-making process between foraging, hunting, and other behavioral responses, in the present investigation, we carried out a systematic analysis of the neural inputs to the rostrolateral PAG (rlPAG), using Fluorogold as a retrograde tracer. According to the present findings, the rlPAG appears to be importantly driven by medial prefrontal cortical areas involved in controlling attention-related and decision-making processes. Moreover, the rlPAG also receives a wealth of information from different amygdalar, hypothalamic, and brainstem sites related to feeding, drinking, or hunting behavioral responses. Therefore, this unique combination of afferent connections puts the rlPAG in a privileged position to influence the motivation drive to choose whether hunting and foraging would be the most appropriate adaptive responses.