The study shows that giving calcitonin directly into the brain of rats sharply cuts down the natural pulses of growth hormone (GH). This suppression isn’t because more somatostatin (a hormone that blocks GH) is released, and it also makes the pituitary less responsive to GH‑releasing factor (GRF). In short, calcitonin can blunt GH spikes via a central brain mechanism.
Researchers made modified versions of glucagon, a hormone that raises blood sugar, and found some changes made it work much better at breaking down glycogen in rats. The most active version was over five times stronger than normal glucagon, while other tweaks made it weaker. These results show that certain spots on the glucagon molecule can be altered without losing function, and sometimes even improve it.
Heiman. M L ML; Murphy. W A WA; Nekola. M V MV; Lance. V A VA; Coy. D H DH
In rats, giving a growth hormone‑releasing factor (GRF) peptide for a few days made the pituitary gland more sensitive to that same peptide later on, but it didn’t change how the gland responded to a different hormone. This shows the gland can be “primed” by repeated GRF exposure.
Waelbroeck. M M; Robberecht. P P; Coy. D H DH; Camus. J C JC; De Neef. P P; Christophe. J J
The study shows that the natural growth‑hormone‑releasing factor (GRF‑1‑29) and several modified versions can bind to the same receptors that the hormone VIP uses in the rat pancreas. One specially modified peptide, (N‑Ac‑Tyr1,D‑Phe2)‑GRF(1‑29)‑NH2, blocks both VIP and GRF actions, acting like a VIP antagonist. Changing certain amino‑acid positions (especially 6 and 7) or swapping them for D‑forms makes the peptides less effective at stimulating the cell’s adenylate‑cyclase enzyme, while other swaps can make them even more active.
Marastoni. M M; Scaranari. V V; Fantini. F F; Sevignani. C C; Tomatis. R R
The study tested three versions of peptide T and a related peptide (VIP) on human skin cells grown in the lab. Two forms of peptide T and VIP each boosted cell growth, while a cyclic version of peptide T did not. Blocking VIP's receptor stopped VIP's effect but didn’t affect peptide T, suggesting they work through different pathways.
Delgado. M M; Garrido. E E; Martinez. C C; Leceta. J J; Gomariz. R P RP
The study shows that two brain‑derived peptides, VIP and PACAP, can protect young immune cells (CD4+CD8+ thymocytes) from dying when the body releases stress hormones like dexamethasone. When a short fragment of a related peptide, called GRF‑1‑29, blocks the VIP receptor, this protection is reduced, proving the effect works through that specific receptor.
The study shows that galanin can directly trigger growth hormone release from rat pituitary cells within seconds, without needing the brain's usual signals. This effect is quick, reversible, and works differently from the usual growth hormone‑releasing hormone.
Bongers. J J; Offord. R E RE; Felix. A M AM; Lambros. T T; Liu. W W; Ahmad. M M; Campbell. R M RM; H...
The paper compares different enzyme‑based ways to turn precursor forms of growth‑hormone‑releasing factor (GRF) into the active, amidated version. It shows that a recombinant enzyme can make the full‑length peptide almost completely, while trypsin can also do the job but with lower yields, especially for the shorter, super‑active 1‑29 version.
López de la Torre Casares. M M; Gargallo Fernández. M M; Moreno Esteban. B B; Rodrígu...
The study looked at six people with Sheehan's syndrome (a pituitary problem) and tested how their hormones responded to various challenges, including a dose of GRF‑1‑29, which normally makes the pituitary release growth hormone. All patients showed severe pituitary damage, and the GRF test helped show how the gland was functioning.
The study shows that a peptide called GRF‑1‑29, normally known for stimulating growth hormone, can also block the action of another peptide, VIP, which relaxes the gut. In lab experiments on guinea pig and rat intestines, GRF‑1‑29 reduced VIP‑driven muscle relaxation, though it was less potent than other VIP blockers.
