Oxytocin is required for nursing but is not essential for parturition or reproductive behavior.

Oxytocin, a neurohypophyseal hormone, has been traditionally considered essential for mammalian reproduction. In addition to uterine contractions during labor and milk ejection during nursing, oxytocin has been implicated in anterior pituitary function, paracrine effects in the testis and ovary and the neural control of maternal and sexual behaviors. To determine the essential role(s) of oxytocin in mammalian reproductive function, mice deficient in oxytocin have been generated using embryonic stem cell technology. A deletion of exon 1 encoding the oxytocin peptide was generated in embryonic stem cells at a high frequency and was successfully transmitted in the germ line. Southern blot analysis of genomic DNA from homozygote offspring and in situ hybridization with an exonic probe 3' of the deletion failed to detect any oxytocin or neurophysin sequences, respectively, confirming that the mutation was a null mutation. Mice lacking oxytocin are both viable and fertile. Males do not have any reproductive behavioral or functional defects in the absence of oxytocin. Similarly, females lacking oxytocin have no obvious deficits in fertility or reproduction, including gestation and parturition. However, although oxytocin-deficient females demonstrate normal maternal behavior, all offspring die shortly after birth because of the dam's inability to nurse. Postpartum injections of oxytocin to the oxytocin deficient mothers restore milk ejection and rescue the offspring. Thus, despite the multiple reproductive activities that have been attributed to oxytocin, oxytocin plays an essential role only in milk ejection in the mouse.

Oxytocin mediates atrial natriuretic peptide release and natriuresis after volume expansion in the rat.

Our previous studies have shown that stimulation of the anterior ventral third ventricular region increases atrial natriuretic peptide (ANP) release, whereas lesions of this structure, the median eminence, or removal of the neural lobe of the pituitary block ANP release induced by blood volume expansion (BVE). These results indicate that participation of the central nervous system is crucial in these responses, possibly through mediation by neurohypophysial hormones. In the present research we investigated the possible role of oxytocin, one of the two principal neurohypophysial hormones, in the mediation of ANP release. Oxytocin (1-10 nmol) injected i.p. caused significant, dose-dependent increases in urinary osmolality, natriuresis, and kaliuresis. A delayed antidiuretic effect was also observed. Plasma ANP concentrations increased nearly 4-fold (P < 0.01) 20 min after i.p. oxytocin (10 nmol), but there was no change in plasma ANP values in control rats. When oxytocin (1 or 10 nmol) was injected i.v., it also induced a dose-related increase in plasma ANP at 5 min (P < 0.001). BVE by intra-atrial injection of isotonic saline induced a rapid (5 min postinjection) increase in plasma oxytocin and ANP concentrations and a concomitant decrease in plasma arginine vasopressin concentration. Results were similar with hypertonic volume expansion, except that this induced a transient (5 min) increase in plasma arginine vasopressin. The findings are consistent with the hypothesis that baroreceptor activation of the central nervous system by BVE stimulates the release of oxytocin from the neurohypophysis. This oxytocin then circulates to the right atrium to induce release of ANP, which circulates to the kidney and induces natriuresis and diuresis, which restore body fluid volume to normal levels.

Populiarnaia istoriia Rossiǐ ot nachala do nashikh dneǐ ...

Mode of access: Internet.

Boḥen Tsadiḳ, bo muva deʻot ʻal ha-sefer Megilah temirin ...

Photocopy. Chicago : University of Chicago Library, Photoduplication Dept., 1986.

Gospoda nashego Iisusa Khrista svi︠a︡toe evangelīe ot Matvei︠a︡, Marka, Luki i Ioanna.

In Church Slavic.

Sefer Ḥaye adam : bo niḳbetsu u-vaʾu be-seder nakhon kol ha-mitsṿot asher yaʻaseh otam ha-adam kol yeme ḥeldo /

Includes the commentary Nishmat Adam.

Mikra ot gedolot : im 32 perushim

Title also in Russian.

Menaḥem ha-Bavli : emunot ṿe-deʻot ha-minim.

Mode of access: Internet.

Ner mitzvoh : ...beʾur le-divre ha-Rambam be-Sefer ha-mitsṿot uve-Mishneh Torah...

No more published.

Sefer Ohel Yitsḥaḳ = Ohel Jitzchak : kolel kol dine sheḥiṭot u-vediḳot ke-fi asher sidram Yaʻaḳov Ṿail, uve-tosefet merubah u-seviv lo Leḳiṭat Yitsḥaḳ ṿe-Zivḥe tamim /

Mode of access: Internet.

Ot Ioanna svi︠a︡toe blagovi︠e︡stvovanie.

Title and text in Church Slavic.

Kīevskīĭ sẏnopsis ili kratkoe sobranīe ot razlichnykh li︠e︡topist︠s︡ov o nachali︠e︡ slavenorossīĭskago naroda i pervonachalʹnykh kni︠a︡zekh bogospasaemago grada Kīeva...

Mode of access: Internet.

Gore ot uma : komedīi︠a︡ v chetyrekh di︠e︡ĭstvīi︠a︡kh v stikhakh A.S. Griboi︠e︡dova /

Mode of access: Internet.