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SUMMARY
The efficiency of the dorso-lateral prostate (d.l.p.) of the rat to concentrate 65Zn was markedly depressed following hypophysectomy, but this glandular function could be maintained in the absence of the pituitary by the administration of suitable doses of chorionic gonadotrophin or testosterone. Removal of the testes in the hypophysectomized rat did not alter appreciably the maintenance effect of testosterone on the d.l.p.
The effects of oestradiol on the efficiency of the d.l.p. to concentrate 65Zn were diverse and involved multiple sites of action. With a dose of 0·1 μg of oestradiol there was stimulation of uptake of 65Zn, and with 1 μg a sudden depression. The latter effect was paralleled by decreased size of the gland and histological evidence of marked cell atrophy. Neither the stimulatory nor depressant effects of oestradiol on 65Zn uptake could be reproduced in hypophysectomized rats maintained on gonadotrophin, indicating that these two actions of oestrogen involved the pituitary axis.
Larger doses of oestradiol administered to hypophysectomized and hypophysectomized-castrated rats maintained on testosterone also exerted an inhibitory effect on the efficiency of the d.l.p. to concentrate 65Zn. There was maximal antagonism with an androgen: oestrogen ratio of 5:1, and as the proportion of oestrogen was increased there was a rebound rise in efficiency of the d.l.p. to take up 65Zn. The depression of 65Zn uptake by this peripheral-type of antagonism was not accompanied by depression in glandular weight. Even more striking was the observation that, in the face of this lowered glandular function, there was no evidence of any depression histologically or cytologically.
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SUMMARY
The data presented in this paper illustrate a distinct yearly cycle of activity in the capacity of the dorso-lateral prostate (d.l.p.) of the male laboratory rat to concentrate injected 65Zn. From 60 to 85% more 65Zn was taken up per mg of glandular tissue in the months of February-March and June-July than at other times of year. Studies of the corresponding weights of the d.l.p. showed trends towards lower glandular weights in January and in April; the maximum difference noted between high and low glandular weights was, however, only 28%. That this increased uptake of 65Zn by the d.l.p. in February-March and June-July was a strong inherent feature was illustrated by the fact that rats of various ages, from 8 weeks to 1½ years, showed this increased glandular activity at these times of year. Of all the animals tested only the immature rat of 5 weeks of age and the exhausted breeder did not manifest this seasonal activity.
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SUMMARY
Eleven days following hypophysectomy the capacity of the rat testis to take up administered 65Zn is markedly depressed below values noted in intact controls, even though microscopically there is only a slight diminution in the number of germinal epithelial and interstitial elements. Interstitial cell-stimulating hormone (ICSH) in doses of 5 μg./day administered from the 5th to the 10th day after operation completely prevented the fall in total 65Zn uptake of the testis following removal of the pituitary. Follicle stimulating hormone (FSH) was less effective than ICSH in this regard. The possibility of the FSH effect being due to contamination with ICSH is considered. Growth hormone and prolactin in doses of 200 μg./day administered from the 5th to 10th day after operation were ineffective in preventing the fall in 65Zn uptake of the testis following hypophysectomy.
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The ability to assay small amounts of the peptide releasing hormones in biological fluids would aid greatly in the assessment of hypothalamic function. We have recently described a specific radioimmunoassay for luteinizing hormone releasing hormone (LH-RH) (Jeffcoate, Fraser, Gunn & Holland, 1973a, b) and in this study we report a radioimmunoassay for the tripeptide, thyrotrophin releasing hormone (TRH).
Thyrotrophin releasing hormone (2 mg) was conjugated to 10 mg bovine serum albumin in borate buffer pH 9·0 by the bis-diazotized benzidene method (Bassiri & Utiger, 1972 a). After 2 h at 5 °C the mixture was dialysed against distilled water for 48 h and against 0·15 m-NaCl for 24 h. This technique conjugates TRH by the imidazole ring of histidine to the protein. A sample of conjugate (2·5 mg) in saline was homogenized with Freund's complete adjuvant and injected into 20 intradermal sites in a White New Zealand rabbit.
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ABSTRACT
By suitable immunization of mice and fusion of their spleen cells with a non-secretor mouse myeloma line, monoclonal antibodies have been produced which react with the human thyroid microsomal (M) antigen. These monoclonal antibodies showed no reactivity by enzyme-linked immunoassay with liver microsomes or thyroglobulin and their specificity was confirmed by immunolocalization studies, in which they showed the staining characteristics of human M antibodies. All four monoclonal antibodies tested were immunoglobulin M; three were cytotoxic to thyroid cell monolayers. The lack of cytotoxicity with the fourth monoclonal supports the concept that certain epitopes of the M antigen may be partially or completely absent at the thyroid cell surface. These monoclonal antibodies should permit further characterization of the thyroid M antigen in view of their absence of cross-reactivity with thyroglobulin.
