The development of the hypothalamo–pituitary axis in the neonatal rat: sexual maturation in male and female rats as assessed by hypothalamic LHRH and pituitary and serum LH and FSH concentrations

1977 ◽  
Vol 55 (5) ◽  
pp. 1091-1097 ◽  
Author(s):  
J. H. Dussault ◽  
P. Walker ◽  
J. D. Dubois ◽  
F. Labrie
Keyword(s):  
Developmental Process ◽  
Neonatal Period ◽  
Neonatal Rat ◽  
Female Rats ◽  
Human Foetus ◽  
Marked Rise ◽  
Male And Female Rats ◽  
Specific Radioimmunoassay ◽  
Serum Lh ◽  
And Control

Using specific radioimmunoassay techniques, we have measured hypothalamic LHRH concentration and pituitary and serum LH and FSH concentrations in neonatal rats from 0 to 60 days after birth. There were no sex differences demonstrable for hypothalamic LHRH concentration, which rose from minimal values at 2 days to peak concentrations at 22–28 days and declined significantly with the approach of puberty. Pituitary LH concentration in the two sexes rose to peak values at 19–25 days, with significantly higher values observed in females (p < 0.01). Serum LH concentration was high in both sexes at birth, the values in females being significantly higher than those observed in males (p < 0.01). While the serum LH concentration remained relatively stable throughout the study period in males, it declined rapidly to a nadir at 28 days in females. Pituitary FSH concentration was low at birth in both sexes. Females demonstrated a marked rise to peak concentrations at 16 days while males achieved significantly lower peak prepuberal values (p < 0.01) at 28 days. Serum FSH concentration was significantly higher in females (p < 0.01) at birth and rose further to peak values at 16 days. Males attained peak serum FSH concentrations at 35 days. These data demonstrate that the maturation of the hypothalamo–pituitary–gonadal axis develops in the neonatal period in the rat and confirm the presence of significant differences in hypothalamic sexual differentiation and control. The possibility of this developmental process in the neonatal rat as a model for the study of the midgestational hypothalamic maturation of the human foetus is discussed.

Selected Contribution: Estrogen receptor-α antisense decreases brain estrogen receptor levels and affects ventilation in male and female rats

2001 ◽  
Vol 91 (4) ◽  
pp. 1886-1892 ◽  
Author(s):  
Shashita R. Inamdar ◽  
Kathleen M. Eyster ◽  
Evelyn H. Schlenker
Keyword(s):  
Estrogen Receptor ◽  
Aspartic Acid ◽  
Estrogen Receptor Α ◽  
Neonatal Rat ◽  
Female Rats ◽  
Antisense Oligodeoxynucleotide ◽  
Protein Levels ◽  
Ventilatory Responses ◽  
Rat Pups ◽  
Male And Female Rats

We hypothesized that administration of an antisense oligodeoxynucleotide (ODN) to estrogen receptor (ER)-α mRNA decreases the ER protein in the neonatal rat brain, alters the sex-specific ventilatory responses to aspartic acid in rats, and counteracts the effects of testosterone proportionate (TP) in females. One-day-old rat pups were injected intraventricularly with vehicle, antisense ER ODN, or scrambled ODN control. Additional groups of females received TP or vehicle and one of the three treatments. Brain ER protein levels were decreased by 65% at 6 h and 35% at 24 h after antisense ODN. Aspartic acid decreased ventilation in all groups of weanling males and females except ER ODN-treated females and TP-vehicle-treated females. Aspartic acid decreased ventilation in all groups of adult females except those given TP and in males. Weanling ER ODN-treated rats were shorter and weighed less than controls. Only adult ER ODN-treated males exhibited these traits. Thus neonatal ER affects aspartic acid modulation of breathing and body growth in a sex-specific and developmental manner.

