5th Postnatal Day Research Articles

DOPAMINE AND PROLACTIN CONTENT OF THE HUMAN MILK

Metoclopramide has been shown to increase milk production in humans. We investigated the daily milk production, the prolactin (PRL) and dopamine (DA) concentrations of the milk in mothers with (treated) or without (control) metoclopramide treatment (5 days, 30 mg/ day). Both groups consisted of 11 mothers and their full-term newborn infants. The daily milk production was significantly higher in the treated group (276.4±36.6 vs 150.9±25.3 ml/day, p<0.01). The PRL measured by RIA was similar in the milk samples of the metoclopramide treated and control groups (80.5±17.7 vs 90.7±27.3 ng/ml). The DA concentration in milk samples of treated mothers was significantly lower compared to the value of the control group (0.23±0.04 vs 0.41±0.07 pg/l, p<0.05). On the 5th postnatal day the level of serum PRL and DA of the newborns of mothers treated with metoclopramide did not differ from the values of the control babies, indicating that the amount of metoclopramide transferred into the milk has no apparent influence on the hypothalamo-hypophyseal axis of the neonate. Since the concentration of DA decreased in the milk of mothers treated with the DA receptor blocking agent metoclopramide|we suppose that the DA secretion into the milk is a receptor mediated process.

Expression of thyroglobulin gene in maternal and fetal thyroid in rats.

The relationship between the changes in thyroglobulin (Tg) mRNA and Tg proteins during thyroid development in the fetus and in maternal thyroid glands during gestation and lactation is studied. While the appearance of Tg mRNA (fetal day 15) showed good temporal correlation with that of 12S Tg, no 19S Tg could be detected until 3 days later. The 12S Tg was the predominant protein on days 18 and 19 of gestation in the fetus, while 19S Tg was the predominant protein on fetal days 21-22 and during the postnatal period in the offspring; by the 20th postnatal day, the 19S Tg content per gland was 4 times the amount of 12S (155 vs. 37 micrograms/gland; P less than 0.001). The 19S iodine content in the fetus was the same as that in 12S up to the 21st day of gestation, except for lower values on day 18. From fetal day 22 and through the postnatal period, the iodine content in 19S was 1.6-5.9 times greater than that in 12S. Therefore, the ratio of atoms of iodine per mol Tg during the experimental period changed from 0.75 to 19.5 for 19S and from 0.72 to 7.2 for 12S. The levels of all of the iodoamino acids were low on fetal days 17-19, after which they increased at different rates for each protein. The greatest increase in monoiodotyrosine and T3 corresponded to 12S, while diiodotyrosine and especially T4 showed a greater increase in 19S than in 12S Tg; 20 days after birth, the T4 content in 19S was about 3 times greater than that in 12S Tg. The soluble thyroid proteins from pregnant, lactating, and nonpregnant female controls contained a main protein, 19S, and a smaller amount of 27S. Both 19S Tg and 19S iodine contents were already lower than those in nonpregnant rats at 14 days of pregnancy, and the levels continued to decrease during the experimental period. In contrast, the 27S Tg and 27S iodine levels remained constant and similar to nonpregnant values. Surprisingly, a decrease in the level of Tg mRNA was observed during pregnancy and lactation. We have no explanation for the dramatic decrease in Tg mRNA during the last days of pregnancy. Further studies should help to elucidate the mechanism responsible for the changes in Tg gene expression in the thyroids of pregnant and lactating rats.