J. Endocr. (1985) 105, 47–52
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The purpose of this study was to determine if luteinizing hormone releasing hormone (LH-RH) could be detected in the peripheral blood of the rat on the afternoon of pro-oestrus by the radioimmunoassay described elsewhere (Jeffcoate, Fraser, Gunn & Holland, 1973a; Jeffcoate, Fraser, Holland & Gunn, 1973b).
Female Sprague—Dawley rats, weighing 220–270 g, were maintained in a room illuminated from 05.00 to 19.00 h. The animals were observed for at least two consecutive 4-day oestrous cycles as judged by daily vaginal smears. At various times on the afternoon of pro-oestrus the animals were lightly anaesthetized with ether and rapidly desanguinated by cardiac puncture. Plasma luteinizing hormone (LH) was determined using the radioimmunoassay described by Daane & Parlow (1971) with minor modifications. This utilized purified rat LH for radio-iodination (NIAMD-Rat LH-1–3), NIAMD-Anti-Rat LH serum-1 and a rat LH preparation (NIAMD-Rat LH-RP-1) was used as standard. Serum (1–2 ml) samples were
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The decapeptide luteinizing hormone releasing factor (LH-RF) has recently been isolated, sequenced and synthesized (Schally, Arimura, Kastin, Matsuo, Baba, Redding, Nair, Debeljuk & White, 1971). This has made possible the development of radioimmunoassays for this factor enabling it to be measured in biological fluids in vivo and in vitro.
Two milligrammes of the synthetic decapeptide (Hoechst) were conjugated to 2 mg bovine serum albumin (BSA) using 75 mg 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide in 0·25 ml water (Goodfriend, Levine & Fasman, 1964). After dialysis overnight, 1 mg of the conjugate in 2 ml water, emulsified in Freund's complete adjuvant, was injected into 20 intradermal sites in a white New Zealand rabbit. A blood sample was obtained 8 weeks after this primary immunization and the assay developed using this antiserum.
LH-RF (0·1–1 μg) was iodinated with 125I (0·5–1 mCi) by the chloramine-T technique (5 μg of chloramine-T), specific activities between 100 and 500 μCi/μg being obtained.
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SUMMARY
Luteinizing hormone releasing hormone (LH-RH) was detected in hypothalamic extracts of rats, rabbits and chickens using a radioimmunoassay for synthetic LH-RH decapeptide. The mobilities of the immunologically active fraction and of synthetic LH-RH were the same in various chromatographic systems (gel filtration on Sephadex, thin-layer chromatography on silica gel and ion-exchange chromatography on carboxymethylcellulose) suggesting that mammalian, avian and synthetic LH-RH's are closely related.
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SUMMARY
Autoimmunity to luteinizing hormone releasing hormone (LH-RH) in adult male rats, induced by immunization with LH-RH conjugated to bovine serum albumin, resulted in atrophy of the testes and secondary sex organs and aspermatogenesis. Both immunoreactive luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in serum and the pituitary were reduced to low levels compared with those of control animals. It is suggested that antibodies to LH-RH can inhibit the action of endogenous hormone and that LH-RH is, in fact, the gonadotrophin-releasing hormone in the rat, required for the release of both LH and FSH.
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*Department of Surgery, University of Dundee, Dundee, DD1 4HN and †Department of Chemical Pathology, St Thomas's Hospital, London, SE1 7EH
(Received 23 August 1974)
Short-term inhibition of luteinizing hormone releasing hormone (LH-RH) in vivo can be conveniently studied by injection of antisera (Fraser & Gunn, 1973), and in the ovariectomized rat this was found to reduce both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels when measured 7 and 24 h after injection (Koch, Chobsieng, Zor, Fridkin & Lindner, 1973). Long-term inhibition of LH-RH cannot be satisfactorily achieved by injection of antisera but is induced by active immunization. In a previous study we have shown in the male rat that this results in low levels of LH and FSH in serum and pituitary, suggesting that LH-RH is required for synthesis as well as release of both LH and FSH (Fraser, Gunn, Jeffcoate & Holland, 1974). In this study, the work