Aasmul-Olsen. S S; Christensen. K A KA; Widmer. F F
Scientists showed that a special enzyme called carboxypeptidase can turn peptide acids into the more stable peptide amides that we usually want, like the active form of GRF‑1‑29. By using bigger, water‑loving side‑chains (like threonine) as the leaving group, they got better yields, and the method works even for longer peptides when the enzyme is made in a recombinant form.
Cacabelos. R R; Albarrán. M M; Diéguez. C C; Fariñas. F F; del Pino. J L JL; Expó...
The study looked at how a growth‑hormone‑releasing peptide (GRF‑1‑29) makes the body release GH in kids with ADHD compared to healthy kids. ADHD kids started with lower GH levels and showed a different pattern of GH release after the peptide, with some showing a strong response and others a weak one.
Pastoureau. P P; Barenton. B B; Blanchard. M M; Boivin. G G; Charrier. J J; Dulor. J P JP; Theriez....
Injecting GRF‑1‑29 into lambs quickly boosted their growth hormone levels, especially in under‑nourished animals. The treatment also shifted body composition by lowering fat storage and raising calcium and phosphorus in the bones, suggesting it can influence both metabolism and skeletal growth in ruminants.
Sauvant. D D; Kann. G G; Hervieu. J J; Disenhaus. C C
Giving goats twice‑daily shots of the peptide GRF‑1‑29 made them produce more milk. The goats ate a little more on their own, but the extra milk meant they ended up with a worse energy balance overall.
Ramos. M M; Fernández. A A; Ferrández. A A; Mayayo. E E; Guallar. A A
Giving a single IV dose of the peptide GRF‑1‑29 can help doctors figure out whether a person’s growth‑hormone problem comes from the brain (hypothalamus) or the pituitary gland. Some people who seem to have a hypothalamic issue don’t react to a one‑time dose, so they may need a longer or pulsed GRF regimen and thyroid hormone support. If there’s no reaction at all, the problem is likely in the pituitary and direct growth‑hormone therapy is needed.
The study tested a tiny dose of the peptide GRF‑1‑29 in kids with different types of short stature. It showed that the peptide can make growth hormone (GH) rise, but the rise is much smaller in kids who truly lack GH. However, some GH‑deficient kids still had a normal GH spike, so the test isn’t reliable for telling who has a GH problem.
Yang. Kai K; Trepanier. Catherine H CH; Li. Hongbin H; Beazely. Michael A MA; Lerner. Ethan A EA; Ja...
The study shows that a tiny amount of the hormone VIP can boost brain cell communication (NMDA receptors) through specific VPAC receptors and a cAMP/PKA signaling route, while a higher dose uses a different receptor (PAC1) and other pathways. The peptide GRF‑1‑29 blocks the VPAC‑mediated boost, meaning it can stop this effect.
Delgado. M M; De la Fuente. M M; Martínez. C C; Gomariz. R P RP
The study shows that two brain‑derived peptides, PACAP27 and PACAP38, can slow down the movement of mouse immune cells in a dish, likely by raising cAMP levels, and that a related peptide (VIP) does the same. It also suggests that the receptors these peptides use are similar, and that a specific antagonist can partly block their effect.
Wu. D D; Chen. C C; Zhang. J J; Katoh. K K; Clarke. I I
In a lab test using sheep pituitary cells, the new peptide GHRP‑1 (also called KP‑101) was shown to make the cells release growth hormone, but it needed a higher concentration to work and never reached the maximum effect that the classic hormone‑releasing factor (GRF) could achieve. The effect depended on calcium channels, and the peptide behaved similarly to the older GHRP‑6. These results come from an in‑vitro experiment, not from human trials.
Sung. K J KJ; Chang. S E SE; Paik. E M EM; Lee. M W MW; Choi. J H JH
The study shows that the peptide VIP makes skin cells (keratinocytes) grow faster, but it does this by boosting a growth factor called TGF‑alpha rather than the usual cAMP pathway. This effect happens even when the usual PKA blocker is present, and short pieces of VIP work the same way. The finding is mainly about skin biology, not about overall health or performance.