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Lactating Rat (lactating + rat)

Distribution by Scientific Domains
Medical Sciences55%

Selected Abstracts

Disruption of Maternal Behavior by Alcohol Intoxication in the Lactating Rat: A Behavioral and Metabolic Analysis

ALCOHOLISM, Issue 8 2002
Marta Yanina Pepino
Background Preweanling rats exhibit clear behavioral signs of distress after interacting with an alcohol-intoxicated dam. Interestingly, behavioral reactivity of infants to the experience of alcohol in the nursing context decreases as a function of repeated alcohol administrations to the mother. In this study, maternal activities were examined when dams were exposed to repeated administrations of a subnarcoleptic alcohol dose. Maternal changes in alcohol metabolism were also analyzed as a function of repeated exposures to the drug. Methods During postpartum days 3, 5, 7, 9, 11, and 13, nursing dams received an intragastric administration of either 2.5 g/kg of alcohol or water. Maternal behaviors were evaluated (experiment 1). Blood alcohol levels (BALs) of the dams were determined on postpartum day 16 after all mothers received either an intragastric (experiment 2) or an intraperitoneal (experiment 3) dose of alcohol. The doses used (2.5 g/kg intragastrically and 1.5 g/kg intraperitoneally) were chosen because they promote similar peak BALs in dams naive to alcohol. Results Maternal behaviors were strongly affected by the state of intoxication. Nevertheless, these disruptions clearly subsided with progression of alcohol-related experiences (experiment 1). Chromatographic analysis of alcohol metabolism indicated the development of tolerance in dams that had prior experience with alcohol (experiment 2). Changes in BALs as a function of prior experience with alcohol seemed related to first-pass alcohol metabolism rather than hepatic oxidative processes of the drug (experiments 2 and 3). Conclusions When the dam first experiences a moderate state of alcohol intoxication, maternal behaviors are uniformly disrupted. Subsequent exposures to alcohol lead to maternal metabolic tolerance. In conjunction with previous studies, these data indicate that infantile reactivity to alcohol is dependent on how the members of the dam/pup dyad express or perceive ethanol's postabsorptive effects. [source]

Expression of GABAB Receptors in Magnocellular Neurosecretory Cells of Male, Virgin Female and Lactating Rats

JOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2005
D. S. Richards
Abstract GABA is one of the key neurotransmitters that regulate the firing activity of neurones in the supraoptic (SON) and paraventricular (PVN) nuclei. In the present study, we used immunohistochemical techniques to study the distribution and subcellular localisation of metabotropic GABAB receptors in magnocellular neurones in the SON and PVN. Robust GABAB receptor immunoreactivity (GABABR; both subunit 1 and subunit 2 of the heterodimer), was observed in the SON and PVN. At the light microcope level, GABABR immonoreactivity displayed a clustered pattern localised both intracytoplasmically and at the plasma membrane. Densitometry analysis indicated that GABABR immunoreactivity was significantly more intense in vasopressin cells than in oxytocin cells, both in male, virgin female and lactating rats, and was denser in males than in virgin females. Light and electron microscope studies indicated that cytoplasmic GABABR was localised in various organelles, including the Golgi, early endosomes and lysosomes, suggesting the cycling of the receptor within the endocytic and trafficking pathways. Some smaller clusters at the level of the cell plasma membrane were apposed to glutamic acid decarboxylase 67 immunoreactive boutons, and appeared to be colocalised with gephyrin, a constituent protein of the postsynaptic density at inhibitory synapses. The presence of GABABR immunoreactivity at synaptic and extrasynaptic sites was supported by electron microscopy. These results provide anatomical evidence for the expression of postsynaptic GABAB receptors in magnocellular neurosecretory cells. [source]

Distribution of carbon-14 labeled C60 ([14C]C60) in the pregnant and in the lactating dam and the effect of C60 exposure on the biochemical profile of urine

