Changes in the local metabolism of dopamine in the anterior and neural lobes but not in the intermediate lobe of the pituitary gland during nursing

Dopamine (DA), produced by tubero-infundibular dopaminergic (TIDA) neurons of the arcuate nucleus (ARN) is the established inhibitor of the secretion of prolactin (PRL). Changes in dopaminergic (DAergic) neuronal activity in the median eminence–long portal vessels (ME–LPV) and/or the concentration of DA in the anterior lobe (AL) are inversely related to the secretion of PRL. However, conflicting reports concerning DAergic neuronal activity during the suckling-induced release of PRL persist. In addition to TIDA neurons, PeVN-hypophysial DAergic (PHDA) and tubero-hypophysial DAergic (THDA) neurons which, respectively, innervate the intermediate lobe (IL) and the IL/neural lobe (NL) also have a significant role. We measured the concentrations of DA and its main metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), in the median eminence and the three pituitary lobes of lactating mothers. Concentrations of DA and DOPAC from tissues and the concentration of PRL in plasma were measured by HPLC-EC and RIA, respectively. There were no changes in the concentration of DA and DOPAC of the IL due to the suckling stimulus. In the NL, a decrease in the concentration of DOPAC was detected due to the suckling stimulus. In addition, there were no changes of DA or DOPAC in the outer zone of the AL (AL-OZ) due to suckling. However, a decrease in the concentrations of DA and DOPAC was detected in the inner zone of the AL (AL-IZ). These data suggest lactotrophs from the AL-IZ are responsible for the changes in the concentration of plasma PRL in response to the suckling stimulus. In addition TIDA and THDA neurons, but not PHDA neurons, regulate the control of the secretion of PRL in response to suckling.     

A comparison of methods for determination of total lipids in human milk

A modified Folch extraction, a Celite-Na₂SO₄ column elution, a spectrophotometric method and the creamatocrit method for total lipid analysis of human milk were compared against the Roese-Gottlieb method. The constant, proportional and random errors associated with each method were determined. Pooled milk was centrifuged to separate milk lipid and skim milk. Varying concentrations of milk lipid were reintroudced into the skim milk to provide 25 samples for analysis with a range of lipids from approximately 0.5 to 8.0 percent. There was a high correlation (r>0.977) between the Roese-Gottlieb method and all methods evaluated. A least squares equation was developed between the Roese-Gottlieb method and each method tested. The greatest constant error, as estimated by the least squares y-intercept, was observed with the Celite Na₂SO₄ column procedure and spectrophotometric method. The greatest proportional error as estimated by the slope was observed with the Celite-Na₂SO₄ column procedure. Random error based on the least squares standard error of estimate in the y direction was greatest for the spectrophotometric method. While there are differences between methods, with careful standardization all the methods tested could provide satisfactory results for analysis of total lipids in human milk.     

Pattern of sucking in the infant rat during spontaneous milk ejection.

Two methods are described for measuring the sucking of rat pups on the nipples of the mother. The first uses pressure recording of the cannulated teatduct; the second uses direct observation of sucking behavior. Using these methods, the sucking behavior of the pups during sequences of milk ejections was investigated. Pressure recordings of the sucking of individual pups on the nipple showed that between milk ejections the pups sucked intermittently in bursts. During milk ejection itself there was a longer period of vigorous and continuous sucking. Behavioral observations on the level of sucking in whole litters of pups showed that the background bursts of sucking from the litter as a whole were randomly distributed in relation to the inferred time of oxytocin release. These results indicate that once the pups are sucking on the nipples, variations in the sucking behavior of the litter have no role in the timing of milk ejections in the mother.     

