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PubMedDate not supplied

[In vitro study of the interaction between neuromediators and neuropeptides involved in hypothalamic neurosecretion control (author's transl)].

Luteinizing hormone-releasing hormone (LHRH) and somatostatin (SRIF) release was assessed in superfused slices of mediobasal hypothalamus. Release of both neurohormones by depolarizing agents (K+, 56mM ; veratridine, 50 muM) was shown to be Ca2+-dependent, according with the stimulus-secretion coupling hypothesis. Opiates (beta endorphin, 10(-7)M and D-ALA2-Met-enkephalinamide 10(-7)M) did not alter the spontaneous release of LHRH and SRIF, but inhibited significantly the K+-induced neuropeptide release. The effect was reversed by the opiate antagonist naloxone (10(-7)M), while naloxone was ineffective by itself. Vasoactive intestinal peptide (VIP 10(-9)M) significantly inhibited K+ evoked release of SRIF ; LHRH release was unaffected. The effect of VIP on SRIF release was dose-dependent ; secretin, a partial VIP agonist, was also active at higher doses. The data suggest that : 1) opiates, acting through specific opiate receptors located on LHRH and SRIF neurons, modulate the release of the neurohormones ; 2) the inhibitory effect of opiates could be due to an inhibition of calcium influx through voltage-dependent calcium channels ; 3) this interaction may account for the stimulation of growth hormone and the inhibition of luteinizing hormone observed after systemic administration of opiates ; 4) VIP inhibits SRIF release, by acting on VIP receptors present on MBH SRIF terminals ; the effect is consistent with the stimulation of GH reported after in vivo administration of the peptide.

Endorphins↗
PubMed1982

Physiological dependency between the hypothalamus and the thymus in Wistar rats. II. The neurosecretion level and microstructural changes following para-chlorophenylalanine administration. The differences in DL-5-hydroxy G-3H tryptophane incorporation in the hypothalamus of normal and thymectomized rats.

The experiments were carried out on male Wistar rats, both normal and thymectomized in which the thymus was excised in 12th h of life. 8 weeks later, the animals were administered parachlorophenylalanine [PCPA], i.e. a compound inhibiting tryptophane hydroxylase, in the amount of 200 mg/kg of body weight. The studied hypothalamus preparations, i.e. supraoptical [NSO] and paraventricular nuclei [NPV] revealed an increased level of Gomori-positive neurosecretory material in thymectomized rats when compared to control animals. It was observed that the former rodents manifested an elevated incorporation of the isotope, i.e. DL-5-Hydroxy [G-3H] Tryptophane. The calculations performed by the use of the Gosset's t-test ("Student's") showed that the difference was statistically significant (p less than 0.001).

5-Hydroxytryptophan↗
PubMed1983

[Role of the neurosecretion of the supraoptic and paraventricular hypothalamic nuclei in the pathogenesis of experimental urolithiasis].

Experiments made on male rats fed oxamide during 10 days provided new data on the changes in the morphofunctional status of the hypothalamo-hypophyseal neurosecretory system (HHNS) in the course of the development of urolithiasis. The changes develop in three stages. The first stage is marked by an increase of the HHNS functional activity, the second one by its decrease, and the third one by its recovery. It is concluded that the changes in the secretion of antidiuretic hormone produced by supraoptic and paraventricular nuclei of the hypothalamus are involved in the pathogenesis of urolithiasis, which should be taken into account in multiple modality treatment of the disease.

Animals↗