JOURNAL OF APPLIED TOXICOLOGY, Issue 4 2010
Susan C. J. Sumner
Abstract This study was conducted to determine the distribution of [14C]C60 in the pregnant rat and fetuses, and in the lactating rat and offspring. Pregnant rats were dosed on gestation day (gd) 15 and lactating rats were dosed on postnatal day (pnd) 8 via tail vein injection with a suspension of ,0.3,mg [14C]C60,kg,1 body weight prepared in polyvinylpyrrolidone (PVP), or with PVP alone. Tissues were collected at 24 and 48 h after dosing. The largest portion of the administered dose was detected in the liver (,43%, pregnant dam; ,35%, lactating dam) and lung (,25%, lactating dam). Radioactivity (,6%) was distributed to the reproductive tract, placenta and fetuses of the pregnant dam. Lactating rats had radioactivity distributed to the milk (3140,dpm,g,1 tissue, 24,h; 1620,dpm,g,1 tissue, 48,h), and to the pups' GI tract (2.8%, 24,h; 4.4% 48,h) and liver (<1%). Blood radioactivity was significant at 24,h (14,19%) and at 48,h (7%) after dosing; largely accounted for in the plasma fraction. Less that 4% of the dose was recovered in the maternal spleen, heart, brain, urine or feces. Metabolomics analysis of urine indicated that dams exposed to [14C]C60 had decreased metabolites derived from the Krebs cycle and increased metabolites derived from the urea cycle or glycolysis, as well as alterations in the levels of some sulfur-containing amino acids and purine/pyrimidine metabolites. This study demonstrated that [14C]C60 crosses the placenta and is transmitted to offspring via the dam's milk and subsequently systemically absorbed. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Brain mechanisms underlying emotional alterations in the peripartum period in rats

DEPRESSION AND ANXIETY, Issue 3 2003
Inga D. Neumann
Abstract In the period before and after parturition, i.e., in pregnancy and lactation, a variety of neuroendocrine alterations occur that are accompanied by marked behavioral changes, including emotional responsiveness to external challenging situations. On the one hand, activation of neuroendocrine systems (oxytocin, prolactin) ensures reproduction-related physiological processes, but in a synergistic manner also ensures accompanying behaviors necessary for the survival of the offspring. On the other hand, there is a dramatic reduction in the responsiveness of neuroendocrine systems to stimuli not relevant for reproduction, such as the hypothalamo-pituitary-adrenal (HPA) axis responses to physical or emotional stimuli in both pregnant and lactating rats. With CRH being the main regulator of the HPA axis, downregulation of the brain CRH system may result in various behavioral, in particular emotional, adaptations of the maternal organisms, including changes in anxiety-related behavior. In support of this, the lactating rat becomes less emotionally responsive to novel situations, demonstrating reduced anxiety, and shows a higher degree of aggressive behavior in the test for agonistic behavior as well as in the maternal defense test. These changes in emotionality are independent of the innate (pre-lactation) level of anxiety and are seen in both rats bred for high as well as low levels of anxiety. Both brain oxytocin and prolactin, highly activated at this time, play a significant role in these behavioral and possibly also neuroendocrine adaptations in the peripartum period. Depression and Anxiety 17:111,121, 2003. © 2003 Wiley-Liss, Inc. [source]

Glutamatergic input governs periodicity and synchronization of bursting activity in oxytocin neurons in hypothalamic organotypic cultures