Expression of thyroglobulin gene in maternal and fetal thyroid in rats

The relationship between the changes in thyroglobulin (Tg) mRNA and Tg proteins during thyroid development in the fetus and in maternal thyroid glands during gestation and lactation is studied. While the appearance of Tg mRNA (fetal day 15) showed good temporal correlation with that of 12S Tg, no 19S Tg could be detected until 3 days later. The 12S Tg was the predominant protein on days 18 and 19 of gestation in the fetus, while 19S Tg was the predominant protein on fetal days 21-22 and during the postnatal period in the offspring; by the 20th postnatal day, the 19S Tg content per gland was 4 times the amount of 12S (155 vs. 37 micrograms/gland; P less than 0.001). The 19S iodine content in the fetus was the same as that in 12S up to the 21st day of gestation, except for lower values on day 18. From fetal day 22 and through the postnatal period, the iodine content in 19S was 1.6-5.9 times greater than that in 12S. Therefore, the ratio of atoms of iodine per mol Tg during the experimental period changed from 0.75 to 19.5 for 19S and from 0.72 to 7.2 for 12S. The levels of all of the iodoamino acids were low on fetal days 17-19, after which they increased at different rates for each protein. The greatest increase in monoiodotyrosine and T3 corresponded to 12S, while diiodotyrosine and especially T4 showed a greater increase in 19S than in 12S Tg; 20 days after birth, the T4 content in 19S was about 3 times greater than that in 12S Tg. The soluble thyroid proteins from pregnant, lactating, and nonpregnant female controls contained a main protein, 19S, and a smaller amount of 27S. Both 19S Tg and 19S iodine contents were already lower than those in nonpregnant rats at 14 days of pregnancy, and the levels continued to decrease during the experimental period. In contrast, the 27S Tg and 27S iodine levels remained constant and similar to nonpregnant values. Surprisingly, a decrease in the level of Tg mRNA was observed during pregnancy and lactation. We have no explanation for the dramatic decrease in Tg mRNA during the last days of pregnancy. Further studies should help to elucidate the mechanism responsible for the changes in Tg gene expression in the thyroids of pregnant and lactating rats.

Cortical synaptogenesis in congenitally hydrocephalic HTX-rats using monoclonal anti-synaptic vesicle protein antibody

We attempted to develop a method for investigating impairment of synaptogenesis quantitatively involving measurement of the fluorescence intensity emitted by immunohistochemically stained rat brain using a monoclonal antibody (Mab 171B5) against a synaptic vesicle protein (SVP-38). We applied this method to congenitally hydrocephalic and non-hydrocephalic brains of HTX-rats, and compared the postnatal changes in the fluorescence intensity in the molecular layer of the cerebral cortex. In non-hydrocephalic HTX-rats, the fluorescence intensity remained nearly unchanged from the 1st to 7th postnatal day and then increased at an almost linear rate until the 21st postnatal day, when it reached 4.5 times the value on the 7th postnatal day. The increase thereafter was gradual until the 28th postnatal day. In hydrocephalic HTX-rats, the fluorescence intensity increased nearly in parallel with that in non-hydrocephalic HTX-rats up to the 21st postnatal day. On the 28th postnatal day, the fluorescence intensity showed a marked reduction (P less than 0.01). This finding indicates that despite the presence of continuous pressure due to progressive ventricular dilatation after birth, synaptogenesis in the cerebral cortex may be relatively resilient.

Substance P and neurokinin A immunoreactive nerve fibres in the developing salivary glands of the rat.

The time of appearance and distribution of substance P (SP) and neurokinin A (NKA) immunoreactive nerve fibres in developing salivary glands of the rat were studied by the use of indirect immunohistochemical methods. The glands were examined at daily intervals from the 15th day in utero (i.u.) until birth, and subsequently on the 2nd, 5th, 7th, 12th, 16th and 30th postnatal day. The findings were compared to samples from adult. The first SP- and NKA-immunoreactive (IR) nerve fibres appeared on the 19th day i.u. in the parotid and submandibular glands and were abundantly distributed around developing ductal branches. In the mesenchyme around the developing ductal branches of the parotid gland the fibres appeared on the 20th day i.u. In the submandibular gland NKA-IR fibres appeared in the mesenchyme surrounding the developing ductal branches on the 19th day i.u. and SP-IR fibres on the 21st day i.u. Around blood vessels of both glands, SP- and NKA-IR fibres made their appearance only much later, on the second postnatal day. The number of SP- and NKA-IR nerve fibres in the developing salivary glands was already high on the 19th day i.u. when they were first detected. From this point up to the 16th postnatal day the glands were richly innervated by the fibres, but later the numbers slowly decreased to adult levels. The abundance of SP- and NKA-IR nerve fibres especially around the ductal branches and secretory structures in the developing salivary glands suggests a role in the functional maturation of salivary glands.

