摘要:

The sites of stimulatory feedback of ovarian steroids on gonadotropìn release were examined. In estrogen-primed ovariectomized rats, estradiol or progesterone was implanted stereotaxically into various hypothalamic and extrahypothalamic areas. Both steroids elevated plasma LH and FSH levels at 6 h when implanted unilaterally into the preoptic-anterior hypothalamic area. Bilateral implants at this site were ineffective; presumably, this was due to the destructive lesion produced by the cannulae since in sham-implanted or anteriorly deafferented rats systemic estrogen was also ineffective. Unilateral estradiol implants in the medial basal hypothalamus elevated LH and FSH at 30 but not at 6 h. Maximum increases of plasma gonadotropins occurred 30 h after implantation of estradiol in the medial amygdaloid nuclei; progesterone implants at this site elevated only FSH at 6 h. Dissociation in the release of LH and FSH was also observed following implantation of estradiol into the hippocampus. Plasma FSH levels were dramatically reduced at 30 h while LH was slightly elevated. Progesterone implants in the hippocampus or medial basal hypothalamus did not alter plasma gonadotropìn level

ISSN:0028-3835    

DOI:10.1159/000122450

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The corticosterone content of the adrenal glands was determined in 21-day-old rat fetuses: before and after encephalectomy or decapitation (hypophysectomy); after ACTH treatment of the encephalectomized or decapitated (hypophysectomized) fetuses; and after administration of crude extracts (0.1 NHC1) of hypothalamic or cortical tissue from 20-day-old rat fetuses. A peak in the corticosterone content of the adrenals was observed 10 min after ACTH injection to encephalectomized or decapitated fetuses. A rise in corticosterone concentration was noted 5 and 10 min after the encephalectomized fetuses were given an injection of hypothalamic extract. This extract was devoid of appreciable ACTH activity when tested in decapitated fetuses. Cortical extract was inactive in encephalectomized or decapitated fetuses. These data suggest that fetal hypothalamic extract contains some CRF activity and that the fetal pituitary gland is responsive to the CRF.

ISSN:0028-3835    

DOI:10.1159/000122451

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Visual average evoked responses (AERs) to 4 intensities of light were studied in 5 patients with adrenal cortical insufficiency. Patients were tested off all medications, on ACTH while off all medications, and during replacement with carbohydrate-active steroids. Off treatment, when steroid levels were low, AERs were of small amplitude and short latency. Treatment with ACTH alone decreased the amplitude/intensity response, suggesting extra-adrenal effects. Both with amplitude and latency effects, stimulus intensity was an important parameter in determining steroid and ACTH effects.

ISSN:0028-3835    

DOI:10.1159/000122452

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Indolamine metabolism in the rat pineal is regulated by central influences mediated through the superior cervical sympathetics. The pineal stalk and medial habenular nucleus also have serotonin-containing cells and an innervation from the superior cervical ganglion (SCG). The present study was carried out to determine if the habenula and pineal stalk are similar to the pineal in certain aspects of indolamine metabolism. No diurnal rhythm in habenular serotonin content was observed, but ganglionectomy or decentralization of SCG results in a significant increase in habenular serotonin content. Unlike the pineal, the habenula and pineal stalk exhibit no rhythm in N-acetyltransferase (N-AT) activity; the activity of the enzyme in those tissues is comparable to low values of the diurnal rhythm in the pineal. N-AT activity in the pineal stalk and habenula is unaffected by sympathectomy. Similarly, there is little, if any, hydroxyindole-O-methyltransferase (HIOMT) activity in the pineal stalk and habenula; unlike the pineal, it is unaffected by continuous environmental lighting conditions or sympathectomy. These observations indicate that neither the pineal stalk nor the habenula represents a ‘deep’ pineal in the rat but that habenular indolamine metabolism is regulated by its peripheral sympathetic innervat