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2003
Jean-Marc Israel
Abstract During suckling, oxytocin (OT) neurons display a bursting electrical activity, consisting of a brief burst of action potentials which is synchronized throughout the OT neuron population and which periodically occurs just before each milk ejection in the lactating rat. To investigate the basis of such synchronization, we performed simultaneous intracellular recordings from pairs of OT neurons identified retrospectively by intracellular fluorescent labelling and immunocytochemistry in organotypic slice cultures derived from postnatal rat hypothalamus. A spontaneous bursting activity was recorded in 65% of OT neurons; the remaining showed only a slow, irregular activity. Application of OT triggered bursts in nonbursting neurons and accelerated bursting activity in spontaneously bursting cells. These cultures included rare vasopressinergic neurons showing no bursting activity and no reaction to OT. Bursts occurred simultaneously in all pairs of bursting OT neurons but, as in vivo, there were differences in burst onset, amplitude and duration. Coordination of firing was not due to electrotonic coupling because depolarizing one neuron in a pair had no effect on the membrane potential of its partner and halothane and proprionate did not desynchronize activity. On the other hand, bursting activity was superimposed on volleys of excitatory postsynaptic potentials (EPSPs) which occurred simultaneously in pairs of neurons. EPSPs, and consequently action potentials, were reversibly blocked by the non-NMDA glutamatergic receptor antagonist CNQX. Taken together, these data, obtained from organotypic cultures, strongly suggest that a local hypothalamic network governs synchronization of bursting firing in OT neurons through synchronous afferent volleys of EPSPs originating from intrahypothalamic glutamatergic inputs. [source]

Distribution of carbon-14 labeled C60 ([14C]C60) in the pregnant and in the lactating dam and the effect of C60 exposure on the biochemical profile of urine

JOURNAL OF APPLIED TOXICOLOGY, Issue 4 2010
Susan C. J. Sumner
Abstract This study was conducted to determine the distribution of [14C]C60 in the pregnant rat and fetuses, and in the lactating rat and offspring. Pregnant rats were dosed on gestation day (gd) 15 and lactating rats were dosed on postnatal day (pnd) 8 via tail vein injection with a suspension of ,0.3,mg [14C]C60,kg,1 body weight prepared in polyvinylpyrrolidone (PVP), or with PVP alone. Tissues were collected at 24 and 48 h after dosing. The largest portion of the administered dose was detected in the liver (,43%, pregnant dam; ,35%, lactating dam) and lung (,25%, lactating dam). Radioactivity (,6%) was distributed to the reproductive tract, placenta and fetuses of the pregnant dam. Lactating rats had radioactivity distributed to the milk (3140,dpm,g,1 tissue, 24,h; 1620,dpm,g,1 tissue, 48,h), and to the pups' GI tract (2.8%, 24,h; 4.4% 48,h) and liver (<1%). Blood radioactivity was significant at 24,h (14,19%) and at 48,h (7%) after dosing; largely accounted for in the plasma fraction. Less that 4% of the dose was recovered in the maternal spleen, heart, brain, urine or feces. Metabolomics analysis of urine indicated that dams exposed to [14C]C60 had decreased metabolites derived from the Krebs cycle and increased metabolites derived from the urea cycle or glycolysis, as well as alterations in the levels of some sulfur-containing amino acids and purine/pyrimidine metabolites. This study demonstrated that [14C]C60 crosses the placenta and is transmitted to offspring via the dam's milk and subsequently systemically absorbed. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Brain mechanisms underlying emotional alterations in the peripartum period in rats

DEPRESSION AND ANXIETY, Issue 3 2003
Inga D. Neumann
Abstract In the period before and after parturition, i.e., in pregnancy and lactation, a variety of neuroendocrine alterations occur that are accompanied by marked behavioral changes, including emotional responsiveness to external challenging situations. On the one hand, activation of neuroendocrine systems (oxytocin, prolactin) ensures reproduction-related physiological processes, but in a synergistic manner also ensures accompanying behaviors necessary for the survival of the offspring. On the other hand, there is a dramatic reduction in the responsiveness of neuroendocrine systems to stimuli not relevant for reproduction, such as the hypothalamo-pituitary-adrenal (HPA) axis responses to physical or emotional stimuli in both pregnant and lactating rats. With CRH being the main regulator of the HPA axis, downregulation of the brain CRH system may result in various behavioral, in particular emotional, adaptations of the maternal organisms, including changes in anxiety-related behavior. In support of this, the lactating rat becomes less emotionally responsive to novel situations, demonstrating reduced anxiety, and shows a higher degree of aggressive behavior in the test for agonistic behavior as well as in the maternal defense test. These changes in emotionality are independent of the innate (pre-lactation) level of anxiety and are seen in both rats bred for high as well as low levels of anxiety. Both brain oxytocin and prolactin, highly activated at this time, play a significant role in these behavioral and possibly also neuroendocrine adaptations in the peripartum period. Depression and Anxiety 17:111,121, 2003. © 2003 Wiley-Liss, Inc. [source]

