Nine-month-old female rats bearing an ectopic pituitary gland (from a litter-mate) under the right kidney capsule since day 30 of life and their sham-operated controls, were treated with a dopamine agonist (lysuride) or antagonist (metoclopramide). Plasma prolactin and LH levels were measured by double-antibody radioimmunoassays. Vaginal smears were taken before and during the treatment periods. Eight months after the operation, a significant (P < 0·01) increase in basal prolactin levels together with a significant (P < 0·05) reduction in LH values and permanent dioestrus occurred in the grafted animals when compared with controls. Lysuride treatment resulted in a marked reduction in plasma prolactin levels both in control and grafted rats over the whole 12 days of treatment, together with a partial restoration of plasma LH levels on day 1. From day 7 onwards a depression in LH values was again observed. Oestrous cycles were partially restored at the beginning of the treatment, but after 7 days dioestrus returned. Metoclopramide administration induced a significant (P< 0·001) increase in basal prolactin levels in both grafted and control rats. Basal plasma LH values were unaffected in controls when compared with vehicle-treated animals. An increase could be seen in hyperprolactinaemic rats after 7 or 12 days of treatment however. The LH response to the administration of LH releasing hormone (LHRH) was greater in the experimental and control metoclopramide-treated rats when compared with vehicle-treated rats. Vaginal smears were not altered in the control animals but there was a significant increase in the number of oestrous smears in grafted animals given the dopamine antagonist partially restoring the cycle pattern. After LHRH administration plasma prolactin levels decreased in vehicle-treated grafted and control animals, whereas only a tendency to lower values or no modification in basal levels was observed with lysuride or metoclopramide treatments. All these data suggest that increased plasma prolactin levels cannot modify LH secretion directly. This influence may be exerted, however, through increased hypothalamic and in-situ pituitary dopamine detected in hyperprolactinaemic animals.
J. Endocr. (1984) 100, 141–148
Journal of Endocrinology is committed to supporting researchers in demonstrating the impact of their articles published in the journal.
The two types of article metrics we measure are (i) more traditional full-text views and pdf downloads, and (ii) Altmetric data, which shows the wider impact of articles in a range of non-traditional sources, such as social media.
More information is on the Reasons to publish page.
| Sept 2018 onwards | Past Year | Past 30 Days | |
|---|---|---|---|
| Full Text Views | 1 | 0 | 0 |
| PDF Downloads | 1 | 0 | 0 |
Online ISSN: 1479-6805
Print ISSN: 0022-0795
Strengthening biomedical communities
to advance science and health
CONTACT US
Bioscientifica Ltd | Starling House | 1600 Bristol Parkway North | Bristol BS34 8YU | UK
Bioscientifica Ltd | Registered in England no 3190519