ISSN:0028-3835    

DOI:10.1159/000122453

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Serum LH and prolactin changes in response to an acute systemic L-dopa injection were measured in young (4–6 months) proestrous, estrous and 2nd day diestrous rats, and in aged (23–30 months) constant estrous and pseudopregnant (long diestrous) Long-Evans rats. Serum LH and prolactin were measured by radioimmunoassays in serial blood samples taken before and 15, 60 and 120 min after i.p. injections of 0, 3 or 30 mg of L-dopa. Pretreatment serum prolactin levels were elevated in afternoon samples from young proestrous and estrous rats and in both aged groups. Both the 3- and 30-mg injections caused a reduction in serum prolactin in all groups. The reduction in serum prolactin following 3 mg of L-dopa was less in both the aged groups than in the young rats. The pretreatment serum LH concentration was markedly elevated only on the afternoon of proestrus. The pretreatment serum LH level of the aged constant estrous group was greater than that of either the young estrous or diestrous group. Pretreatment serum LH levels were lower in aged pseudopregnant rats than in young diestrous rats. After the 30-mg L-dopa injection serum LH increased in all groups except the aged pseudopregnant group. Although the increase in LH following L-dopa injection was similar in young estrous and aged constant estrous rats, the increase in serum LH occurred later and lasted longer in the latter group. These data indicate that the hypothalamic-anterior pituitary endocrine control mechanisms are less responsive to acute L-dopa treatment in the aging female

ISSN:0028-3835    

DOI:10.1159/000122454

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

The effects of stress on plasma corticosterone and growth hormone (GH) were determined in adult female rats 24 h after forebrain removal in order to study the anatomical substrate essential for stress-induced alteration of pituitary function. Rats with median eminence-pituitary islands (MEPI) showed significant increments in plasma corticosterone levels 15 min after immobilization-blood withdrawal stress. Rats with basal hypothalamic-pituitary islands (BHPI) showed comparable increments, suggesting that the presence of hypothalamic tissue in addition to median eminence did not enhance the steroid response. A subsequent study demonstrated that MEPI rats are capable of a 2nd response, 6 h after thefirst. MEPI rats also showed a significant 50% increase in plasma GH levels 15 min after immobilization-blood withdrawal. In a final experiment, MEPI rats showed corticosterone but not GH responses to immobilization applied without blood withdrawal. These data offer further evidence that some stressful stimuli can alter pituitary functions under short-term conditions in the absence of hypothalamic or other forebrain neurons.

ISSN:0028-3835    

DOI:10.1159/000122455

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

We have tested the possibility that compensatory adrenal growth is neurally mediated. Small unilateral electrolytic lesions were made in the ventral hypothalamus of young male rats. Subsequently, unilateral adrenalectomy was performed on the side ipsilateral or contralateral to the hypothalamic lesion. Four days later the animals were killed and the remaining adrenal was weighed; the location and extent of the hypothalamic lesions were determined. Lesions placed on the same side as adrenalectomy prevented compensatory growth of the remaining gland (p < 0.005), while lesions on the side opposite to the removed adrenal did not interfere with compensatory adrenal growth. We conclude from these findings, and from a review of some anatomical studies, that compensatory adrenal growth is effected through a reflex that involves both afferent and efferent neural limbs.

ISSN:0028-3835    

DOI:10.1159/000122456

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

In an attempt to further characterize the nature of the innervation controlling melanophore-stimulating hormone (MSH) release from the pars intermedia (PI), pellets containing either apomorphine or ergocriptine were implanted in contact with the PI of the frog, and the effect on the animal’s coloration was observed. Frogs with apomorphine implants exhibited skin pallor for several hours and those with ergocriptine implants were pallid for a few days. Hypophysectomized (HX) frogs which had been darkened with MSH regained their pallor no sooner when given an injection of apomorphine than with the vehicle. However, intact dark frogs lightened when injected with apomorphine. Frogs darkened by autotransplantation of the PI to the dorsal lymph sac were lightened by an injection of apomorphine. Frogs lightened by an ergocriptine implant on the PI and then darkened by MSH did not lighten sooner than HX frogs given an injection of MSH. Ergocriptine-containing pellets implanted in the thigh took longer to produce the same effect than those implanted in contact with the PI. Since apomorphine is known to stimulate dopamine receptors in the central nervous system, and there is some evidence that ergocriptine does also, the above evidence supports the hypothesis that dopamine receptors are present in the P

ISSN:0028-3835    

DOI:10.1159/000122457

出版商:S. Karger AG    

年代:1975

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122458

出版商:S. Karger AG    

年代:1975

数据来源: Karger

ISSN:0028-3835    

DOI:10.1159/000122459

出版商:S. Karger AG    

年代:1975

数据来源: Karger