Modulation by Galanin of Growth Hormone and Gonadotropin Secretion from Perifused Pituitary and Median Eminence of Prepubertal Male Calves

Baratta, Mario; Saleri, Roberta; Mascadri, C; Coy, David H.; Negro‐Vilar, A.; Tamanini, Carlo; Giustina, Andrea

doi:10.1159/000127248

Cited by 27 publications

(21 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…GnRH-induced LH release was even attenuated by galanin in a dose-dependent manner when either dispersed AP cells or AP fragments harvested at proestrus were used, while galanin did not affect GnRH-stimulated LH release from dispersed AP cells harvested at estrus or diestrus [19]. On the other hand galanin increased LH release from perifused AP fragments collected from prepubertal male calves but did not modulate LH responsiveness to GnRH [24]. These findings point out to the importance of the estrous cycle stage and important species differences in the hypophysiotropic function of galanin.…”

Section: Discussionmentioning

confidence: 99%

“…Galanin has thus been reported to act at the level of the pituitary to enhance the LH surge evoked by GnRH hypersecretion [18]; for review see 3], but also to inhibit LH release [19]. Similarly evidence suggests modulation of GH release, as demonstrated in rats [20, 21, 22], in humans [23]and bovine species [24]. …”

Section: Introductionmentioning

confidence: 99%

“…Except for a recent paper [24]demonstrating a significant stimulatory role of galanin in the secretion of LH and GH in the bovine, evidence for pituitary modulation of LH and GH secretion by galanin in species other than the rat and human is lacking. Evidence that galanin plays a role in the auto/paracrine control of pituitary LH secretion was missing until very recently [19]although such role has been repeatedly suggested in view of the presence of galanin mRNA, peptide and receptor in the pituitary [for review see 11, 12].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Stimulation of Porcine Pituitary Luteinizing Hormone Release by Galanin: Putative Auto/Paracrine Regulation

Elsaesser¹

2001

Neuroendocrinology

View full text Add to dashboard Cite

It has repeatedly been suggested that galanin acts within the anterior pituitary (AP) in an auto/paracrine manner to modulate luteinizing hormone (LH) release. Except for one recent report in the rat, evidence for this notion is absent. The purpose of this study was to investigate in the pig the effects of galanin on LH and growth hormone (GH) release and to evaluate putative local effects using various AP culture systems (monolayer, perifusion, reaggregates). Independent of age galanin dose dependently (0.05, 0.2, 1 µM) stimulated basal but not gonadotropin-releasing hormone (GnRH; ≧0.01 nM)-induced LH release. Neither basal nor GH-releasing hormone (GHRH)-stimulated GH release was affected at any age. Of 4 galanin receptor antagonists (0.2, 1 µM) tested C7 proved to have agonistic effects, whereas M40 and M15 (galantide) were ineffective in blocking galanin (0.2 µM)-induced LH secretion or affecting basal or GnRH-induced LH release. M32 [galanin (1–13) NPY (25–36) amide] inhibited (p ≤ 0.05) GnRH-induced LH release at doses of ≧2 µM, an effect which could be totally compensated by 1 µM galanin. However, the neuropeptide (NPY) antagonist BIBP 3226 (1 µM) partially overcame the effect of M32 (M32 is known to also bind to NPY receptors and NPY is inhibitory in the pig). In further studies using APs from preovulatory gilts a specific well-characterized galanin antiserum diluted 1:20 or 1:50 attenuated GnRH-induced LH release (p ≤ 0.05). However, an NPY antiserum (also affinity purified and at the same dilution) used as control unexpectedly inhibited GnRH (and galanin)-induced LH release as well, thus suggesting that attenuation of GnRH-induced LH release by galanin antiserum might be at least partly nonspecific. Furthermore 96-hour exposure of AP reaggregates to two types of porcine preprogalanin antisense oligodeoxynucleotides neither affected basal nor GnRH-induced LH release. In line with the failure to unequivocally prove paracrine effects of galanin, concentrations of galanin in AP cultures and AP culture medium were very low (≤2 pg galanin/10⁵ AP cells). In conclusion the present study provides some evidence to ascribe a hypophysiotropic role to galanin in regulating LH but not GH secretion in the pig. The study also points to the critical role of appropriate controls when trying to prove auto/paracrine control mechanisms within the anterior pituitary. Our findings do not provide convincing evidence to support the notion that intrapituitary galanin is involved in the fine tuning of LH secretion, at least in the preovulatory pig.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stimulation of Porcine Pituitary Luteinizing Hormone Release by Galanin: Putative Auto/Paracrine Regulation

