Distribution of Fluorescence following Injection of Recombinant Adeno-Associated Virus Encoding Green Fluorescent Protein into the Paraventricular Nucleus

American Journal of Physiology-Endocrinology and Metabolism

Stanley²,

White³

et al. 2007

Bloom SR. Hypothalamic mapping of orexigenic action and Fos-like immunoreactivity following relaxin-3 administration in male Wistar rats. Am J Physiol Endocrinol Metab 292: E913-E919, 2007. First published November 28, 2006; doi:10.1152/ajpendo.00346.2006.-The insulin superfamily, characterized by common disulphide bonds, includes not only insulin but also insulin-like peptides such as relaxin-1 and relaxin-3. The actions of relaxin-3 are largely unknown, but recent work suggests a role in regulation of food intake. Relaxin-3 mRNA is highly expressed in the nucleus incertus, which has extensive projections to the hypothalamus, and relaxin immunoreactivity is present in several hypothalamic nuclei. In the rat, relaxin-3 binds and activates both relaxin family peptide receptor 1, which also binds relaxin-1, and a previously orphaned G protein-coupled receptor, RXFP3. These receptors are extensively expressed in the hypothalamus. The aims of these studies were twofold: 1) map the hypothalamic site(s) of the orexigenic action of relaxin-3 and 2) examine the site(s) of neuronal activation following central relaxin-3 administration. After microinjection into hypothalamic sites, human relaxin-3 (H3; 180 pmol) significantly stimulated 0-to 1-h food intake in the supraoptic nucleus (SON), arcuate nucleus (ARC), and the anterior preoptic area (APOA) [SON 0.4 Ϯ 0.2 (vehicle) vs. 2.9 Ϯ 0.5 g (H3), P Ͻ 0.001; ARC 0.7 Ϯ 0.3 (vehicle) vs. 2.7 Ϯ 0.2 g (H3), P Ͻ 0.05; and APOA 0.8 Ϯ 0.1 (vehicle) vs. 2.2 Ϯ 0.2 g (H3), P Ͻ 0.05]. Cumulative food intake was significantly increased Յ8 h following administration into the SON and 4 h into the APOA. A significant increase in Fos-like immunoreactivity was seen in the SON following central relaxin-3 administration. Relaxin-3 stimulates feeding in several hypothalamic nuclei, and these studies provide additional support for relaxin-3 as an important peptide in appetite regulation. relaxin family peptide receptor 3; appetite; supraoptic nucleus; arcuate nucleus THE INSULIN SUPERFAMILY of peptides is characterized by a common structure typified by one intrachain and two interchain disulphide bridges (20). In addition to insulin and insulin-like growth factors, the family also includes several insulin-like peptides: relaxin-1, relaxin-3, and insulin-like peptide-3, -4, -5, and -6 (5). Classical relaxin (H2 in humans, M1 in mice, and R1 in rats, referred to as relaxin-1 for clarity) is highly expressed in the female reproductive tract (36). Its primary roles appear to be in reproduction and parturition, but peripheral relaxin-1 also has marked effects on water intake (37, 45). The physiological role of the more recently described relaxin-3 remains largely unknown. In contrast to relaxin-1, relaxin-3 is expressed at the greatest levels in the central nervous system and primarily in the nucleus incertus (NI) of the brainstem (9, 44). This area has extensive projections to the forebrain, in particular to the hypothalamus, including the lateral hypothalamic and preoptic areas (18,44). In additio...