Role of vitamin D in maternal skeletal changes during pregnancy and lactation: A histomorphometric study

Summary The effect of vitamin D on bone changes during the reproductive cycle in female rats has been investigated. One group of female rats was maintained on a vitamin D-deficient diet and another group on a vitamin D-replete diet from weaning. Both groups were mated with normal males and changes in their bones were determined histomorphometrically during pregnancy, lactation, and after weaning. All vitamin D-deficient rats had bone changes typical of rickets. Pregnancy caused significant reductions in mineralized tissue of trabecular and cortical bone in the vitamin D-deficient rats. Lactation caused further significant reductions in mineralized tissues of cortical and trabecular bone in both the vitamin D-deficient and vitamin D-replete animals, with the greatest changes seen at weaning. Some restoration of mineralized tissues occurred following weaning. There was an increase in tetracycline-labeled bone surface in the vitamin D-replete animals during lactation, likely due to an increase in bone formation rates. In the vitamin D-deficient animals during lactation, there was a decrease in tetracyclinelabeled bone surface, likely due to severely depressed bone mineralization. These results indicate that the mobilization of calcium from bone to maintain pregnancy and lactation occurs by a mechanism independent of vitamin D.     

Breastfeeding: physiological, endocrine and behavioural adaptations caused by oxytocin and local neurogenic activity in the nipple and mammary gland

It is now well established that oxytocin, as well as stimulating uterine contractions and milk cjection, promotes the development of maternal behaviour and also bonding between mother and offspring. In addition, oxytocin exerts by way of peripheral, circulating as well as by central, neurogenic mechanisms multiple physiological, endocrine and behavioural effects in connection with milk ejection and lactation. Some effects of oxytocin in the nipple and mammary gland appear to be exerted in close collaboration with peptides released from axon collaterals of somatosensory nerves originating in this region. The distribution of peptides localized to the somatosensory afferents in the nipple and mammary gland as well as possible effects by oxytocin and/or local neurogenic peptides in connection with milk ejection and lactation are reviewed in this paper.     

Is Lactation A Risk Factor of IUD- and Sterilization-related Uterine Perforation? - A Hypothesis

A recent article reported a high risk of IUD-related uterine perforation in lactating women in the U.S. This article prompted the authors to examine the large international datasets on IUDs and tubal sterilizations collected by Family Health International. The findings are somewhat suggestive of such a positive association in IUD users as well as in women undergoing laparoscopic or minilaparotomy sterilization. More definitive studies are urged.     

The effects of first gestation and lactation on bone metabolism in dairy goats and milk sheep

The goal of the present study was to compare mobilization rate of calcium (Ca) from bone in pregnant and lactating goats and sheep. Blood samples were collected from goats and sheep monthly during pregnancy and at 1, 2, and 4 weeks postpartum (pp) and monthly during lactation until 6 months after parturition. Total bone mineral content (BMC) and total bone mineral density (BMD) were quantified using peripheral quantitative computed tomography at the same intervals as the blood was taken. Bone resorption was assessed by immunoassays quantitating two epitopes of the carboxyterminal telopeptide of type I collagen (ICTP, CTX). Bone formation was estimated by quantifying serum osteocalcin (OC) and bone-specific alkaline phosphatase (bAP). In addition, Ca and 1,25-dihydroxy vitamin D (1,25-VITD) concentrations were determined in serum.

Mean ICTP and CTX concentrations of both animal species increased the first week after parturition. By the second week pp, the concentrations of both markers had decreased toward early gestation levels. In contrast, mean OC concentrations continually decreased until the 1st week pp. By the 2nd week pp, the mean concentrations of OC started to increase again. Mean bAP activities decreased during gestation and reached a nadir in the first week pp in goats and 4 weeks pp in sheep. Afterwards, mean bAP activities increased again in goats and sheep. 1,25-VITD concentrations peaked the first week pp and returned to early gestation values thereafter. Total BMC and BMD decreased from the 4th month of pregnancy until the 1st week pp in both species. Afterwards, BMC increased throughout the first month pp in goats and the first 3 months pp in sheep. BMD levels of sheep and goats returned to prepartum levels during lactation.

