Prolactin secretory rhythm of mated rats induced by a single injection of oxytocin.
نویسندگان
چکیده
Mating or vaginocervical stimulation [copulatory stimulus (CS)] induces two daily surges of the hormone prolactin (PRL) in rats. This unique secretory pattern of PRL surges is characteristic for the first half of pregnancy and is also present in ovariectomized (OVX) rats. Studies have shown that CS additionally provokes an acute release of the hormone oxytocin (OT). In this study, we tested whether a single injection of OT (iv) is sufficient to initiate the PRL secretion pattern of OVX/CS rats. Furthermore, we measured the 24-h profile of dopamine (DA) content in the anterior lobe of the pituitary gland, because DA is the major inhibitory factor of PRL secretion. The results indicated that a single injection of OT induces a PRL secretory rhythm and a DA release pattern similar to that initiated by CS. Immunocytochemical investigation showed that particular OTergic neurons in the hypothalamus express receptors for PRL, as well as for vasoactive intestinal polypeptide, which indicates an involvement in generating the PRL rhythm and entraining it to the ambient photoperiod. On the basis of this study, we suggest that the PRL-DA inhibitory feedback loop between lactotrophs and DAergic neurons plays a crucial role in generating the oscillatory PRL secretion pattern in CS rats. A timing signal, likely provided by the hypothalamic suprachiasmatic nucleus, entrains the autonomous PRL oscillation to a particular time of day. Mathematical modeling was used to illustrate the proposed network function. The experimental results further suggest an additional feedback mechanism in which certain hypothalamic OTergic neurons are influenced by PRL.
منابع مشابه
Systemic oxytocin induces a prolactin secretory rhythm via the pelvic nerve in ovariectomized rats.
We have shown previously that an intravenous injection of oxytocin (OT) in ovariectomized (OVX) rats initiates a circadian rhythm of prolactin (PRL) secretion similar to that observed after cervical stimulation (CS). In this study, we investigated the pathway through which OT triggers the PRL rhythm. We first tested whether an intracerebroventricular injection of OT could trigger the PRL secret...
متن کاملPeripheral regulation of prolactin by oxytocin: focus on "Systemic oxytocin induces a prolactin secretory rhythm via the pelvic nerve in ovariectomized rats".
متن کامل
A mathematical model for the mating-induced prolactin rhythm of female rats.
For the first 10 days of pregnancy and the first 12 days of pseudopregnancy, the secretion of prolactin (PRL) from pituitary lactotrophs is rhythmic, with two surges/day. This rhythm can also be triggered by bolus injection of oxytocin (OT). We describe a mathematical model for the initiation, maintenance, and termination of the OT-induced PRL rhythm. In our model, the mechanism for this circad...
متن کاملOxytocin action at the lactotroph is required for prolactin surges in cervically stimulated ovariectomized rats.
Cervical stimulation induces two daily rhythmic prolactin surges, nocturnal and diurnal, which persist for several days. We have shown that a bolus injection of oxytocin initiates a similar prolactin rhythm, which persists despite low levels of oxytocin after injection. This suggests that oxytocin may trigger the cervical stimulation-induced rhythmic prolactin surges. To investigate this hypoth...
متن کاملEditorial Focus: Peripheral regulation of prolactin by oxytocin: focus on “Systemic oxytocin induces a prolactin secretory rhythm via the pelvic nerve in ovariectomized rats”
THE HORMONES PROLACTIN (PRL) and oxytocin (OT) are functionally linked to regulate processes in and beyond reproduction. Both hormones are released into the circulation in response to orgasm, mating, nursing, stress, and osmotic stimulation to regulate reproductive behavior, pregnancy, lactation, stress-related responses, and fluid and electrolyte homeostasis (3, 4, 7, 9, 10, 13). Notably, PRL ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- American journal of physiology. Endocrinology and metabolism
دوره 290 3 شماره
صفحات -
تاریخ انتشار 2006