Postnatal development of the rabbit pineal gland. A light- and electron-microscopic study.

The development of the rabbit pineal gland has been studied by light and electron microscopy from the 1st to the 120th postnatal day. After 24 h of postnatal life, the pineal parenchyma is highly cellular, showing two identifiable cell types: pinealocytes I and II. Immature type II pinealocytes arrange either in cellular cords or clusters or forme rosette-like structures. At the 5th postnatal day, corticomedullar differentiation is established. Rosette-like structures and cellular cords are absent from the cortex. Along the postnatal period, nuclei of pinealocytes are set apart due to cytoplasmic widening and development of cell processes. These structures pervade the cellular cords and rosette-like structures formed by immature type II pinealocytes. Rosette-like structures are no longer seen beyond the 30th postnatal day, and cords of type II pinealocytes from the 90th postnatal day on. At this time, the rabbit pineal gland is considered to be histologically mature.

Prenatally administered delta-9-tetrahydrocannabinol temporarily inhibits the developing hypothalamo-pituitary system in rats

We have reported earlier that Δ 9-tetrahydrocannabinol (THC) if injected over the 3rd week of pregnancy with a daily dose of 1 μg/kg b.wt., caused a significant prolongation of pregnancy and 42% of stillbirths, although no teratological effects were observed. In the present study, we investigated the postnatal development of hypothalamo-hypophyseal-gonadal axis of the above mentioned rats' living litters. The rats were killed every 5th day between the delivery (D0) and the 20th postnatal day (D20). The weight of the body and the gonads was measured and hormonal parameters were registered by RIAs. The body weight was lower in treated animals, with a higher degree in males. The weight of the gonads also decreased. Serum testosterone levels were lower in rats from D0 till D10, while at D15 and D20 no differences were recorded between controls and treated rats. No significant differences were observed in serum estrogen levels during the investigated period. Serum progesterone decreased up to D10. Pituitary luteinizing hormone (LH) diminished postpartum in both sexes up to D5. From D0 till D5, serum LH increased in males while it decreased in females. Hypothalamic luteinizing hormone releasing hormone decreased up to D15 in both sexes, less markedly in females than in males. The nerupeptide Y content of the hypothalamus was also decreased in early postnatal age. We concluded that a very low dose of prenatally administered THC caused transitory inhibition of the developing hypothalamo-pituitary-gonadal axis, i.e., postnatal changes were evoked in the neuroendocrine system. By the 20th postnatal day this effect of THC seemed to be eliminated.

The effect of squatting on pelvic dimensions

Lateral X-ray pelvimetry was performed on 63 women in the sitting and squatting positions on the 5th or 6th post-natal day to assess whether squatting has any effect on pelvic dimensions. Four assessors measured the inlet and outlet pelvic dimensions from 25 cases with good radiographic views in order to minimise observer bias. There was no statistically significant change in pelvic dimensions with squatting. Some possible explanations are discussed.

