Biomaterial Database

A "critical period" for cervically-stimulated prolactin relase. 1976

M S Smith, and J D Neill

To investigate the role of ovarian steroids in the initiation and maintenance of the prolactin surges typical of pseudopregnancy in the rat, the pattern of plasma prolactin concentrations resulting from cervical stimulation of long-term ovariectomized rats was determined. Cervical stimulation of rats, ovariectomized 2-4 weeks previously, at 1900 h (lights on 0600-1800 h) resulted in a surge of prolactin which was initiated 4-6 h later and which was similar in timing and duration to the nocturnal prolactin surge of intact, pseudopregnant rats. Daily prolactin surges continued for 6 days but declined thereafter. Because plasma progesterone levels were elevated significantly after cervical stimulation, the experiment was repeated iin adrenalectomized-ovariectomized rats. Prolactin surges were still observed, demonstrating that ovarian and adrenal steroids are required neither for initiation nor maintenance of prolactin surges after cervical stimulation. Cervical stimulation at different times of the day (1900 h, 2400 h or 0400 h) always resulted in a surge of prolactin which peaked at 0300-0700 h. The latency from cervical stimulation in the peak of the prolactin surge was 8 h for the 1900 h group, 5 h for the 2400 h group, and 3 h for the 0400 h group. Thus, the appearance of prolactin surges is related to the time of day rather than to the time cervical stimulation is applied, demonstrating the existence of a "critical period" for cervically-induced prolactin release.

UI	MeSH Term	Description	Entries
D010053	Ovary	The reproductive organ (GONADS) in female animals. In vertebrates, the ovary contains two functional parts: the OVARIAN FOLLICLE for the production of female germ cells (OOGENESIS); and the endocrine cells (GRANULOSA CELLS; THECA CELLS; and LUTEAL CELLS) for the production of ESTROGENS and PROGESTERONE.	Ovaries
D010812	Physical Stimulation	Act of eliciting a response from a person or organism through physical contact.	Stimulation, Physical,Physical Stimulations,Stimulations, Physical
D011374	Progesterone	The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS.	Pregnenedione,Progesterone, (13 alpha,17 alpha)-(+-)-Isomer,Progesterone, (17 alpha)-Isomer,Progesterone, (9 beta,10 alpha)-Isomer
D011388	Prolactin	A lactogenic hormone secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). It is a polypeptide of approximately 23 kD. Besides its major action on lactation, in some species prolactin exerts effects on reproduction, maternal behavior, fat metabolism, immunomodulation and osmoregulation. Prolactin receptors are present in the mammary gland, hypothalamus, liver, ovary, testis, and prostate.	Lactogenic Hormone, Pituitary,Mammotropic Hormone, Pituitary,Mammotropin,PRL (Prolactin),Hormone, Pituitary Lactogenic,Hormone, Pituitary Mammotropic,Pituitary Lactogenic Hormone,Pituitary Mammotropic Hormone
D011555	Pseudopregnancy	An acyclic state that resembles PREGNANCY in that there is no ovarian cycle, ESTROUS CYCLE, or MENSTRUAL CYCLE. Unlike pregnancy, there is no EMBRYO IMPLANTATION. Pseudopregnancy can be experimentally induced to form DECIDUOMA in the UTERUS.	Pseudocyesis,Pseudopregnancies
D002369	Castration	Surgical removal or artificial destruction of gonads.	Gonadectomy,Castrations,Gonadectomies
D002584	Cervix Uteri	The neck portion of the UTERUS between the lower isthmus and the VAGINA forming the cervical canal.	Cervical Canal of the Uterus,Cervical Canal, Uterine,Ectocervix,Endocervical Canal,Endocervix,External Os Cervix,External Os of the Cervix,Uterine Cervical Canal,Cervix,Cervixes,Uterine Cervix,Canal, Endocervical,Canal, Uterine Cervical,Cervix, External Os,Cervix, Uterine,Endocervical Canals,Uterine Cervical Canals
D002940	Circadian Rhythm	The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs or environmental and physiological stimuli.	Diurnal Rhythm,Nyctohemeral Rhythm,Twenty-Four Hour Rhythm,Nycthemeral Rhythm,Circadian Rhythms,Diurnal Rhythms,Nycthemeral Rhythms,Nyctohemeral Rhythms,Rhythm, Circadian,Rhythm, Diurnal,Rhythm, Nycthemeral,Rhythm, Nyctohemeral,Rhythm, Twenty-Four Hour,Rhythms, Circadian,Rhythms, Diurnal,Rhythms, Nycthemeral,Rhythms, Nyctohemeral,Rhythms, Twenty-Four Hour,Twenty Four Hour Rhythm,Twenty-Four Hour Rhythms
D005260	Female		Females
D000315	Adrenalectomy	Excision of one or both adrenal glands. (From Dorland, 28th ed)	Adrenalectomies