Elsaesser¹

2001

Neuroendocrinology

View full text Add to dashboard Cite

show abstract

“…First, direct infusion of galanin into the cerebral ventricles of E 2 -treated ovariectomized rats increases LH secretion [5, 6]; second, this increase is blocked by preinfusion of galantide (a galanin antagonist) [5], and third, galanin elicits release of GnRH from AME fragments [3, 4, 5]. Galanin may also act on gonadotropes, since galanin enhances LH secretion from pituitary fragments of female rats [3], and similar effects are seen in pituitary fragments of prepubertal male calves [32]. Here, we provide evidence that galanin, given by peripheral administration, can stimulate LH secretion in the monkey.…”

Section: Discussionmentioning

confidence: 99%

Galanin’s Functional Significance in the Regulation of the Neuroendocrine Reproductive Axis of the Monkey

Ky²,

Hg³

et al. 2000

Neuroendocrinology

View full text Add to dashboard Cite

Galanin stimulates the neuroendocrine reproductive axis in the rat, but whether galanin acts similarly in primate species is unknown. To test the hypothesis that galanin acts within the hypothalamo-hypophyseal axis to stimulate luteinizing hormone (LH) and gonadotropin-releasing hormone (GnRH) secretion in the primate, galanin was administered either systemically or directly into the arcuate nucleus-median eminence of ovariectomized macaques (pigtailed or rhesus, respectively) that were maintained on estradiol. The mean plasma levels of LH were significantly elevated in pigtailed macaques after peripheral injection of galanin (2 mg) as compared with vehicle treatment. In rhesus monkeys, galanin (80 µM) administered by push-pull perfusion into the arcuate nucleus-median eminence did not significantly alter either GnRH or LH release. To determine whether in the monkey, as in the rat, subpopulations of medial forebrain GnRH neurons coexpress galanin mRNA, we used single- and double-label in situ hybridization and computerized imaging techniques. GnRH mRNA-containing cells were identified in both the medial and lateral forebrain of the female pigtailed macaque. No galanin mRNA expression was detectable in GnRH neurons located in either the medial preoptic area or mediobasal hypothalamus; however, within the substantia innominata a subset of GnRH mRNA-expressing neurons did coexpress galanin mRNA. Taken together, these results suggest that galanin induces LH release in primates, but galanin may not act directly on hypothalamic GnRH neurons. Presently, we have confirmed in another primate species the existence of GnRH gene expression in the lateral forebrain and discovered that a small subset of these neurons coexpress galanin. These particular cells may have a unique and as of yet undefined physiological function that is distinct from those GnRH neurons serving a hypophysiotropic function.

show abstract

“…Growth hormone was assayed by validated double-antibody radioimmunoassays (RIA) (Baratta et al, 1997). Briefly, GH was radio-iodinated with 125I according to Salacinski et al (1981).…”

Section: Blood Analysesmentioning

confidence: 99%

Effects of short-term feed restriction on milk yield and composition, and hormone and metabolite profiles in mid-lactation Sarda dairy sheep with different body condition score

Pulina

Nudda

Battacone

et al. 2012

Italian Journal of Animal Science

View full text Add to dashboard Cite

Modulation by Galanin of Growth Hormone and Gonadotropin Secretion from Perifused Pituitary and Median Eminence of Prepubertal Male Calves

Cited by 27 publications

References 34 publications

Stimulation of Porcine Pituitary Luteinizing Hormone Release by Galanin: Putative Auto/Paracrine Regulation

Stimulation of Porcine Pituitary Luteinizing Hormone Release by Galanin: Putative Auto/Paracrine Regulation

Galanin’s Functional Significance in the Regulation of the Neuroendocrine Reproductive Axis of the Monkey

Effects of short-term feed restriction on milk yield and composition, and hormone and metabolite profiles in mid-lactation Sarda dairy sheep with different body condition score

Contact Info

Product

Resources

About