Development of glial fibrillary acidic protein immunoreactivity in thyroidectomized rats

The majority of astroglia develop postnatally in rats. GFAP (glial fibrillary acidic protein)-immunoreactivity appears mainly during the 2nd and 3rd postnatal weeks throughout the brain. Hypothyroidism inhibits, among others, the cell proliferation, maturation, and migration of neurons. However, hardly any data on the effect of hypothyroidism on GFAP-immunoreactivity are available in the literature. In our experiments, thyroidectomy was performed between the 3rd and 5th postnatal days. Operated and control animals from the same litter were perfused transcardially and processed for immunohistochemistry in parallel after 2, 3, and 4 wk. On the basis of serial sections, the development of GFAP-immunoreactivity was not generally affected by hypothyroidism. We could observe only two phenomena that showed a tendency of retardation in the operated animals: (1) the decrease of the strong GFAP-immunopositivity of white matter tracts (for example, internal capsule and pyramidal tract) and (2) the gradual disappearance of the GFAP-immunoreactive radial fibers (for example, in the neocortex, in the olfactory bulb, and around the 3rd ventricle).

ChAT-like immunoreactivity of olivocochlear fibres on rat outer hair cells during the postnatal development

Several studies present a great deal of information about putative efferent neurotransmitters and their distribution in the adult and developing cochlea. Anatomical mapping of outer hair cell efferent fibres during ontogeny is still not available. Using quantitative electron microscopy in combination with immunocytochemistry, the distribution of ChAT-like immunoreactivity in the developing rat was investigated. Adult-like immunoreactivity in the whole cochlea is first observed in 30-day-old rats. We localized the adult-like immunoreactivity in all efferent fibres and synapses of the outer hair cells along the entire cochlear duct. An adult-like reaction in the whole cochlea could be observed on the 25th day after birth in two out of three cases. On the 20th postnatal day, no adult-like ChAT immunoreactivity was found, with the exception of one case where labelling was seen in the basal region only. The adult-like ChAT immunoreactivity on the 30th day, 2-3 weeks after the onset of hearing, is the latest maturation of all features of the organ of Corti so far investigated. Synaptogenesis of the outer hair cell efferents reaches an adult-like appearance already on the 16th day after birth.

An enzyme-linked immunosorbent assay for myelin basic protein-specific protein methylase I

A sandwich enzyme-linked immunosorbent assay (ELISA) has been developed to determine myelin basic protein (MBP)-specific protein methylase I. Rabbit immunoglobulin anti-bovine MBP-specific protein methylase I, purified by Sepharose-A affinity chromatography, was utilized as the primary antibodies, while the same antibodies which had been conjugated to peroxidase were employed as the indicator antibodies. This assay method was about 280 times more sensitive than the conventional trichloroacetic acid (TCA) precipitation method. Employing the ELISA, the level of MBP-specific protein methylase I during mouse brain development was examined; the peak level of the methylase was shown to be at 16th postnatal day, indicating temporal correlation with myelination. Among several species of brains examined, human showed the highest and carp the least amount of MBP-specific protein methylase I; 6.33 μg and 0.33 μg per mg of brain cytosol protein, respectively. Dysmyelinating jimpy hemizygous mouse brain showed the immunoreactive MBP-specific protein methylase only 60% that of the control at 20 days of age. The high sensitivity of the method together with the fact that MBP-specific protein methylase is present in human cerebrospinal fluid suggests a possible clinical application of this method for evaluating demyelinating disorders.

Neurotoxic effects of two different pyrethroids, bioallethrin and deltamethrin, on immature and adult mice: Changes in behavioral and muscarinic receptor variables

We have recently shown that two pyrethroids, bioallethrin and deltamethrin, affect muscarinic cholinergic receptors (MAChR) in the neonatal mouse brain when given to suckling mice during the period of rapid brain growth. Such early exposure to these pyrethroids can also lead to permanent changes in the MAChR and behavior in the mice as adults. In the present study, male NMRI mice were given bioallethrin (0.7 mg), deltamethrin (0.7 mg), or a 20% fat emulsion vehicle (10 ml) per kilogram of body weight per os once daily between the 10th and 16th postnatal day. The mice were subjected to behavioral tests upon reaching the age of 17 days and at 4 months. Within 1–2 weeks after the behavioral tests the mice were killed by decapitation and crude synaptosomal fractions (P2) were prepared from the cerebral cortex, hippocampus, and striatum. The densities of MAChR were assayed by measuring the amounts of quinuclidinyl benzilate ([ 3H]QNB) specifically bound in the P2 fraction. The proportions of high-affinity (HA) and low-affinity (LA) binding sites of MAChR were assayed in a displacement study using [ 3H]QNB/carbachol. The behavioral tests at an adult age of 4 months indicated a significant increase in spontaneous motor behavior in both bioallethrin- and deltamethrin-treated mice. There was also a significant decrease and a tendency toward a decrease in the density of MAChR in the cerebral cortex in mice receiving bioallethrin and deltamethrin, respectively. The proportions of HA- and LA-binding sites of MAChR were not changed. This study further supports that disturbances of the cholinergic system during rapid development in the neonatal mouse can lead to permanent changes in cholinergic and behavioral variables in the animals as adults.