Section: Methodsmentioning

confidence: 99%

Hypothalamic mapping of orexigenic action and Fos-like immunoreactivity following relaxin-3 administration in male Wistar rats

American Journal of Physiology-Endocrinology and Metabolism

Stanley²,

White³

et al. 2007

“…) or 31-gauge (iPVN)), placed in and projecting 1 mm below the end of the cannula. Spread of a 1 ml injection into the PVN is reported to be limited to 1 mm 3 (Ward et al 2003).…”

Section: Icv and Ipvn Cannulation And Injectionmentioning

confidence: 99%

Relaxin-3 stimulates the neuro-endocrine stress axis via corticotrophin-releasing hormone

Journal of Endocrinology

Minnion

Murphy

et al. 2014

Relaxin-3 is a member of the insulin superfamily. It is expressed in the nucleus incertus of the brainstem, which has projections to the hypothalamus. Relaxin-3 binds with high affinity to RXFP1 and RXFP3. RXFP3 is expressed within the hypothalamic paraventricular nucleus (PVN), an area central to the stress response. The physiological function of relaxin-3 is unknown but previous work suggests a role in appetite control, stimulation of the hypothalamicpituitary-gonadal axis and stress. Central administration of relaxin-3 induces c-fos expression in the PVN and increases plasma ACTH levels in rats. The aim of this study was to investigate the effect of central administration of human relaxin-3 (H3) on the hypothalamic-pituitary-adrenal (HPA) axis in male rodents in vivo and in vitro. Intracerebroventricular (i.c.v) administration of H3 (5 nmol) significantly increased plasma corticosterone at 30 min following injection compared with vehicle. Intra-PVN administration of H3 (1.8-1620 pmol) significantly increased plasma ACTH at 1620 pmol H3 and corticosterone at 180-1620 pmol H3 at 30 min following injection compared with vehicle. The stress hormone prolactin was also significantly raised at 15 min post-injection compared with vehicle. Treatment of hypothalamic explants with H3 (10-1000 nM) stimulated the release of corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP), but H3 had no effect on the release of ACTH from in vitro pituitary fragments. These results suggest that relaxin-3 may regulate the HPA axis, via hypothalamic CRH and AVP neurons. Relaxin-3 may act as a central signal linking nutritional status, reproductive function and stress.

“…A 1μl iPVN injection was administered over 1 minute via a stainless steel 31-gauge injector, placed in and projecting 1mm below the end of the cannula. Spread of a 1µl injection into the PVN is reported to be limited to 1 mm 3 [14]. All compounds were dissolved in vehicle (10% acetonitrile in 0.9% saline) and studies were performed in satiated rats in the early light phase (0900 -1000h) unless otherwise stated.…”

Section: Intra-paraventricular Cannulation and Injectionmentioning

confidence: 99%

“…The filter was exposed to phosphoscreen overnight prior to quantification of UCP-1 mRNA expression using ImageQuant software (GE Healthcare, Chalfont St Giles, UK). Blots were reprobed with oligo(dT) [12][13][14][15][16][17][18] to enable differences in RNA loading to be corrected.…”

Section: Study 5: Effects Of 7 Day Repeated Ipvn Administration Of Rementioning

confidence: 99%

Effects of acute and chronic relaxin-3 on food intake and energy expenditure in rats

Stanley

Smith

et al. 2006

Regulatory Peptides

119

158

The effects of acute and repeated intraparaventricular (iPVN) administration of human relaxin-3 (H3) were examined on food intake, energy expenditure, and the hypothalamic-pituitary thyroid axis in male Wistar rats. An acute high dose iPVN injection of H3 significantly increased food intake 1 hour post-administration [0.4 ± 0.1g (vehicle) vs 1.6 ± 0.5g (180pmol H3), 2.4 ± 0.5g (540pmol H3) and 2.2 ± 0.5g (1620pmol H3), p< 0.05 for all doses vs vehicle]. Repeated iPVN H3 injection (180pmol/twice a day for 7 days) significantly increased cumulative food intake in ad libitum fed animals compared with vehicle [211.8 ± 7.1g (vehicle) vs 261.6 ± 6.7g (ad libitum fed H3), p< 0.05]. Plasma leptin was increased in the H3 ad libitum fed group. Plasma thyroid stimulating hormone was significantly decreased after acute and repeated administration of H3. These data suggest H3 may play a role in longterm control of food intake.