Vasoactive intestinal peptide modulates luteinizing hormone subunit gene expression in the anterior pituitary in female rat

Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Warsaw.
Brain Research Bulletin (Impact Factor: 2.72). 11/2005; 67(4):319-26. DOI: 10.1016/j.brainresbull.2005.07.007
Source: PubMed


The direct monosynaptic pathway which exists between vasoactive intestinal peptide (VIP) and GnRH neurons in the hypothalamic preoptic area provides a neuroanatomical background for the modulatory effects of VIP exerted on GnRH neurons activity. Though central microinjection of VIP revealed its involvement in the modulation of LH release pattern, there is a lack of data concerning a possible VIP influence on the alpha and LHbeta subunit gene expression in the pituitary gland. Using a model based on intracerebroventricular pulsatile peptide(s) microinjections (1 pulse/h [10 microl/5 min] over 5 h) the effect of exogenous VIP (5 nM dose) microinjection on subunits mRNA content in ovariectomized/oestrogen-pretreated rats was studied. Subsequently, to obtain data concerning the involvement of GnRH and VIP receptor(s) in the regulation of alpha and LHbeta subunit mRNA expression, OVX/estrogen-primed rats received a pulsatile microinjections of 5 nM VIP with 3 nM antide (GnRH receptor antagonist) or 5 nM VIP with 15 nM VIP 6-28 (VIP receptor antagonist). In this case, substances were given separately with a 30 min lag according to which each antagonist pulse preceded a VIP pulse. Northern-blot analysis revealed that VIP microinjection resulted in a decreased alpha and LHbeta mRNA content in pituitary gland and this effect was dependent on GnRH receptor activity. Moreover, obtained results indicated that centrally administered VIP might operate through its own receptor(s) because a receptor antagonist, VIP 6-28, blocked the inhibitory effect of VIP exerted on both LH subunit mRNA content and LH release.

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    • "As whisker stimulation induced c-Fos in GABA interneurons that selectively expressed VIP and ACh, we then evaluated the implication of these established vasoactive mediators in the evoked CBF response. Surprisingly, blockade of vasodilatory mAChR or VIP receptors using antagonists [scopolamine or VIP(6 –28)] with reported efficacy on stimulusevoked CBF responses (Nakao et al., 1999; Kocharyan et al., 2008) or other CNS functions (Gajewska et al., 2005) did not affect this hyperemic response, even after 40 or 60 min (Fig. 4C). Similarly, blockade of GABA-B receptors with CGP35348 (tested up to 10 Ϫ2 M) failed to alter the CBF response (Fig. 4C, for 10 Ϫ4 M). "
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