Effects of early postnatal handling on brain β-adrenoceptors and behavior in tests related to stress

The present study investigated the effects of early postnatal handling and temporary maternal isolation, between the 5th and 20th postnatal days, on various behaviors related to stress measured in adulthood in male Wistar rats. In addition, β-adrenoceptor binding in the brain was measured. The handling consisted of daily 3-min sessions during which a pup was gently held by an investigator. The isolated rat pups were kept separated from their nursing mothers for 1 h daily. Subsequently, it was found that the time spent immobile in Porsolt's swim test was shortened, and voluntary alcohol (5% v/v) consumption was reduced in the handled rats, as compared with the non-handled and isolated animals. No differences in the measure of anxiety — food consumed in a novel environment — or the time spent in social, aggressive and defensive behaviors in a resident-intruder paradigm, were noted. Neither did the density or affinity of β-adrenoceptors in the frontal cortex or hippocampus differ significantly between the groups. The results indicate that short-lasting maternal separation does not cause sustained effects on behavior in the rat. Early postnatal handling leads to shortened immobility in the swim test and reduced voluntary alcohol consumption, suggesting that handled rats show an improved ability to cope with stress.

Effect of Protein Malnutrition on Glycoprotein, Protein and Lipid Synthesis in the Rat Cerebellum during the Period of Brain Growth Spurt

Female Wistar rats were fed a normal-protein diet (25% casein) or a low-protein diet (8% casein) during pregnancy and lactation. The two diets were isocaloric and contained appropriate amounts of mineral salts and vitamins. Pups from dams submitted to the low-protein diet had a lower body weight than normally fed controls as early as on the day of birth, but a difference in cerebellar weight between the two groups was observed only on the 15th postnatal day. Malnutrition had no effect on cerebellar protein concentration, which increased with age in both groups. The cerebellar DNA concentration was higher at 7 and 15 days of age in normally fed rats than in malnourished rats, whereas at 21 days of age it was higher in the malnourished animals. [U-14C]Leucine and [2-3H]mannose incorporation into proteins and lipid synthesis from acetyl coenzyme A (CoA) derived from [U-14C]leucine markedly decreased with age in the cerebellum of rats fed both diets. [2-3H]Mannose incorporation into cerebellar glycoproteins was greater in malnourished rats during the period of brain growth spurt than in normally fed rats at all ages studied. Prenatal and postnatal protein malnutrition had no effect on [U-14C]leucine incorporation into cerebellar proteins or on cerebellar lipid synthesis from acetyl-CoA derived from [U-14C]leucine during the period of brain growth spurt.

Thyroid hormone regulation of Na,K-ATPase subunit-mRNA expression in neonatal rat myocardium.