Distribution of carbon-14 labeled C60 ([14C]C60) in the pregnant and in the lactating dam and the effect of C60 exposure on the biochemical profile of urine

JOURNAL OF APPLIED TOXICOLOGY, Issue 4 2010
Susan C. J. Sumner
Abstract This study was conducted to determine the distribution of [14C]C60 in the pregnant rat and fetuses, and in the lactating rat and offspring. Pregnant rats were dosed on gestation day (gd) 15 and lactating rats were dosed on postnatal day (pnd) 8 via tail vein injection with a suspension of ,0.3,mg [14C]C60,kg,1 body weight prepared in polyvinylpyrrolidone (PVP), or with PVP alone. Tissues were collected at 24 and 48 h after dosing. The largest portion of the administered dose was detected in the liver (,43%, pregnant dam; ,35%, lactating dam) and lung (,25%, lactating dam). Radioactivity (,6%) was distributed to the reproductive tract, placenta and fetuses of the pregnant dam. Lactating rats had radioactivity distributed to the milk (3140,dpm,g,1 tissue, 24,h; 1620,dpm,g,1 tissue, 48,h), and to the pups' GI tract (2.8%, 24,h; 4.4% 48,h) and liver (<1%). Blood radioactivity was significant at 24,h (14,19%) and at 48,h (7%) after dosing; largely accounted for in the plasma fraction. Less that 4% of the dose was recovered in the maternal spleen, heart, brain, urine or feces. Metabolomics analysis of urine indicated that dams exposed to [14C]C60 had decreased metabolites derived from the Krebs cycle and increased metabolites derived from the urea cycle or glycolysis, as well as alterations in the levels of some sulfur-containing amino acids and purine/pyrimidine metabolites. This study demonstrated that [14C]C60 crosses the placenta and is transmitted to offspring via the dam's milk and subsequently systemically absorbed. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Expression of GABAB Receptors in Magnocellular Neurosecretory Cells of Male, Virgin Female and Lactating Rats

JOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2005
D. S. Richards
Abstract GABA is one of the key neurotransmitters that regulate the firing activity of neurones in the supraoptic (SON) and paraventricular (PVN) nuclei. In the present study, we used immunohistochemical techniques to study the distribution and subcellular localisation of metabotropic GABAB receptors in magnocellular neurones in the SON and PVN. Robust GABAB receptor immunoreactivity (GABABR; both subunit 1 and subunit 2 of the heterodimer), was observed in the SON and PVN. At the light microcope level, GABABR immonoreactivity displayed a clustered pattern localised both intracytoplasmically and at the plasma membrane. Densitometry analysis indicated that GABABR immunoreactivity was significantly more intense in vasopressin cells than in oxytocin cells, both in male, virgin female and lactating rats, and was denser in males than in virgin females. Light and electron microscope studies indicated that cytoplasmic GABABR was localised in various organelles, including the Golgi, early endosomes and lysosomes, suggesting the cycling of the receptor within the endocytic and trafficking pathways. Some smaller clusters at the level of the cell plasma membrane were apposed to glutamic acid decarboxylase 67 immunoreactive boutons, and appeared to be colocalised with gephyrin, a constituent protein of the postsynaptic density at inhibitory synapses. The presence of GABABR immunoreactivity at synaptic and extrasynaptic sites was supported by electron microscopy. These results provide anatomical evidence for the expression of postsynaptic GABAB receptors in magnocellular neurosecretory cells. [source]