Biomedical subjects
I Rothchild
Publications and source records attributed to I Rothchild.
A quantitative relation between the experimentally determined number of conceptuses and corpus luteum activity in the pregnant rat.
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Conversion of progesterone to testosterone in the rat Leydig cell.
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The attenuation of prostaglandin-induced luteolysis in decidual tissue-bearing pseudopregnant rats.
Decidual tissue (DT)-bearing pseudopregnancy (PSP) rats, in contrast to hysterectomized PSP rats, were resistant to a luteolytic regimen of either PGF2alpha or PGE2 when examined for the duration of PSP diestrus. The PG treatments, however, caused a marked fall in the serum progesterone levels on days 10 and 12, although the levels in DT-bearing rats on day 10 were significantly higher than in the hysterectomized rats.
The role of the hypothalamus in the tonic secretion of prolactin induced by oestrogens in the rat.
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Effects of medial hypothalamic deafferentation on prolactin secretion in pseudopregnant rats.
Frontal hypothalamic deafferentation (FHD), which disconnects the anterior hypothalamus from the preoptic area, stops the twice daily surges of prolactin secretion of pregnancy or pseudopregnancy in the rat, and causes rapid luteolysis. Medial hypothalamic deafferentation (MHD), which separates the anterior from the posterior half of the hypothalamus, does not interrupt pregnancy and causes a significant increase in the size of the corpora lutea. To see whether MHD induces an increase in the basal level of prolactin secretion and/or a change in the pattern of prolactin surges, pseudopregnant rats were subjected to MHD or a sham operation on day 3 (day 1 = day of oestrus) and their bloods assayed for prolactin on either day 5 or days 7--8. MHD caused a specific disappearance of the day-time prolactin surge and a diminution in the height of the night-time surge, but no change from the controls in the basal prolactin level. In spite of what thus appears to be a lesser secretion of prolactin than in the controls, the corpora lutea of the MHD rats were larger, and progesterone was secreted at a higher rate and for a longer time, than in the controls. The relation of these findings to the existence of a "surge centre" in the hypothalamus was discussed.
The ultrastructure of the developing medial preoptic nucleus in the postnatal rat.
The postnatal maturation of the medial preoptic area (MPOA) of male and female rats was studied by means of light and electron microscopy. In Golgi-Kopsch preparations, bi- and multipolar cells were present at birth in both sexes; the perikarya of most of these cells, as seen with the electron microscope, exhibited an immature appearance characterized by a sparse organelle content. During the next 5-10 days, an increase in cell size and cytoplasmic differentiation occurred in each sex. By 10 days, many of the MPOA neurons displayed an increased organelle density with the most prominent change being a proliferation of rough endoplasmic reticulum. Further neuronal development was also evidenced by a greater frequency of dendritic spines than seen at either birth or 5 days. Lastly, the number of synapses per unit area increased rapidly in each sex during the first two weeks of postnatal life. Thus, a period of increasing cytological maturation and synaptic organization closely paralleled previously demonstrated stages of functional differentiation of gonadotrophin regulatory mechanisms in the rat brain.
The relation between the age of the corpus luteum (CL) and the luteolytic effect of an LH-antiserum (LH-AS): comparison of hysterectomized pseudopregnant rats with intact pregnant rats for their response to LH-AS treatment at four stages of CL activity.
At one of four stages during the period of corpus luteum (CL) activity (day 9, day 12, day 15, or day 18) groups of hysterectomized pseudopregnant (PSP) rats and of intact pregnant (PRG) rats were compared for the effect of a single sc injection of an antiserum to LH (LH-AS) on progesterone secretion. Groups of control rats were injected sc with normal horse serum (NHS) at these same stages, and in all rats, the progesterone level in jugular blood serum was measured by RIA on the day of treatment and 24 and 72 h after treatment. Among the PRG rats, the controls' progesterone levels rose to a peak on day 15, and then slowly declined. LH-AS on day 9 induced abortion and a rapid, drastic and permanent fall in the progesterone level in all rats. On day 12, it induced a similar fall in progesterone, and abortion, in 4 of 10 rats; in the 6 which remained pregnant, a much less severe fall occurred 24 h after treatment, and by 72 h the level had returned to close to the initial one. On days 15 or 18, LH-AS induced neither abortion nor a significant change in the progesterone level from that seen in the controls. Among the PSP rats, the controls' progesterone levels tended to fall progressively after day 9; the average length of diestrus was about 21 days. At each of the four stages the LH-AS induced a rapid, drastic and permanent fall in the progesterone level. Early termination of the diestrus was easily discernible in the groups injected on days 9 or 12, but was obscured in the other groups because of the similarity in length of the expected remaining diestrus and the duration of the neutralizing effect of the LH-AS on LH in the circulation. The PSP rats' CL, thus, once they become dependent on LH (about day 9), remain so to the end of PSP. The PRG rats' CL seem to lose this dependency after day 12, but the possibility could not be eliminated that the dependency may shift from LH to a placental LH-like hormone.
The role of estrogen in the regulation of luteal progesterone secretion in the rat after day 12 of pregnancy.