Regulation of Na,K-ATPase mRNA alpha isoform and mRNA beta expression by thyroid hormone (T3) in neonatal rat myocardium was examined. In euthyroid neonates between ages of 2 and 5 days, mRNA alpha 1, mRNA alpha 3, and mRNA beta 1 abundances were nearly constant while mRNA alpha 2 was undetectable. During the interval between postnatal days 5 and 15, mRNA alpha 3 decreased to negligible levels and mRNA alpha 2 became expressed and increased in abundance to account for approximately 20% of the mRNA alpha pool by the 15th postnatal day. To examine the effect of T3 on this developmental program, neonates were injected with 75 micrograms T3/100 g body weight or diluent alone on the second and third postnatal days and myocardial Na,K-ATPase subunit-mRNA abundances were determined on the third and fourth postnatal days. Because T3 treatment increased the RNA/DNA ratios of myocardial tissue, the subunit-mRNA abundances were normalized per unit DNA. Following 24 and 48 hr of T3 treatment, the abundances of mRNA alpha 1, mRNA alpha 3, and mRNA beta 1 increased, while mRNA alpha 2 continued to remain undetectable during the 2-day interval between the second to fourth postnatal days. It is concluded that T3 augments the abundance of Na,K-ATPase subunit mRNAs that are already being expressed in the neonatal rat myocardium. The results further suggest that T3 does not act as a "molecular switch" in the developmental expression of the mRNA alpha isoforms in rat myocardium during the first four postnatal days.

Localization of 5-HT1A serotonin receptors in the cerebellum of young rats

Abstract Previous studies have shown that functional 5-HT 1A receptors are present in the cerebellum only for the early postnatal period in rats. In order to investigate further the possible physiological significance of such a transient expression of 5-HT 1A receptors during maturation of the cerebellum, anatomical studies were performed for identifying which cell type(s) are endowed with these receptors in 8-day-old rats. Autoradiography (using [ 125 I]BH-8-MeO-N-PAT) with dry films and emulsion-coated coverslips, and radioimmunohistochemistry (using specific polyclonal anti-5-HT 1A receptor antibodies) of vermis sections revealed that 5-HT 1A receptors were mainly concentrated in the molecular layer of the anterior part of the lobule X and the posterior part of the lobule IXB. X-Irradiation on the 5th postnatal day yielded an agranular cerebellum whose density of 5-HT 1A sites was higher than that in age-paired control animals. These data indicate that 5-HT 1A receptors are not located on granule cells, but probably on glial cells in the molecular layer of the immature cerebellum. This location further supports the possible implication of glial 5-HT 1A receptors in some trophic action of 5-HT during CNS maturation.

CHANGES IN WHOLE BRAIN MEMBRANES OF RATS FOLLOWING PRE- AND POST-NATAL EXPOSURE TO ETHANOL

The chronic effects of ethanol on the fatty acid composition of rats that have been exposed to ethanol in utero were examined. Ten female Wistar rats were fed a nutritionally adequate liquid diet for 3 weeks before mating, throughout gestation and until the offspring reached the 10th or 20th post-natal day. Whole brain lipid changes were examined at these 2 time points. On day 10, a decrease in 18:1 lipid content was found, indicating tolerance development. However, by day 20 an increase in polyunsaturated fatty acid content (20:4) was detected, indicating that ethanol may be causing an increase in membrane fluidity. Although these results are contrary to those found in adult rats following chronic ethanol administration, it seems likely that, in the immature animal, the brain is still undergoing rapid development and therefore may be affected differentially by ethanol.

Muscle‐specific response to thyroid hormone of myosin isoform transitions during rat postnatal development

