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http://www.lifesci.susx.ac.uk/teaching/biochem/pfs/mei/. MOLECULAR ENDOCRINOLOGY AND IMMUNOLOGY Hypothalamic Hormones. Hormonal and neural integration. Neuroendocrinology Evidence for humoral control of anterior pituitary Isolation of hypothalamic hormones TRH GnRH (=LHRH)
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http://www.lifesci.susx.ac.uk/teaching/biochem/pfs/mei/ MOLECULAR ENDOCRINOLOGY AND IMMUNOLOGY Hypothalamic Hormones Hormonal and neural integration. Neuroendocrinology Evidence for humoral control of anterior pituitary Isolation of hypothalamic hormones TRH GnRH (=LHRH) GHRH and somatostatin CRH PIF Clinical aspects Biochemical mode of action
Evidence for control of anterior pituitary by humoral (blood-borne) factors [G.W.Harris] 1. Study of hypothalamo-hypophysial portal system - blood flows from capillary plexus in hypothalamus (median eminence) to capillary plexus in anterior pit. 2. Plate inserted into pit stalk causes decreased secretion of GH, FSH, LH, TSH and ACTH; increased secretion of PRL and ?MSH 3. Transfer of pit to kidney capsule has same effect as (2) 4. Electrical stimulation of parts of brain (esp hypothalamus) can lead to increased or decreased stimulation of pit hormones.
Hypothalamus (10-9g) Anterior pituitary (10-6g) Thyroid (10-3g) Peripheral tissues (1g) Schally; Guillemin; Vale
NH-CH-CO- | CH2 | OC-CH2 TSH releasing hormone (TRH) =
Rat proTRH LPEAAQEEGAVTPDLPGLENVQVRPERRFLWKDLQRVRGDLGAALDSWITKRQHPGKREE EEKDIEAEERGDLGEGGAWRLHKRQHPGRRANQDKYSWADEEDSDWMPRSWLPDFFLDSW FSDVPQVKRQHPGRRSFPWMESDVTKRQHPGRRFIDPELQRSWEEKEGEGVLMPEKRQHP GKRALGHPCGPQGTCGQTGLLQLLGDLSRGQETLVKQSPQVEPWDKEPLEE
LHRH (= GnRH) (pyro)Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 proLHRH QHWSYGRPGGKRDAELIDSFQEIVEVGQLAETQRFECTTHQPRS PLRDLKGALESLIEEETGQKKI
Somatostatin Precursor: Somatostatin-28 Somatostatin-14
GH SECRETION IN MALE RAT [GH] 3 6 9 12 h
ACTH releasing hormone (CRH) CRH CRH precursor
OH OH CH2 | CH2.NH3+ DOPAMINE
Signalling mechanisms of CRH From: Grammatopoulos & Chrousos (2003)