Gonadotrophin‐releasing activity of the median eminence at different ages

Campbell, H. J.; Gallardo, Eduard

doi:10.1113/jphysiol.1966.sp008062

Cited by 18 publications

(7 citation statements)

References 7 publications

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“…This should then attest to the high receptivity of the immature pituitary to its regulatory neurohormone, and to the active ness of the neurohormone itself. Campbell and G allardo (1966) were able to show that the median eminence of the new-born rat contains active LHRF material, as evidenced by the ability of such extracts to induce ovulation in the rabbit upon intrapituitary infusion. The results of the present investigation complement those of these two authors, which demonstrate that, in addition to LHRF, the SME of the new born contains active FSHRF material.…”

Section: Discussionmentioning

confidence: 90%

Changes in Concentration of Female Rat Pituitary FSH and Stalk-Median Eminence Follicle Stimulating Hormone Releasing Factor with Age

Corbin¹,

Daniels²

1967

Neuroendocrinology

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Section: Discussionmentioning

confidence: 90%

Changes in Concentration of Female Rat Pituitary FSH and Stalk-Median Eminence Follicle Stimulating Hormone Releasing Factor with Age

Corbin¹,

Daniels²

1967

Neuroendocrinology

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“…The hypothalamo-hypophysial portal system is present and functional in the first few days of life (Glydon, 1957;Florsheim & Rudko, 1968) while gonadotrophin releasing hormone activity is present in the median eminence very early in postnatal development (Campbell & Gallardo, 1966; Araki, Toran-Allerand, Ferin & Vande Wiele, 1975). Furthermore, neonatal ovariectomy results in significantly increased levels ofLH by 10 days of age (Caligaris et al 1972), thereby suggest¬ ing that the tonic release of gonadotrophins, as regulated by ovarian steroids, is functional early in life.…”

Section: Discussionmentioning

confidence: 99%

Ontogeny of Prolactin and Luteinizing Hormone Responses to Oestrogen and Progesterone in Immature Rats

Puig-Duran¹,

Mackinnon²

1978

Journal of Endocrinology

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Female Wistar rats aged 21, 18 and 16 days were injected s.c. with oestradiol benzoate (OB) at 12.00 h on Day 1 and the concentrations of LH and prolactin in the serum were measured 54 h later at 18.00 h on Day 3; the effect of a second injection of OB, given at different intervals after the first, on the concentration of gonadotrophins in the serum was also investigated. In 21-day-old rats, surges of both LH and prolactin occurred at 18.00 h on Day 3; if a second dose of OB was given within 24 h of the first, then the expected surge of LH was diminished, but if it was given on the morning of Day 3 the surge was augmented. The concentration of prolactin was, however, unaffected by the second injection. In 18-day-old rats there were no surges of gonadotrophin in response to a single OB stimulus on Day 1; however, a second dose of OB given on the morning of either Day 2 or 3 caused surges of both LH and prolactin at 18.00 h on Day 3. No such response was obtainable in 16-day-old rats. 1 with diethylstilboestrol or another synthetic oestrogen (RU2858). The results obtained paralleled data from the previous experiment in which progesterone was given after priming with the natural steroid OB.Although the capacity for cyclicity or acyclicity in rats is normally determined early in the neonatal period, these results suggest that mechanisms concerned with the surge response to a single OB stimulus are intact and functional by 21 days of age but not in younger rats; however, it is possible to facilitate both the LH and prolactin response as early as 14 days of age.

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“…A study of the development of the primary plexus in the rabbit (Campbell, 1965b) has revealed that this structure begins to form at about the 21st day of gestation and is well-developed in the new-born rabbit. Further the luteinizing hormone-releasing factor known to be present in the adult rabbit median eminence (Campbell et al 1964) has been found to occur also in the median eminence of the new-born rabbit (Campbell & Gallardo, 1965).…”

Section: Resultsmentioning

confidence: 99%

“…The rabbit was chosen as such a species. A preliminary account of this work has already been presented (Campbell, 1965 a). …”

mentioning

confidence: 99%

Effects of neonatal injections of hormones on sexual behaviour and reproduction in the rabbit.

Campbell¹

1965

The Journal of Physiology

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Permanent sterility and absence of sexual behaviour results from the neonatal injection of androgenic (Pfeiffer, 1936;Barraclough, 1961) and oestrogenic (Takasugi, 1952;Noumura, 1958) (McCann, Taleisnik & Friedman, 1960) is also present in these sterile animals. Moreover, the anterior pituitary glands of such sterile rats contain luteinizing hormone (Gorski & Barraclough, 1961), so that it seemed possible that neonatal steroid treatment in the female rat might act upon the neurogenic timing mechanism that regulates the release of LRF and hence of LH.It appeared of interest, therefore, to examine the effects of neonatal treatment with various hormones in a species possessing LRF (Campbell, Feuer & Harris, 1964) but lacking the neurogenic timing mechanism. The rabbit was chosen as such a species. A preliminary account of this work has already been presented (Campbell, 1965 a). METHODSThe sixty-one animals used were bred in the Department. All rabbits were maintained on a pellet diet (M.R.C. Diet No. 81) with occasional bread, vegetable and milk supplements. Tap water was supplied ad libitum. The litters were allocated at random to experimental (hormone) and control (arachis oil) injections. On the second or third day from birth each of the young in the litters was injected by passing a fine hypodermic needle (0 40 x 30 mm) under the skin of the back from a point near the tail to a point near the shoulder. After injection, the needle was quickly withdrawn and the animal examined for

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Gonadotrophin‐releasing activity of the median eminence at different ages

Cited by 18 publications

References 7 publications

Changes in Concentration of Female Rat Pituitary FSH and Stalk-Median Eminence Follicle Stimulating Hormone Releasing Factor with Age

Changes in Concentration of Female Rat Pituitary FSH and Stalk-Median Eminence Follicle Stimulating Hormone Releasing Factor with Age

Ontogeny of Prolactin and Luteinizing Hormone Responses to Oestrogen and Progesterone in Immature Rats

Effects of neonatal injections of hormones on sexual behaviour and reproduction in the rabbit.

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