Increased ovulation and twin-calving rates in heifers immunized against bovine inhibin peptides

Inhibin is a dimeric protein hormone composed of two dissimilar, disulphide-linked subunits (termed α and β) involved in the negative feedback regulation of gonadotrophin secretion, preferentially FSH. Interfering with this negative feedback by active immunization against inhibin has resulted in a consistent increase in ovulation rate and litter size in sheep. However, similar results have not been achieved in cattle. This paper describes the effect of active immunization of heifers against either of 3 synthetic peptide sequences from the bovine inhibin α-subunit on inhibin antibody titres, ovulation rate, calving rate and twin-calving rate.Three peptide sequences from the bovine inhibin a-subunit were identified as likely immunological epitopes by computer analysis. These peptides (P1: bl-α-[YG] (18-30); P2: bl-α-(63-72)[GY]; P3: bl-α-[CG](107-122) were synthesized by solid phase methods and tyrosyl or cystenyl residues, linked through a glycine spacer where appropriate, were added during synthesis in order to facilitate iodination and conjugation respectively.

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Initiation of active immunization against testosterone during early puberty alters negative feedback regulation of the hypothalamic-pituitary-testicular axis in rabbits

Domestic Animal Endocrinology ◽

10.1016/j.domaniend.2014.04.001 ◽

2014 ◽

Vol 48 ◽

pp. 126-135 ◽

Cited By ~ 3

Author(s):

X.F. Han ◽

W. Cheng ◽

Z.Y. Chen ◽

X.G. Du ◽

X.H. Cao ◽

...

Keyword(s):

Negative Feedback ◽

Feedback Regulation ◽

Active Immunization ◽

Early Puberty ◽

Negative Feedback Regulation

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Structural and Functional Coupling of Calcium-Activated BK Channels and Calcium-Permeable Channels Within Nanodomain Signaling Complexes

Frontiers in Physiology ◽

10.3389/fphys.2021.796540 ◽

2022 ◽

Vol 12 ◽

Author(s):

Kunal R. Shah ◽

Xin Guan ◽

Jiusheng Yan

Keyword(s):

Signal Transduction ◽

Ion Channels ◽

Negative Feedback ◽

Feedback Regulation ◽

Bk Channels ◽

Bk Channel ◽

Functional Coupling ◽

Negative Feedback Regulation ◽

Α Subunit ◽

Functional Studies

Biochemical and functional studies of ion channels have shown that many of these integral membrane proteins form macromolecular signaling complexes by physically associating with many other proteins. These macromolecular signaling complexes ensure specificity and proper rates of signal transduction. The large-conductance, Ca2+-activated K+ (BK) channel is dually activated by membrane depolarization and increases in intracellular free Ca2+ ([Ca2+]i). The activation of BK channels results in a large K+ efflux and, consequently, rapid membrane repolarization and closing of the voltage-dependent Ca2+-permeable channels to limit further increases in [Ca2+]i. Therefore, BK channel-mediated K+ signaling is a negative feedback regulator of both membrane potential and [Ca2+]i and plays important roles in many physiological processes and diseases. However, the BK channel formed by the pore-forming and voltage- and Ca2+-sensing α subunit alone requires high [Ca2+]i levels for channel activation under physiological voltage conditions. Thus, most native BK channels are believed to co-localize with Ca2+-permeable channels within nanodomains (a few tens of nanometers in distance) to detect high levels of [Ca2+]i around the open pores of Ca2+-permeable channels. Over the last two decades, advancement in research on the BK channel’s coupling with Ca2+-permeable channels including recent reports involving NMDA receptors demonstrate exemplary models of nanodomain structural and functional coupling among ion channels for efficient signal transduction and negative feedback regulation. We hereby review our current understanding regarding the structural and functional coupling of BK channels with different Ca2+-permeable channels.

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