Nicklin. L T LT; Robinson. R S RS; Marsters. P P; Campbell. B K BK; Mann. G E GE; Hunter. M G MG
Scientists discovered that cow ovarian cells have leptin receptors, but leptin alone doesn’t boost the hormone progesterone. However, when the cells are also given IGF‑1 LR3, leptin suddenly increases progesterone production. This shows IGF‑1 LR3 can amplify leptin’s effect on steroid hormone output in bovine tissue.
Levolger. S S; Wiemer. E A C EAC; van Vugt. J L A JLA; Huisman. S A SA; van Vledder. M G MG; van Dam...
In mice with cancer‑induced muscle loss, blocking the ALK4/5 receptors with the drug GW788388 stopped most of the weight and strength loss, while the IGF‑1 LR3 peptide helped keep muscle size but also made the tumors grow faster.
Pesall. J E JE; McFarland. D C DC; McMurtry. J P JP; Clapper. J A JA; Francis. G L GL; Gilkerson. K...
The study found that the LR3 version of IGF‑1, which is altered to avoid binding proteins, actually worked worse than normal IGF‑1 in turkey muscle cells, and that changes meant to dodge binding proteins can also lower the peptide’s ability to stick to its main receptor.
Glister. C C; Tannetta. D S DS; Groome. N P NP; Knight. P G PG
This study looked at how a lab‑made version of IGF‑1 (LR3 IGF‑I) and the hormone FSH affect hormone production in cow ovarian cells. LR3 IGF‑I alone boosted several hormones, especially estrogen‑related ones, and worked together with low doses of FSH, but at high doses it actually reduced some effects. The findings hint that IGF‑1 LR3 can influence ovarian hormone balance, but the work was done in isolated bovine cells, not humans.
Sundgren. Nathan C NC; Giraud. George D GD; Schultz. Jess M JM; Lasarev. Michael R MR; Stork. Philip...
The study shows that a special form of IGF‑1 (LR3 IGF‑1) makes fetal sheep heart cells divide, but it doesn’t make them bigger or cause them to have extra nuclei. Both the ERK and PI3K pathways are needed for this cell‑division effect, and blocking either one stops it.
Reiter. B C BC; Kamanga-Sollo. E E; Pampusch. M S MS; White. M E ME; Dayton. W R WR
The study shows that a cell‑surface receptor called EGFR is needed for a growth factor called LR3‑IGF‑1 to make muscle‑type cells multiply. When EGFR is blocked or its levels are lowered, LR3‑IGF‑1 can’t boost cell growth, likely because EGFR also helps keep the IGF‑1 receptor protein around. This was seen in cow muscle cells, not humans, and the work was done in a lab setting.
The study used sheep ovarian cells to see how different doses of LH, insulin, IGF‑1 LR3 and EGF affect cell growth and hormone output. It found that low LH boosts androgen (androstenedione) production, while higher LH later shifts cells toward progesterone and luteinization. IGF‑1 LR3 (and insulin) increased cell numbers and androgen production but lowered progesterone, showing a dose‑dependent effect.
Brankin. Victoria V; Mitchell. Marcus R P MR; Webb. Bob B; Hunter. Morag G MG
This pig‑ovary cell study shows that IGF‑1 LR3, together with signals from the egg, can make ovarian support cells (granulosa and theca) grow more and change hormone output, while a peptide called stem cell factor (SCF) tweaks progesterone levels. The work is done in a dish, not in people, so it’s mostly a mechanistic glimpse rather than a ready‑to‑use protocol.
Stremming. Jane J; Heard. Sara S; White. Alicia A; Chang. Eileen I EI; Shaw. Steven C SC; Wesolowski...
Giving a short‑acting IGF‑1 variant (LR3 IGF‑1) to unborn sheep for a week made some organs like the heart and adrenal gland a bit bigger, but it didn’t make the whole fetus heavier and didn’t boost blood flow or nutrient delivery from the placenta. In fact, the fetuses took up fewer amino acids, yet they still grew those organs, likely because they used the available nutrients more efficiently.