PREVENTION OF CENTRAL DEFEMINIZATION BUT NOT MASCULINIZATION IN MALE RATS BY INHIBITION NEONATALLY OF OESTROGEN BIOSYNTHESIS

1977 ◽  
Vol 74 (3) ◽  
pp. 375-382 ◽  
Author(s):  
J. T. M. VREEBURG ◽  
PAULA D. M. VAN DER VAART ◽  
P. VAN DER SCHOOT
Keyword(s):  
Sexual Function ◽  
Ovarian Function ◽  
Testosterone Propionate ◽  
Neonatal Period ◽  
Female Rats ◽  
Male Rats ◽  
Normal Male ◽  
Male And Female ◽  
Male And Female Rats ◽  
Copulatory Behaviour

SUMMARY An inhibitor of aromatization, androsta-1,4,6-triene-3,17-dione (ATD), was administered to newborn male and female rats and various parameters of gonadal and sexual function were examined in adulthood. Males injected with 1 mg ATD on the day of birth (day 1) and on days 3, 5, 10 and 15 postnatally, subsequently (day 55) showed normal male and female copulatory behaviour, but were not able to maintain cyclicity in ovarian transplants. When the ATD was administered by Silastic implants, however, cyclicity in ovarian transplants did occur. Neither form of treatment brought about significant changes in neonatal plasma or testicular testosterone concentrations. Female rats implanted on day 3 of life with Silastic capsules containing ATD and then given an injection of 0·25 mg testosterone propionate on day 5 subsequently showed normal ovarian function, whereas the controls receiving only testosterone propionate showed persistent vaginal cornification, anovulation and polyfollicular ovaries. The results support the view that the central conversion of testicular androgens to oestrogens during the neonatal period is necessary to abolish cyclic gonadotrophin release and to suppress female copulatory behaviour.

EFFECT OF SYNTHETIC THYROTROPHIN RELEASING FACTOR ON PROLACTIN AND LUTEINIZING HORMONE SECRETION IN MALE AND FEMALE RATS DURING VARIOUS REPRODUCTIVE STATES

1975 ◽  
Vol 67 (3) ◽  
pp. 425-430 ◽  
Author(s):  
R. P. DEIS ◽  
NIA ALONSO
Keyword(s):  
Hormone Secretion ◽  
Female Rats ◽  
Male Rats ◽  
Serum Prolactin ◽  
Serum Prolactin Level ◽  
Luteinizing Hormone Secretion ◽  
Male And Female Rats ◽  
Serum Lh ◽  
The Mean ◽  
Lh Secretion

SUMMARY The effect of synthetic thyrotrophin releasing factor (TRF) on serum prolactin and LH concentrations was determined by radioimmunoassay in male, cyclic and pseudopregnant female rats. A solution of TRF (0·1, 0·25, 0·5 and 1 μg/rat) was injected i.v. at 17.00 h into rats pretreated with sodium pentobarbitone at 13.00 h. A group of male rats was also treated with TRF at 11.00 h after pretreatment with sodium pentobarbitone at 07.00 h. Fifteen minutes after TRF administration, blood samples were obtained by heart puncture. Doses of 0·25, 0·5 and 1 μg TRF significantly increased the serum prolactin concentration in pro-oestrous rats. The mean serum prolactin level after the injection of 0·5 and 1 μg into oestrous rats and 0·5 μg TRF into dioestrous day 2 rats, was significantly greater than the control values. Injection of TRF on day 1 of dioestrus had no effect. Serum LH concentration was not significantly modified by the various doses of TRF administered. On day 3 of pseudopregnancy a significant increase of serum prolactin values was obtained with 0·5 and 1 μg TRF. On day 7 of pseudopregnancy a dose of 0·5 μg produced the same effect, but on day 10 of pseudopregnancy only 1 μg TRF significantly increased serum prolactin levels when compared with the control rats. In male rats serum prolactin concentration was significantly greater than the control values after TRF treatment either in the morning or the afternoon. The response was similar to that obtained in pro-oestrous rats. The results suggest that the ability of synthetic TRF to stimulate prolactin release exists in both female and male rats and that TRF does not affect LH secretion.