The resorptive phase of bone remodeling is accelerated at parturition and in early lactation and is uncoupled from the process of bone formation. This allows the animal to achieve Ca homeostasis at the expense of bone. Increased bone remodeling during lactation may represent physiological mechanisms to help replace the maternal skeleton lost as the animal adapted to enormously increased Ca losses to the fetus and milk in late gestation and early lactation.     

Effects of malnutrition during the reproductive cycle on nutritional status and lactational performance of rat dams

To assess the effects of malnutrition imposed at various stages of the reproductive cycle on maternal nutritional status and lactational performance, rats were fed 50% of the intake of control animals fed adlibitum (C) either before pregnancy (R-B), before and during pregnancy (R-BP), during lactation (R-L) or throughout the experimental period (R-BPL). At day 14 of lactation, maternal plasma albumin and vitamin A, liver iron stores and carcass fat were reduced in the restricted animals (R-L, R-BPL). Vitamin A stores were lowest in the chronically malnourished rats and were not replenished by refeeding during lactation. Milk yield was compromised in the restricted rats; the acutely malnourished rats (R-L) were much more severely affected than those chronically underfed (R-BPL). The restricted animals (R-L, R-BPL) only partially compensated by producing a more nutrient-dense milk. As a result, only total daily output of milk lactose and iron were reduced in the restricted rats. Thus, nutritional insults occurring both before and during lactation influenced lactational performance. The negative effects of chronic malnutrition were largely overcome by refeeding during lactation.     

Amiodarone and the thyroid

Among the drugs affecting the thyroid gland, no drug has puzzled, and at the same time fascinated, endocrinologists more than amiodarone. Amiodarone is a potent class III anti-arrhythmic drug that also possesses beta-blocking properties. It is very rich in iodine, with a 100-mg tablet containing an amount of iodine that is 250 times the recommended daily iodine requirement. Amiodarone produces characteristic alterations in thyroid function tests in euthyroid patients. Understanding these alterations is crucial in avoiding unnecessary investigations and treatment. Amiodarone-induced thyroid dysfunction occurs because of both its iodine content and the direct toxic effects of the compound on thyroid parenchyma. Amiodarone-induced hyperthyroidism is more common in iodine-deficient regions of the world, whereas amiodarone-induced hypothyroidism is usually seen in iodine-sufficient areas. In contrast to amiodarone-induced hypothyroidism, amiodarone-induced thyrotoxicosis is a difficult condition to diagnose and treat. In this review, we discuss the alterations in thyroid function tests seen in euthyroid subjects, the epidemiology and mechanism of amiodarone-induced thyroid dysfunction, treatment options available, and the consequences of amiodarone use in pregnancy and lactation; and finally, we propose a follow-up strategy in patients taking amiodarone.     

类风湿关节炎患者妊娠期、围产期及哺乳期用药策略

随着新型生物制剂——肿瘤坏死因子抑制剂（TNFi）的广泛应用,更多RA患者病情可得到较好控制,因此有更多RA女性患者提出生育要求。本文总结了当前RA患者妊娠期、围产期及哺乳期相关药物治疗进展,给出了安全用药建议和药物治疗原则。我们建议提高RA育龄女性依从性,采取有计划的妊娠。风湿免疫科医生应当联合产科医生、儿科医生等相关人员,针对RA患者具体情况共同制定合理的个体化治疗方案,保证妊娠期及哺乳期间母子生命健康安全。妊娠期间禁用的药物有甲氨蝶呤（MTX）,来氟米特（LEF）,阿巴西普（ABA）和利妥昔单抗（RIT）。可应用至妊娠期的药物有肿瘤坏死因子抑制剂（TNFi）,双磷酸盐类（BP）。可应用于妊娠期间的控制病情药物有氯喹（CQ）/羟氯喹（HCQ）,柳氮磺吡啶（SSZ）,硫唑嘌呤（AZA）,环孢素A（CsA）。其他妊娠期可应用的药物有皮质类固醇激素（CS）,非甾体抗炎药（NSAIDs）。哺乳期能安全切有效控制RA病情的药物有NSAIDs,类固醇激素（Steroids）,HCQ,SSZ。