Glister. Claire C; Groome. Nigel P NP; Knight. Philip G PG
The study shows that a synthetic IGF‑1 analogue (LR3‑IGF‑1) makes cow ovarian cells produce more hormones, but nearby egg cells release a protein (TGF‑alpha) that can block many of those hormone‑boosting effects. This interaction was seen only in a lab dish with cow cells, not in humans.
In cow ovarian cells, the growth factor IGF‑1 LR3 can boost DNA building, especially in the outer cumulus cells, but hormones that make these cells turn into a more mature, mucus‑producing state (like FSH, EGF, or dbcAMP) block that boost. The block isn’t because of competing binding proteins, but because the cells are changing their role and stop dividing.
White. Alicia A; Stremming. Jane J; Wesolowski. Stephanie R SR; Al-Juboori. Saif I SI; Dobrinskikh....
In a study on sheep fetuses that were not growing well because of a weak placenta, giving them IGF‑1 LR3 for a week did not make them bigger, nor did it change their insulin or sugar‑handling. It did lower their blood amino acids, which might mean the bodies used more building blocks, but overall the treatment didn’t help the growth problem.
Allegrucci. C C; Hunter. M G MG; Webb. R R; Luck. M R MR
The study created a lab system where two types of cow ovarian cells grow together on a protein surface without serum. Adding LR3‑IGF‑1 (a long‑acting IGF‑1 version) along with other hormones changed how these cells made sex hormones, but the work was done in isolated cells, not in living animals or people.
This rat study looked at how a special form of IGF‑1 (LR3‑IGF‑1) and fertility hormones affect two kinds of ovarian cells. It found that the cells surrounding the egg grow faster than the wall cells, and each cell type reacts differently to IGF‑1. The hormones can work alone or together, but IGF‑1 isn’t the only driver of growth.
Campbell. B K BK; Souza. C J H CJ; Skinner. A J AJ; Webb. R R; Baird. D T DT
The study looked at sheep ovarian cells and found that the IGF‑1 LR3 analog works together with bone‑morphogenetic proteins (BMP‑2,‑4,‑6) to boost hormone production, especially in sheep with a specific FecB mutation. These results are specific to sheep ovaries and don’t give clear guidance for human use.
A rat study looked at how a hormone that mimics FSH (eCG) and a special form of IGF‑1 (LR3‑IGF‑I) affect the growth of cells that surround an egg. The results showed that eCG combined with FSH gave the biggest boost in cell growth, while LR3‑IGF‑I alone didn’t help, and the two didn’t seem to work together the way some people thought.
In rats, the IGF‑1 analogue LR3‑IGF‑I changes how two types of ovarian cells grow and make hormones: it makes mural granulosa cells multiply more but reduces growth in cumulus cells, and it also flips progesterone production the opposite way. This shows IGF‑1 can act very differently depending on the cell type, but the findings are specific to ovarian tissue and not directly useful for general health or performance goals.
Haluska. Paul P; Carboni. Joan M JM; Loegering. David A DA; Lee. Francis Y FY; Wittman. Mark M; Saul...
This study tested a drug that blocks the IGF‑1 and insulin receptors and found it can slow cancer cell growth and shrink tumors in mice, but it doesn’t tell you how to use IGF‑1 LR3 for performance or health.
Prelle. K K; Stojkovic. M M; Boxhammer. K K; Motlik. J J; Ewald. D D; Arnold. G J GJ; Wolf. E E
In a lab study using cow embryos, the researchers compared regular IGF‑I with a modified version called LR3. LR3 doesn’t stick to the body’s natural IGF‑binding proteins as much, so it acted faster early on, helping embryos split more quickly and ending up with slightly more cells, especially in the outer layer. Regular IGF‑I helped later stages of development better. The study also showed that each peptide changes the embryos’ own IGF‑binding protein and receptor gene activity in different ways.
Shen. Zanming Z; Martens. Holger H; Schweigel-Röntgen. Monika M
A lab test on sheep showed that a synthetic IGF‑1 peptide quickly boosts sodium movement across the stomach lining, but this effect is specific to sheep gut cells and doesn’t translate into any clear human health or performance benefit.