CIRCADIAN FLUCTUATIONS OF SERUM HORMONE LEVELS IN PREPUBERTAL MALE AND FEMALE RATS

1976 ◽  
Vol 83 (2) ◽  
pp. 269-279 ◽  
Author(s):  
K. D. Döhler ◽  
W. Wuttke
Keyword(s):  
Age Groups ◽  
Serum Testosterone ◽  
Female Rats ◽  
Serum Prolactin ◽  
Male And Female ◽  
Hormone Levels ◽  
Male And Female Rats ◽  
Serum Lh ◽  
Serum Hormone ◽  
Old Females

ABSTRACT Diurnal variations in serum hormone levels during 2 different stages of prepubertal development were investigated in male and female rats. Groups of 13 to 18 and 25 to 30 day old male and female rats were decapitated at 4-hour by intervals during a period of 24 h. Their blood was collected and hormones were measured by radio-immunoassay. FSH levels were constantly high in 13 to 18, but low in 25 to 30 day old females. FSH was low in younger males, and significantly higher but without diurnal fluctuations in the older males. Serum LH was low in approximately 40% of the 13 to 18 day old females, while 40% had moderately high levels, and the remaining females extremely high levels of the hormone. Most of the extremely high LH peaks were found at 15.00 h and some at 03.00 h. Older females and males of both age groups had constantly low serum LH levels. Serum oestradiol was high in males and females during days 13 to 18, but it was lower in the 25 to 30 day old animals. In the young females prolactin was slightly elevated between 15.00 h and 19.00 h, while in the males the serum prolactin fluctuations were not significant. Serum testosterone was low in females at all times. The 13 to 18 day old males had higher testosterone levels than the 25 to 30 day old males. Both groups showed slight, but insignificant fluctuations in serum testosterone. These results confirm result published previously and furthermore they demonstrate the existence of circasemedian or circadian rhythms for both the gonadotrophins and gonadal steroids. These results, also suggest that the maturation of the positive feedback action of oestradiol on gonadotrophin release in female rats occurs between day 10 and 20.

The development of the hypothalamo–pituitary axis in the neonatal rat: pituitary and serum prolactin concentrations

1977 ◽  
Vol 55 (1) ◽  
pp. 84-89 ◽  
Author(s):  
J. H. Dussault ◽  
P. Walker ◽  
J. D. Dubois
Keyword(s):  
Sex Differences ◽  
Developmental Process ◽  
Neonatal Period ◽  
Neonatal Rat ◽  
Serum Prolactin ◽  
Neonatal Rats ◽  
Rat Pituitary ◽  
Hypothalamic Control ◽  
Relationship Of ◽  
The Relationship

Using highly specific double-antibody radioimmunoassay techniques, we have measured pituitary and serum prolactin (PRL) concentrations in neonatal rats from birth to 60 d. Pituitary PRL concentration was low at birth in both sexes and peak prepuberal values were attained at 25–28 d. Following this time, pituitary PRL concentrations in females were significantly higher than those observed in males (p < 0.01). Serum PRL concentrations were low at birth in both sexes and remained low until 15 d, when they rose to peak values just before puberty. There were no significant sex differences with respect to serum PRL concentrations. These data indicate that hypothalamic control of PRL secretion develops during the neonatal period of the rat. The relationship of this developmental process in the neonatal rat as a possible model for the study of the midgestational hypothalamic maturation of the human fetus is discussed.

Ontogeny of sex differences in LH and FSH levels 48 h after castration in the rat

1981 ◽  
Vol 241 (6) ◽  
pp. E460-E464
Author(s):  
J. R. Lorenzen ◽  
J. A. Ramaley
Keyword(s):  
Follicle Stimulating Hormone ◽  
Female Rats ◽  
Hormonal Changes ◽  
Vaginal Opening ◽  
Immature Female ◽  
Immature Male ◽  
Male And Female Rats ◽  
Serum Lh ◽  
Pituitary Secretion ◽  
Serum Gonadotropin

