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Growth rate and secretion of pituitary hormones in relation to age and chronic treatment with thyrotropin-releasing hormone in prepubertal dairy heifers.
Endocrinology 1977; 100(5):1394-402E

Abstract

Holstein heifers were treated with synthetic thyrotropin-releasing hormone (TRH) or saline twice daily from one week through 6 mo of age. Plasma concentrations of prolactin (PRL) and thyrotropin (TSH) were elevated (P less than .01) within 30 min after the first TRH injection (1 week of age). At 1 and 3 mo of treatment, PRL and TSH increased in response to TRH, although the TSH response was reduced (P less than .01) as compared to the first day of treatment. Although plasma growth hormone (GH) appeared to be elevated following the first TRH injection, this effect was not statistically significant (P less than .05), nor was it significantly influenced by treatment following subsequent TRH injections. None of the 3 hormones, PRL, TSH or GH, was elevated following the final TRH injection at 6 mo of age. In contrast, plasma concentrations of PRL and TSH were increased in a control heifer injected with TRH at 6 mo. These data indicate that hormonal responsiveness to TRH stimulation decreases with continued twice daily treatment at doses of TRH used in the present studies. Examination of weight gains indicated that chronic treatment with TRH was associated with increased growth rate through 6 mo of age (10.6% increased average daily gains P less than .10), which was exhibited in a steeper slope (P less than .05) of the growth curve in the TRH group. Feed intake was slightly greater in TRH heifers, although feed efficiency (kg feed/kg gain) was not different between the two groups. Plasma concentrations of PRL increased (P less than .01) with age (r = +0.938) in control heifers while plasma TSH and GH were not significantly related to age. This observation establishes a positive correlative relationship between PRL secretion and the approach of puberty in the dairly heirfer. It was also noted that elevation of PRL secretion by TRH treatment was associated with significant advancement of age at first observed estrus (9.4 vs. - 10.5 mo) suggesting that a functional relationship between PRL secretion and puberty may exist in dairy heifers.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

191244

Citation

Davis, S L., et al. "Growth Rate and Secretion of Pituitary Hormones in Relation to Age and Chronic Treatment With Thyrotropin-releasing Hormone in Prepubertal Dairy Heifers." Endocrinology, vol. 100, no. 5, 1977, pp. 1394-402.
Davis SL, Sasser RG, Thacker DL, et al. Growth rate and secretion of pituitary hormones in relation to age and chronic treatment with thyrotropin-releasing hormone in prepubertal dairy heifers. Endocrinology. 1977;100(5):1394-402.
Davis, S. L., Sasser, R. G., Thacker, D. L., & Ross, R. H. (1977). Growth rate and secretion of pituitary hormones in relation to age and chronic treatment with thyrotropin-releasing hormone in prepubertal dairy heifers. Endocrinology, 100(5), pp. 1394-402.
Davis SL, et al. Growth Rate and Secretion of Pituitary Hormones in Relation to Age and Chronic Treatment With Thyrotropin-releasing Hormone in Prepubertal Dairy Heifers. Endocrinology. 1977;100(5):1394-402. PubMed PMID: 191244.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Growth rate and secretion of pituitary hormones in relation to age and chronic treatment with thyrotropin-releasing hormone in prepubertal dairy heifers. AU - Davis,S L, AU - Sasser,R G, AU - Thacker,D L, AU - Ross,R H, PY - 1977/5/1/pubmed PY - 1977/5/1/medline PY - 1977/5/1/entrez SP - 1394 EP - 402 JF - Endocrinology JO - Endocrinology VL - 100 IS - 5 N2 - Holstein heifers were treated with synthetic thyrotropin-releasing hormone (TRH) or saline twice daily from one week through 6 mo of age. Plasma concentrations of prolactin (PRL) and thyrotropin (TSH) were elevated (P less than .01) within 30 min after the first TRH injection (1 week of age). At 1 and 3 mo of treatment, PRL and TSH increased in response to TRH, although the TSH response was reduced (P less than .01) as compared to the first day of treatment. Although plasma growth hormone (GH) appeared to be elevated following the first TRH injection, this effect was not statistically significant (P less than .05), nor was it significantly influenced by treatment following subsequent TRH injections. None of the 3 hormones, PRL, TSH or GH, was elevated following the final TRH injection at 6 mo of age. In contrast, plasma concentrations of PRL and TSH were increased in a control heifer injected with TRH at 6 mo. These data indicate that hormonal responsiveness to TRH stimulation decreases with continued twice daily treatment at doses of TRH used in the present studies. Examination of weight gains indicated that chronic treatment with TRH was associated with increased growth rate through 6 mo of age (10.6% increased average daily gains P less than .10), which was exhibited in a steeper slope (P less than .05) of the growth curve in the TRH group. Feed intake was slightly greater in TRH heifers, although feed efficiency (kg feed/kg gain) was not different between the two groups. Plasma concentrations of PRL increased (P less than .01) with age (r = +0.938) in control heifers while plasma TSH and GH were not significantly related to age. This observation establishes a positive correlative relationship between PRL secretion and the approach of puberty in the dairly heirfer. It was also noted that elevation of PRL secretion by TRH treatment was associated with significant advancement of age at first observed estrus (9.4 vs. - 10.5 mo) suggesting that a functional relationship between PRL secretion and puberty may exist in dairy heifers. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/191244/Growth_rate_and_secretion_of_pituitary_hormones_in_relation_to_age_and_chronic_treatment_with_thyrotropin_releasing_hormone_in_prepubertal_dairy_heifers_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/endo-100-5-1394 DB - PRIME DP - Unbound Medicine ER -