Pituitary gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) play central roles in regulating gametogenesis and the production of gonadal hormones, in fish as in other vertebrates. Pituitary gonadotropins are composed of two non-covalently associated polypeptide subunits, which must be glycosylated, folded, and assembled as a heterodimer to be biologically active. Si...

GnRH is potent stimulator of gonadotropin's alpha and beta chains synthesis in vivo. Stimulation of LH beta gene transcription requires pulsatile GnRH administration but the transcription of alpha subunit can be stimulated independently of GnRH mode of administration. Castration increases whereas in vivo estradiol and testosterone replacement decreases the rate of gene transcription of pituitar...

the hypothalamo-pituitary-adrenocortical (hpa) axis is a critical adaptive system that maximizes survival potential in the face of physical or psychological challenge. the principal end products of the hpa axis, glucocorticoid hormones, act on multiple organ systems, including the brain, to maintain homeostatic balance. the brain is a target of stress, and the hippocampus is the first brain reg...

Gonadotropin-inhibitory hormone (GnIH) is a novel hypothalamic neuropeptide that was discovered in quail as an inhibitory factor for gonadotropin release. GnIH inhibits gonadotropin synthesis and release in birds through actions on gonadotropin-releasing hormone (GnRH) neurons and gonadotropes, mediated via the GnIH receptor (GnIH-R), GPR147. Subsequently, GnIH was identified in mammals and oth...

To investigate the effects of alterations in GnRH pulse frequency on gonadotrophin secretion, we administered low dose GnRH pulses (25 ng/kg) at hourly or 2-hourly frequencies to eight normal men. All subjects received GnRH pulses i.v. every 2 h for 88 h. Following this, exogenous GnRH was discontinued in four normal men (Group A, GnRH withdrawal), and the frequency of GnRH injections was incre...

background: the pattern of islamic fasting differs from other forms of fasting, therefore its effect on health also differs. this research studies the effect of islamic fasting on gonadotropin hormones around the time of the ovulatory cycle and ovulation. materials and methods: this self-controlled study was performed on 24 adult females. blood sampling was performed during ramadan and two mont...

Hypogonadotropic hypogonadism is defined as a medical condition with low or undetectable gonadotropin secretion, associated with a complete arrest of follicular growth and very low estradiol. The main cause can be traced back to an irregular or absent hypothalamic GnRH secretion, whereas only a minority suffers from a pituitary disorder. The choice of treatment to reverse this situation is a pu...

Correspondence: Bernd Th Krause MvZ Uhlandstr. 19, 10623 Berlin, Germany Tel +49 3088716363 Fax +49 30887163659 email [email protected] Abstract: Hypogonadotropic hypogonadism is defined as a medical condition with low or undetectable gonadotropin secretion, associated with a complete arrest of follicular growth and very low estradiol. The main cause can be traced back to an irregular or absent ...

Regulation of ovarian activity is an integrated process encompassing both extraovarian signals and intrafollicular factors. Initiation of primordial follicle growth and the early stages of folliculogenesis can occur without gonadotropins, but FSH may affect the rate of preantral follicle growth. Antral follicle development from 1 to 4 mm in sheep and cattle is completely gonadotropin dependent....

In developed countries, contact with plastics is constant. Plastics contain a vast number of additives such as plasticisers, stabilisers, antioxidants, flame retardants, etc., that can impact human health. Most them have been studied separately; however, an integrative approach to identify genes, biological processes, molecular functions, and diseases linked exposure these compounds has not add...