Serum gonadotropin levels were measured 12, 24, and 48 h after gonadectomy in male and female rats (ages, 22--60 days) to assess when during development the rate of rise of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) after castration approximates that seen in the gonadectomized adult. In females serum LH levels 48 h after ovariectomy were increased above sham levels only when the ovaries were removed prior to vaginal opening. Ovariectomy on the day of vaginal opening or at older ages resulted in no increase in LH levels by 48 h after surgery. Serum FSH levels at 24 and 48 h after ovariectomy declined with increasing age at the time of ovariectomy. In males serum LH levels at 48 h after castration increased with increasing age at the time of gonadectomy. Serum FSH levels at either 12, 24, or 48 h after orchidectomy did not change appreciably with age at the time of surgery. It is concluded that the acute pituitary secretion of gonadotropins after removal of testes in the immature male resembles that seen in the mature male early in the course of the development of sexual maturity. In contrast, the acute pituitary secretion of gonadotropins after removal of the ovaries in the immature female does not resemble that seen in the ovariectomized adult until she is mature and capable of ovulating. Thus, the observed delay in the rise of LH seen in ovariectomized adults may be a function of some aspect of the hormonal changes associated with the estrous cycle.

A FEMALE-LIKE RISE IN LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE AFTER GONADECTOMY IN MALE RATS INDUCED BY OESTRADIOL PRETREATMENT

1979 ◽  
Vol 80 (1) ◽  
pp. 111-116 ◽  
Author(s):  
S. N. JUSTO ◽  
A. NEGRO-VILAR
Keyword(s):  
Sexual Difference ◽  
Female Rats ◽  
Male Rats ◽  
Ovariectomized Rats ◽  
Serum Concentrations ◽  
Control Male ◽  
Male And Female Rats ◽  
Series Of Experiments ◽  
And Control ◽  
Intact Rats

A marked sexual difference in the rise of serum gonadotrophin concentrations after gonadectomy has been described in the rat. Gonadectomy in males induced a rapid rise in the concentrations of both LH and FSH within 8 to 12 h, whereas ovariectomy invoked a rapid increase in the concentration of FSH while the response by LH was delayed for several days. To determine whether these differences could be explained, at least in part, by the different steroid milieu at the time of gonadectomy, a series of experiments were performed to analyse the rise in both LH and FSH serum concentrations in control male and female rats and in male rats that had been pretreated with oestradiol-17β. Adult male rats received an s.c. implant of a silicone elastomer capsule filled with crystalline oestradiol-17 β. Controls received empty capsules. Twenty-four hours later, the oestradiol-implanted rats were castrated and control animals were sham-operated. Both LH and FSH levels remained within control levels after castration in the oestradiol-implanted rats, indicating that the oestradiol implant was preventing any rise of either gonadotrophin. On day 5 after implantation, the capsules were removed, sham-implanted animals were castrated and LH and FSH levels at 12, 24, 48 and 72 h were measured and compared with those of ovariectomized rats at similar intervals. The control male rats displayed the pattern of gonadotrophin increments normally found after castration, with both LH and FSH concentrations rising significantly by 12 h after castration and with further increments at later periods. Oestradiol-treated rats showed a female-like gonadotrophin pattern. FSH levels started to rise significantly at 24 h compared with values from intact rats and increased further at 48 and 72 h. During the first 48 h, FSH levels in both oestradiol-treated, castrated rats and female gonadectomized rats were significantly lower than in castrated animals. LH levels, on the other hand, remained low in both groups during the first 48 h, starting to rise significantly above control levels by 72 h. These results indicate that the different pattern of response to gonadectomy in rats of both sexes may be altered by changes in steroid environment and, therefore, may not be genetically predetermined.