Pregnant rats, hypophysectomized-hysterectomized on day 12 (day 1=insemination), secreted progesterone (P) at about 50% of the day 12 level for 3-5 days. Daily treatment with estradiol 100 microng (E100) but not with E25 or E50, from day 12 to day 20, of such rats, restored P secretion until day 16 to that of intact pregnant rats; on day 17 a drastic permanent fall occurred. E100 had no effect after ovariectomy, and did not change the metabolic clearance rate of P. This E100 effect was absent in decidual tissue (DT)-bearing, or hysterectomized pseudopregnant (PSP) rats, and in pregnant ones before day 11. When pregnant rats were hypophysectomized-hysterectomized on day 10, and were treated with rat placental luteotrophin (rPL) (in the form of day 12 pregnant rat serum: "PRS-12") on days 10 and 11, however, E100 increased P secretion above that found with either PRS-12 or E100 alone. DT-bearing PSP rats, similarly operated on on day 12 and treated with PRS-12 on day 12, responded in the same way to E100. In these rats also the E100 effect lasted for four days. In the day 12 hypophysectomized-hysterectomized pregnant rat, the E100 effect could not be prolonged by single treatments with PRS-12 on either days 13, 14 or 16, but when PRS-12 was given daily from day 12 to 19, P was secreted until day 20 only slightly below the day 12 level; this treatment plus E100 raised P secretion, prolonged it to day 18, and led to a marked fall by day 20 similar to that of the intact pregnant rat at term. The marked increase in P secretion between days 12 and 15 of normal pregnancy may thus be a response to intraluteal estrogen; the pattern of P secretion from day 12 to term may reflect the effects of both estrogen and rPL. rPL probably induces this effect by generating luteal estrogen and LH receptors. The placenta may also secrete an LH-like hormone (rCG?) which, through the LH receptors, could stimulate intraluteal estrogen production.
The influence of luteinizing hormone (LH), prolactin, and the uterus on the development of a dependency on LH in the control of progesterone secretion in the pseudopregnant rat.
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The luteotrophic effect of estrogen in the rat: prevention by estradiol of the luteolytic effect of an antiserum to luteinizing hormone in the pregnant rat.
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Luteotrophic action of decidual tissue in the rat: comparison of jugular and uterine vein progesterone levels, and the effect of ligation of the utero-ovarian conncections.
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Venous outflow of the hormones secreted by the rat pituitary autotransplanted beneath the kidney capsule.
In adult female or male rats subjected to hypophysectomy and autotransplantation of the pituitary beneath the renal capsule, the levels of prolactin in the renal vein of the pituitary-bearing kidney were not significantly different from those found either in the renal vein of the contralateral kidney or in the jugular veing. LH levels were slightly but highly significantly higher than those found in hypophysectomized rats; the levels found in the two renal veins and the jugular vein were also not sigificantly different from one another.
Radioimmunologic assessment of the level of circulating LH antibodies after passive immunization of the rat: relation to the level of LH secretion.
A double antibody radioimmunologic technique was used to estimate circulating levels of "free" LH antibodies (Ab) (i.e., Ab available for binding to radioiodinated rat LH in vitro) after a single injection of an equine antiserum to bovine LH (LH-AS) into cyclic (diestrus-1), early pregnant (d 6 or d 8), short-term (1 d) or long-term (12 d) ovariectomized, or 8-d hypophysectomized female rats. In both cyclic and pregnant rats given 0.5 ml LH-AS sc the blood Ab levles peaked 1 to 2 days after injection and then decreased exponentially (half-time: 14.6-17.0 h) and equally: vaginal estrus also appeared in the cyclic and the aborting pregnant rats on the 6th day, and ovulation on the 7th day after LH-AS treatment, when the blood levels had fallen to very low values. The rate of exponential decrease in blood Ab levels was not affected by other routes of administration (iv or ip) of LH-AS, or by sc doses of 1.0 or 0.25 ml, although the peak levels and their duration were related to dose and route of administration. Ovariectomy significantly increased the rate of exponential Ab decrease (half-time: 9.8 h in rats tested 12 days after operation) and hypophysectomy markedly diminished it (half-time: 63.0 h in rats tested 8 days after operation). Daily treatment of hypophysectomized rats with 20 mu/day of ovine LH from the time of LH-AS injection increased the rate of exponential Ab decrease to one approaching that of the intact rats (half-time: 20.5 h). Free LH antibodies thus seem to disappear from the circulation at a rate proportional to the amount of LH in the circulation.
The luteotrophic action of decidual tissue: the stimulating effect of decidualization on the serum progesterone level of pseudopregnant rats.
On day 5 (4th diestrous day), pseudopregnant rats were arranged in pairs, one member of which was subjected to hysterectomy (H-ect) and the other to uterine scratching to induce formation of decidual tissue (DT). Blood samples were collected from each pair of rats immediately before and at various intervals after operation until day 13, and with very few exceptions were assayed for progesterone by CPB in the same assay. From 21 such pairs, the following findings emerged: During the period from day 7-day 11 inclusive, a DT-bearing rat's serum progesterone level was higher than that of its H-ect paired control in 79% of the paired comparisons; the mean serum progesterone level of the DT-bearing rats was higher than that of the H-ect rats on each day during this period; and the progesterone level group mean for all the DT-bearing rats during this period was at least 25% (P less than 0.05) higher than that of the H-ect rats. On days 6, 12, and 13, however, no significant differences were found between the 2 groups by any basis of comparison. Ordinary pseudopregnant rats (subjected only to 1aparotomy on day 5) and rats subjected to uterine scratching which failed to form DT had progesterone levels below or similar to, respectively, those of the H-ect members in the pairs. The findings were interpreted as evidence that DT increases the rate of progesteron secretion.