Biomedical subjects

Jodi L Pawluski

Publications and source records attributed to Jodi L Pawluski.

6 recordsLinked to original sources

PubMed2006

First reproductive experience persistently affects spatial reference and working memory in the mother and these effects are not due to pregnancy or 'mothering' alone.

Pregnancy and motherhood are life-altering events that result in a number of hormonal, neural and behavioral changes in the mother. Motherhood has been shown to influence spatial learning and memory performance of the mother. In turn new research has shown that reproductive experience (number of times pregnant and mothered) plays a significant role on spatial learning and memory performance. How long these changes persist after weaning and the role of pregnancy and/or mothering on these changes have yet to be fully investigated. The present study aimed to determine whether enhanced spatial working and/or reference memory in the mother is evident long after weaning and whether these effects are due, in part, to pregnancy or 'mothering' alone. Five groups of age-matched rats: multiparous, primiparous, nulliparous, pregnant-only and sensitized rats were tested approximately 1 month after weaning/pup-exposure, or 55 days after birth, on the spatial working/reference version of the radial arm maze. Results show that regardless of error type (reference or working memory errors), primiparous rats make fewer errors compared to multi- and nulli-parous rats, with a trend to enhanced memory compared to sensitized rats. In addition, pregnant-only rats completed the task on significantly fewer days than primiparous, multiparous, nulliparous and sensitized rats. Clearly the combination of first pregnancy and first mothering experience has a significant impact on hippocampus-dependent learning and memory performance in the mother.

Analysis of Variance↗

PubMed2006

High post-partum levels of corticosterone given to dams influence postnatal hippocampal cell proliferation and behavior of offspring: A model of post-partum stress and possible depression.

Post-partum stress and depression (PPD) have a significant effect on child development and behavior. Depression is associated with hypercortisolism in humans, and the fluctuating levels of hormones, including corticosterone, during pregnancy and the post-partum, may contribute to PPD. The present study was developed to investigate the effects of high-level corticosterone (CORT) post-partum in the mother on postnatal neurogenesis and behavior in the offspring. Sprague-Dawley dams were treated with either CORT (40 mg/kg) or sesame oil injections daily for 26 days beginning the day after giving birth. Dams were tested in the forced swim test (FST) and in the open field test (OFT) on days 24-26 post-partum. Results showed that the dams exposed to CORT expressed "depressive-like" behavior compared to controls, with decreased struggling behavior and increased immobility in the FST. To investigate the effects of treatment on hippocampal postnatal cell proliferation and survival in the offspring, males and females from treated dams were injected with BrdU (50 mg/kg) on postnatal day 21 and perfused either 24 h (cell proliferation) or 21 days (cell survival) later. Furthermore, male and female offspring from each litter were tested in adulthood on various behavioral tests, including the forced swim test, open field test, resistance to capture test and elevated plus maze. Intriguingly, male, but not female, offspring of CORT-treated dams exhibited decreased postnatal cell proliferation in the dentate gyrus. Both male and female offspring of CORT-treated dams showed higher resistance to capture and greater locomotor activity as assessed in the open field test. As high levels of CORT may be a characteristic of stress and/or depression, these findings support a model of 'CORT-induced' post-partum stress and possibly depression and demonstrate that the offspring of affected dams can exhibit changes in postnatal neurogenesis and behavior in adulthood.

Age Factors↗

PubMed2006

Gonadal hormone modulation of hippocampal neurogenesis in the adult.

Gonadal hormones modulate neurogenesis in the dentate gyrus (DG) of adult rodents in complex ways. Estradiol, the most potent estrogen, initially enhances and subsequently suppresses cell proliferation in the dentate gryus of adult female rodents. Much less is known about how estradiol modulates neurogenesis in the adult male rodent; however, recent evidence suggests that estradiol may have a moderate effect on cell proliferation but enhances cell survival in the DG of newly synthesized cells but only when estradiol is administered during a specific stage in the cell maturation cycle in the adult male rodent. Testosterone likely plays a role in adult neurogenesis, although there have been no direct studies to address this. However, pilot studies from our laboratory suggest that testosterone up-regulates cell survival but not cell proliferation in the DG of adult male rats. Progesterone appears to attenuate the estradiol-induced enhancement of cell proliferation. Neurosteroids such as allopregnalone decrease neurogenesis in adult rodents, while pregnancy and motherhood differentially regulate adult neurogenesis in the adult female rodent. Very few studies have investigated the effects of gonadal hormones on male rodents; however, studies have indicated that there is a gender difference in the response to hormone-regulated hippocampal neurogenesis in the adult. Clearly, more work needs to be done to elucidate the effects of gonadal hormones on neurogenesis in the DG of both male and female rodents.

