摘要:

Pimozide and haloperidol, the dopaminergic antagonists, have been shown to effectively block diethylstilbestrol (DES)-elicited [3H] adenosine 3’, 5’-monophosphate (cAMP) accumulation in incubated hypothalami from immature male rats. Several noradrenergic antagonists (i.e. propranolol, MJ-1999 and phenoxybenzamine) failed to reduce [3H]cAMP levels significantly. Pimozide was found to be more specific than haloperidol as it did not effect norepinephrine (NE)-elicited formation of [3H]cAMP, while the latter blocker caused a 48% reduction of the stimulation by NE. Pimozide was also more potent than haloperidol in inhibiting DES-stimulated [3H]cAMP formation. It can be inferred from these data that as a result of DES-receptor interaction dopamine (DA) is released and in turn activates DA-sensitive adenylate cyclase in the hypothala

ISSN:0028-3835    

DOI:10.1159/000122506

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Ergonovine maleate inhibits melanophore stimulating hormone (MSH) secretion from the incubated frog, rat, and mouse pituitary gland. This ergot alkaloid is partially effective at a concentration as low as M. The inhibitory effect on hormone release is irreversible under the experimental conditions studied. Ergonovine inhibition of MSH secretion is blocked by Dibenamine and chlorpromazine as is dopamine inhibition of MSH secretion. At higher concentrations chlorpromazine displays an intrinsic ability to inhibit MSH secretion. Similarities between the cellular mechanisms controlling MSH and prolactin secretion will be discussed.

ISSN:0028-3835    

DOI:10.1159/000122605

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The effects of suckling and LH upon serum progesterone levels in lactating hamsters were investigated. Diurnal rhythms in serum levels of progesterone and LH occur throughout lactation in the hamster and these levels are normally higher between 15.00 and 17.00 than between 8.00 and 12.00 (lights on 6.00–20.00). Hamsters injected with 10 µg of LH at 8.00 on day 9 of lactation had higher levels of serum progesterone 2 h after injections than did vehicle-injected controls. Suckling was also found to induce an increase in serum progesterone concentrations. 30 min of suckling from 10.30 to 11.00 on days 10 or 11 of lactation resulted in increased serum levels of progesterone and prolactin, but had no measurable effect upon serum LH levels in animals bled at 11.00. However, suckling for 30 min from 15.00 to 15.30 had no effect upon serum progesterone levels, although it did result in increased titers of both serum LH and prolactin at 15.30. Ovariectomy on day 7 of lactation resulted in lowered levels of serum progesterone at 11.00 on day 11 of lactation and abolished the suckling-induced increase in serum progesterone concentrations. These findings suggest that in the lactating hamster (1) suckling bouts stimulate progesterone secretion from the ovaries, and (2) the diurnal rise in serum progesterone levels is stimulated in part by the increase in serum levels of

ISSN:0028-3835    

DOI:10.1159/000122507

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Acetylcholine (1 and 50 µg), carbamylcholine (1 and 10 µg), and oxotremorine (10 µg) were infused into the 3rd ventricle of rats with deafferented medial basal hypothalamus (MBH); infusions failed to stimulate ACTH release as shown by the plasma corticosterone level. Implants of an atropine-fluorescein mixture (200–250 µg) inhibited the stress-induced rise of plasma corticosterone only when dye from the implant stained large portions of the median eminence and the basal hypothalamus. Atropine implants near the electrodes inhibited the rise in plasma corticosterone usually produced by electrical stimulation in the anterior hypothalamus. Atropine crystals or a 2% atropine sulphate solution placed on the median eminence blocked conduction of action potential in the hypothalamo-neurohypophyseal and tubero-infundibular pathways. The evidence will be discussed for and against the participation of a cholinergic synapse (in the MBH) that activates ACTH release after stressful neural st