Transitions from embryonic and neonatal to adult-type-II isomyosins are known to be related to the increase in the thyroid hormone plasma concentration during postnatal development. These transitions have been shown, however, to occur at different times, depending on the muscle, suggesting that each muscle responds differently to the thyroid hormone. We have investigated quantitatively the effects of experimental hypothyroidism and hyperthyroidism on isomyosin transitions from birth until the 45th postnatal day in eight rat muscles: diaphragm, intercostals, gastrocnemius medialis, soleus, plantar muscles of the foot, tongue muscle, levator ani and bulbocavernosus complex, and masseter. Hypothyroidism delayed the isomyosin transitions in all the muscles examined, particularly in the sexually dimorphic muscles (levator ani and bulbocavernosus complex and masseter). However, it did not eventually inhibit isomyosin transitions, indicating that the thyroid hormone was not an absolute requirement for these to occur. Hyperthyroidism had only a slight effect on isomyosin transition in the diaphragm, and accelerated such transitions in the other muscles. The transition curves of all the muscles investigated, except those of the sexually dimorphic muscles, became similar to that of the diaphragm, demonstrating that the various muscles did not display the same sensitivity to the thyroid hormone but were regulated by it in the same way. The isomyosin transitions in the sexually dimorphic muscles remained late in comparison to that in the diaphragm, which suggests a more complex regulation. The effect of hyperthyroidism was not permanent and could be reversed, by interruption of the treatment, to a greater or lesser extent depending on the muscle. In all muscles containing slow-type-I isomyosin, hypothyroidism had no effect on this isomyosin synthesis, whereas hyperthyroidism inhibited it. This inhibition ceased rapidly after the interruption of the treatment.

Mullerian Inhibiting Substance Ontogeny and its Modulation by Follicle-Stimulating Hormone in the Rat Testes*

Mullerian Inhibiting Substance (MIS) production in rat testes from the late fetal to the adult period and its modulation by gonadotropins in neonatal testes were studied using immunohistochemistry, northern analysis, and a graded organ culture bioassay for MIS. The intense immunohistochemical staining for MIS seen in fetal and newborn testes began to decrease gradually after the third postnatal day, then decreased dramatically on the fifth postnatal day. MIS immunohistochemical activity was then present at a low level until about the 20th postnatal day, after which it was barely detectable. The testes from rats treated with FSH at birth showed a considerable drop in MIS immunohistochemical activity on the third postnatal day to 29% of control testes, and a less profound decrease on the second and fourth postnatal days to 46% and 61% of control, respectively; thereafter MIS levels were the same in treated and untreated animals. With shorter courses of FSH treatment, immunohistochemical staining showed less depression of MIS on the third day, and no difference by the fourth postnatal day, indicating that the inhibitory effect on testicular MIS production may require continued FSH exposure. Three-day testes that had been treated with FSH for 2-1/2 days had less MIS messenger RNA compared to control testes of the same age, suggesting that the inhibitory effect of FSH on MIS production could be transcriptionally mediated. In contrast LH treatment produced no difference in either messenger RNA expression or immunohistochemical staining for MIS. These findings suggested that FSH may be a modulator of MIS production in neonatal testes.

49 MATERNAL METOCLOPRAMIDE TREATMENT AND PROLACTIN CONCENTRATION IN HUMAN MILK

The breast milk prolactin (PRL) has been claimed to play a role in the control of electrolyte composition of the milk. Since metoclopramide has been shown to increase milk production in humans, we have made an attempt to investigate the production, the PRL and sodium concentrations in milk with and without maternal metoclopramide treatment (5 days, 30 mg/day). Both groups consisted of 11 mothers and their full-term newborn infants. The daily milk production was significantly higher in the treated group (276.4 ± 36.6 vs 150.9 ± 25.3 ml/day, p<0.01). The PRL measured by RIA was similar in the milk samples of the metoclopramide treated and control groups (80.5 ± 17.7 vs 90.7 ± 27.3 ng/ml). The sodium concentration in the milk of mothers taking metcclopramide was 22.1 ± 1.6 mmol/l and 24.3 ± 3.2 mmol/l in the control group (p=0.59). On the 5th postnatal day the plasma PRL of the newborns of mothers treated with metoclopramide does not differ from the value of the control babies (29.8 ± 2.6 vs 30.7 ± 2.4 ng/ml) indicating that the amount of metoclopramide transferred into the milk has no apparent influence on the hypothalamo-hypophyseal axis of the neonate. In conclusion: the maternal metoclopramide treatment augments the milk production without having any effect on the PRL and sodium concentration of human “mature” milk.