Animals↗

PubMed2006

Hippocampal morphology is differentially affected by reproductive experience in the mother.

Pregnancy and mothering result in a number of hormonal, neurological, and behavioral changes that are necessary to ensure reproductive success. With subsequent reproductive experience (multiparity and mothering), further neurological and behavioral changes may result. Recent research has shown that previous motherhood enhances both hippocampus-dependent learning and memory and long-term potentiation (LTP); together with decreases in hippocampus volumes during pregnancy it is suggested that the hippocampus is affected by pregnancy and/or mothering. The present experiment aimed to investigate the effect of reproductive experience (nulli, primi-, and multiparity and mothering) on dendritic morphology in the CA1 and CA3 regions of the hippocampus. Brains were stained with a modified version of the single-section Golgi impregnation technique, and dendritic length, number of branch points, and spine density was analyzed for apical and basal regions of CA1 and CA3 pyramidal neurons. Primiparity and/or mothering resulted in dendritic remodeling in both the CA1 and CA3 hippocampal regions, and multiparity resulted in enhanced spine density in the basal CA1 region, which was positively correlated with number of male pups in a litter. These findings point to the effect of reproductive experience and offspring on plasticity in the hippocampus, an area not traditionally associated with motherhood.

Analysis of Variance↗

PubMed2005

Reproductive experience differentially affects spatial reference and working memory performance in the mother.

The transition to motherhood results in a number of hormonal, neurological, and behavioral changes necessary to ensure offspring survival. Once motherhood is established, further neurological and behavioral changes may result with additional parity and mothering. Recent research has shown that motherhood enhances both hippocampal-dependent learning and memory and oxytocin-induced long-term potentiation, suggesting that the hippocampus is affected by mothering. In turn, degree of maternal behavior, either high or low, has been shown to affect spatial learning and memory performance in adult offspring. The present experiment aimed to investigate the effect of reproductive experience (nulli-, primi-, and multiparity and mothering) and degree of maternal behavior on hippocampus-dependent learning and memory in the mother. Results show that regardless of error type, primiparous rats make fewer errors compared to nulliparous rats, while multiparous rats show a trend towards making fewer errors compared to nulliparous rats. In addition, mothers who spend less time licking and nursing offspring had fewer reference memory errors. Perhaps the enhanced learning and memory in the inexperienced, new mother allows her to effectively acquire the suite of maternal behaviors necessary to ensure offspring survival and achieve reproductive success with subsequent reproductive experience.

Animals↗

PubMed2003

Input and word learning: caregivers' sensitivity to lexical category distinctions.

Twenty-four caregivers and their two- to four-year-old children took part in a storybook reading task in which caregivers taught children novel labels ('DAXY') for familiar objects. One group (N = 12) received labels modelled syntactically as proper names ('This is named DAXY'), and another group (N = 12) received the same labels for the same objects modelled syntactically as adjectives ('This is very DAXY'). Caregivers took strikingly different approaches to teaching words from the two lexical categories. In teaching proper names, but not adjectives, caregivers flagged cases in which one word was paired with two objects; two words were paired with one object; and one word was paired with an inanimate object. In teaching adjectives, but not proper names, caregivers discussed meaning and offered translations. Caregivers' distinctive strategies for teaching proper names and adjectives are congruent with recent findings about children's word meaning assumptions, and with analyses of the semantics of these lexical categories. The findings indicate that parental speech could provide a rich source of information to children in learning how different lexical categories are expressed in their native language.

Adult↗