Response of rat selenoprotein P to selenium administration and fate of its selenium

1991 ◽  
Vol 261 (1) ◽  
pp. E26-E30 ◽  
Author(s):  
R. F. Burk ◽  
K. E. Hill ◽  
R. Read ◽  
T. Bellew
Keyword(s):  
Glutathione Peroxidase ◽  
Peroxidase Activity ◽  
Selenium Deficiency ◽  
Rat Plasma ◽  
Female Rats ◽  
Selenoprotein P ◽  
Glutathione Peroxidase Activity ◽  
Uptake Mechanism ◽  
Male And Female Rats ◽  
And Control

Selenoprotein P is a glycoprotein that contains greater than 60% of the selenium in rat plasma. Physiological experiments were undertaken to gain insight into selenoprotein P function. Selenium-deficient rats were injected with doses of selenium ranging from 25 to 200 micrograms/kg, and the appearance of selenoprotein P was compared with the appearance of glutathione peroxidase activity in plasma and in liver. Selenoprotein P concentration increased to 35% of control by 6 h, whereas glutathione peroxidase activity increased minimally or not at all. Moreover, in rats given 100 and 200 micrograms selenium/kg, selenoprotein P reached 75% of its concentration in control rats at 24 h, whereas glutathione peroxidase activity reached only 6% of control. Cycloheximide pretreatment blocked the appearance of selenoprotein P in response to selenium injection. Male and female rats had similar concentrations of selenoprotein P. Partially purified selenoprotein P and plasma glutathione peroxidase labeled with 75Se were administered intravenously to selenium-deficient and control rats. 75Se given as selenoprotein P disappeared more rapidly from plasma than did 75Se given as glutathione peroxidase. Selenium deficiency did not significantly affect 75Se disappearance from plasma. At 2 h, brain, but not other tissues, took up more 75Se in selenium-deficient rats than in control rats when 75Se was given as selenoprotein P. This suggests that brain has a specific uptake mechanism for selenium given in the form of selenoprotein P. These results demonstrate that several physiological properties distinguish selenoprotein P from glutathione peroxidase. However, they do not clearly indicate its function.

Gonad-gonadotrope interactions: plasma gonadotrophin levels and tumour induction in long-term castrated rats

1981 ◽  
Vol 97 (2) ◽  
pp. 181-185 ◽  
Author(s):  
Daniel M. Linkie ◽  
Jacob Furth ◽  
Diane Kourelakos
Keyword(s):  
Immunohistochemical Localization ◽  
Female Rats ◽  
Male And Female ◽  
Tumour Induction ◽  
Male And Female Rats ◽  
Specific Radioimmunoassay ◽  
Gonadotrophin Secretion ◽  
Males And Females

Abstract. The patterns of gonadotrophin secretion in intact controls and in male and female rats castrated for up to 36 months were established utilizing specific radioimmunoassay methods. Plasma LH increased 14– 16-fold and FSH rose 4–8-fold in rats of either sex in the first 30 days following gonadectomy. The subsequent 30 day interval showed an additional 76% increase of LH in both sexes and increases in FSH of 32 and 61% in males and females, respectively. These levels were maintained for an additional 34 months. The number of hypophyseal gonadotrophin containing cells, studied by immunohistochemical localization techniques, increased following gonad removal in a pattern similar to that for the circulating hormones. Development of gonadotrophin secreting tumours did not correlate with plasma gonadotrophin concentrations which suggests that the gonadotropes are uniquely resistant to tumourogenesis unlike mammotropes, thyrotropes, and corticotropes.

scholarly journals NOCICEPTIVE STIMULUS IN THE NEONATAL PERIOD AFFECTS SATELLITE GLIAL CELLS MORPHOLOGY IN ADULT LIFE, WITH DIFFERENCES BETWEEN MALE AND FEMALE RATS

2018 ◽  
Vol 32 (S1) ◽  
Author(s):  
Ana Leda Bertoncini Simoes ◽  
Greice Anne Rodrigues Silva ◽  
Carolina Giorgetto ◽  
Elisabete Cassia Carmo ◽  
Valeria Paula Sassoli Fazan
Keyword(s):  
Glial Cells ◽  
Neonatal Period ◽  
Adult Life ◽  
Female Rats ◽  
Satellite Glial Cells ◽  
Male And Female ◽  
Male And Female Rats ◽  
Nociceptive Stimulus
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