ISSN:0028-3835    

DOI:10.1159/000122508

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

When electroshock therapy was administered to male psychiatric patients without anticonvulsive premedication, serum growth hormone (GH) increased; the increase was not prevented by an infusion of 20% glucose (5 ml per min) 20 min prior to electroshock. Therefore, the GH rise is not caused by muscle exercise during convulsions. Infusing 30 mg of phentolamine 40 min prior to electroshock inhibited the GH response. Phentolamine’s effect shows that the stress-induced GH release that follows electroconvulsive therapy is mediated by alpha-adrenergic neuron

ISSN:0028-3835    

DOI:10.1159/000122509

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Neonatal rats were given s.c. injections of 1 mg of hydrocortisone acetate, and the effect on the subsequent development of the pituitary-adrenal response to ether stress and the development of the circadian rhythm in adrenal and serum corticosterone (B) was investigated. Following exposure to ether, adrenal steroids were elevated in 11-day-old controls. The response did not appear in treated animals until 25 days. At this age, the time-course of response to ether in the adrenal was more sluggish in hormone-treated rats. After stress, serum corticoids were high in controls at 20 days; however, this rise did not appear in treated rats until 25 days. Serum corticoids, 5–60 min after ether, tended to be lower in 25-day-old runts than in controls. The diurnal rhythm in serum B first appeared in controls at 27 days and in treated animals at 30 days. The rhythm in adrenal corticoids appeared in both groups at 30 day

ISSN:0028-3835    

DOI:10.1159/000122510

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Twice a week male rats were given injections of 1 mg estradiol benzoate as an aqueous microcrystalline suspension; they were also given 0.1, 0.2 or 0.4 mg Pimozide (a dopamine receptor blocker) daily in their food. Only the maximum Pimozide dose potentiated the effect of estradiol on adenohypophysial weight and on the binding capacity of adenohypophysial proteins for thyroxine in vitro. The estrogen-induced increase in the serum ceruloplasmin level, however, was potentiated significantly by all 3 Pimozide doses.

ISSN:0028-3835    

DOI:10.1159/000122511

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Female rats raised from birth under a light/dark (LD) or constant light (LL) regimen were given injections at either 24, 29, 33 or 35 days of age of either 5 IU PMSG or 0.1 ml saline. Two days following PMSG or saline injection, the rats were given injections of either 1,000 ng synthetic gonadotropìn releasing hormone (GnRH) or 0.1 ml saline. Blood samples were taken before and 20 min after injection for LH determinations. PMSG caused a rise in basal LH levels, which was greater in LL than in LD animals. GnRH administration resulted in an LH surge in both LD and LL rats at all ages tested. The LL animals released greater amounts of LH in response to GnRH than did LD animals. In PMSG-primed animals there were no differences in the GnRH-induced LH surge due to either age or photoperiod. It is concluded that PMSG and LL enhance the pituitary’s response to Gn

ISSN:0028-3835    

DOI:10.1159/000122512

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The effect of steroid contraceptive drugs (SCDs) on the concentration of dopamine (DA) in the striatum was studied in mice and rats. Mestranol was combined with each one of the three progestins, lynestrenol, norethindrone and norethynodrel. Treatments were given daily for 1, 4 or 30 days; animals were sacrificed 1 or 18 h after the last administration. In all groups, with the exception of the animals sacrificed 1 h after an acute treatment, striatal DA was significantly lower than in controls.

ISSN:0028-3835    

DOI:10.1159/000122513

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Several neurally excitant amino acids were injected into the third ventricle of anesthetized male rats, and plasma levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured. LH levels increased following injections of 2.0 µm glutamate, lysine, or β-alanine. Glycine (2.0 µm), α-alanine (2.0 µm), and 0.9% saline were ineffective in altering LH levels. None of the amino acids tested significantly altered FSH levels. Of the 3 amino acids which raised blood LH levels following an intraventricular injection, i.e., glutamate, β-alanine, and lysine, only lysine caused a significant increase in LH levels following injection into the pituitary. The present study provides evidence for a possible role for certain neurally excitant amino acids in the neuronal control of LH secr

ISSN:0028-3835    

DOI:10.1159/000122514

出版商:S. Karger AG    

年代:1976

数据来源: Karger