Sándor Vigh

Ontogenetic development of corticotropin-releasing factor (CRF)-containing neural elements in the brain of the chicken during incubation and after hatching.

SummaryIn chicken embryos of different ages and in young chickens after hatching, neural elements reacting with antibodies generated against synthetic ovine corticotropin-releasing factor (CRF) were studied by means of the peroxidase-anti-peroxidase (PAP) technique at the lightmicroscopic level. CRF-immunoreactivity was first observed in perikarya located in the periventricular part of the hypothalamus on the 14th day of the incubation period. CRF-containing neural elements were detected on the same day of incubation in the external zone of the median eminence, but not in all investigated animals. In extrahypothalamic sites, immunoreactive perikarya were demonstrable in the central gray of the mesencephalon on the 15th day of incubation. Furthermore, immunoreactive cells appeared in other brain regions such as nucleus accumbens and dorsomedial nucleus of the thalamus after hatching. The present observations provide information regarding the functional development of the hypothalamo-hypophyseal-adrenal axis in the chick embryo.

Comparison of in vitro and in vivo effects of different species specific GnRH and their analogs

Mammalian, salmon and chicken gonadotropin-releasing hormones (mGnRH, sGnRH, cGnRH) and their analogs were synthesized and tested for their ability to stimulate in vitro LH and FSH release from cultured and superfused rat pituitary cells and also their in vivo effect were investigated on the artificial propagation of fishes. The LH and FSH releasing activity of sGnRH, cGnRH and their analogs were lower than the appropriate mammalian ones from cultured rat pituitary cells, but two of the cGnRH analogs showed increased LH and FSH secretory activity from superfused rat pituitary cells compared to the mGnRH. At the same time these two analogs are very potent to stimulate reproductive function of fishes and using these peptides we were able to fulfill the artificial propagation of fishes which could not be artificially propagated before.

Potent GnRH agonists containing L-amino acid derivatives in the six position

New agonists related to gonadotropin-releasing hormone (GnRH) have been synthesized that are comparable in potency to the GnRH and its superagonists for release of LH and estrus suppression without substitutions with D- or unnatural amino acids in position 6. We now report a series of L-beta-aspartyl-6 GnRH analogs containing only naturally occurring L-amino acids in the whole sequence, exhibiting considerable in vivo biological activity. Dose and time dependent LH release capability of the different analogs in adult male mice, estrus suppression comparisons and blockade of ovulation in female rats are given. The incorporation of L-Asp-OMe and L-Asp-OBzl in position 6 of GnRH resulted in the most potent GnRH agonists (to 12-20xGnRH potency) in this series inducing a biphasic biological response similar to the D-amino acid-6 substituted superactive GnRH analogs. A correlation between the LH releasing potencies of the analogs and their HPLC retention times was also investigated. Peptide synthesis were achieved using either solid phase or solution phase methodology.

Localization of LH-RH-containing Neurons in the Rabbit Brain

In the last three years immunohistologic methods have successfully been used to localize the hypophysiotrophic (releasing and inhibiting) hormones. The first releasing hormone localized by immunohistologic methods in the guinea pig by LEONARDELLI et al. in 1973 was luteinizing hormone-releasing hormone (LH-RH). The species studied so far for the histologic localization of LH-RH include guinea pig, rat, mouse, duck, toad, cat, dog, and greenfinch (BARRY and CARETTE, 1975; SETALO, 1976).