Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Hypophysectomy”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources
PubMed1981

Hypophysectomy induced hypersensitivity to dopamine: antagonism by estrogen.

Hypophysectomized (HYPOX) or sham HYPOX (SHAM) and ovariectomized rats were injected with either estradiol benzoate (EB, 10 microgram/kg/day x 3) or sesame oil (0.25 ml/kg/day x 3). Twenty hours after the last dose of EB or oil all animals were injected with apomorphine and the resulting stereotypy scored. The HYPOX + oil group was more sensitive to the apomorphine than the SHAM + oil group (ED50 = 0.24 and 0.45 mg/kg, respectively). Treatment with EB resulted in a shift to the right of the dose response curves for both the HYPOX and SHAM groups. The ED50 for the HYPOX group was increased to 0.62 mg/kg, while the SHAM group increased to 0.93 mg/kg. The Bmax values for [3H]spiroperidol binding to striatal membranes were not significantly different for the HYPOX + EB, SHAM + EB, or SHAM + oil groups. However, the HYPOX + oil group was significantly increased (54%) at 7 days post-HYPOX. By 28 days post-HYPOX, the Bmax for the HYPOX animals had increased by 94% relative to SHAM animals. The HYPOX induced increase in dopamine sensitivity could be increased by chronic treatment and withdrawal of haloperidol. The haloperidol induced increase in apomorphine induced stereotypy and [3H]spiroperidol binding could be antagonized by EB treatment during the withdrawal phase of the haloperidol treatment. These data indicate that the pituitary has a modulating effect on striatal spiroperidol binding and apomorphine induced stereotypy, but that its presence is not required for estrogen to suppress the efficacy of dopamine or dopamine agonists.

Animals↗
PubMed1982

The influence of selective adeno- and neurointermedio-hypophysectomy upon plasma and brain levels of beta-endorphin and their response to stress in rats.

Selective ablation of the anterior lobe (AL) of the pituitary led to a fall in basal plasma levels of beta-endorphin immunoreactivity (beta-EI) at 3 and 20 weeks post-surgery (p.s.). Further, the stress-evoked rise in circulating levels of beta-EI was abolished. This operation did, however, severely deplete the beta-EI content of the neurointermediate lobe (NIL). Removal of the NIL did not, in contrast, decrease the beta-EI content of the AL but depressed basal plasma levels of beta-EI at 3 weeks p.s. and attenuated, but did not abolish, the increase in these elicited by stress at both 3 and 20 weeks p.s. In rats not possessing a NIL, a secretion of beta-EI into plasma can thus occur. The possibility that NIL pools of beta-EI contribute to circulating levels of beta-EI is discussed. Removal of the AL depressed the beta-EI content of the hypothalamus and periventricular tissue at 3 and 20 weeks p.s. The Met-enkephalin-immunoreactivity (ME-I) content of the hypothalamus was, in contrast, unaffected. These animals still responded to stress at 20 weeks p.s. with a significant fall in hypothalamic levels of beta-EI. Extirpation of the NIL did not, in contrast, change brain levels of either beta-EI or ME-I. The presence of the AL, but not the NIL, is thus essential for the maintenance of usual levels of beta-EI and ME-I in the brain.

Animals↗
PubMed1986

Effect of hypophysectomy on somatostatin-14 and somatostatin-28 biosynthesis in the rat hypothalamus.

The in vivo incorporation of [35S]cysteine into hypothalamic somatostatin-28 was found to be substantially below normal in hypophysectomized rats. A smaller reduction in label incorporation into arginine vasopressin was also observed, while incorporation into acid-precipitable protein was normal. The diminution in somatostatin biosynthesis presumably reflects the absence of pituitary growth hormone secretion, while that in vasopressin synthesis may reflect the loss or disruption of vasopressin-producing cells.

Animals↗
PubMed1987

The effect of hypophysectomy, ACTH fragments and thalamic lesions upon kindled epilepsy.

Hypophysectomized rats showed aberrant and retarded rates of kindled epilepsy. In hypophysectomized rats administered adrenocorticotropic hormone (ACTH) subunits ACTH4-10 and ACTH1-24, the normal kindling pattern was restored. However, in hypophysectomized animals which also had lesions of the thalamus (nucleus parafascicularis), ACTH4-10 did not restore the normal pattern of kindling. There have been many conjectures that kindling may be a subcase of learning. These results are compatible with this hypothesis, since the same procedures act in an analogous fashion within avoidance conditioning paradigms.

Adrenal Glands↗
PubMed1982

Hypophysectomy reduces the haloperidol-induced changes in striatal dopamine receptor density.

The ability of haloperidol (HAL) at doses of 1, 2 and 4 mg/kg to increase the density of the striatal dopamine (DA) receptors was measured in normal and hypophysectomized (Hypox) male rats. In intact rats HAL significantly increased the receptor density at all three doses. In Hypox rats HAL produced significantly less of an increase, with only the 4 mg/kg dose producing a statistically significant increase. Therefore, Hypox appears to reduce the ability of HAL to increase striatal DA receptor density.

Analysis of Variance↗