Table 3.
Summary of main neuropeptide levels in the circulation in both clinical HD and rodent HD models
| Neuropeptide | HD stage | HD rodent models | References | ||
| Output from the hypothalamus | |||||
| ACTH | = | Serum, plasma levels (premanifest, HD stage 2-3) | ↑ | Serum levels (R6/2) | [104, 106, 176] |
| ↑ | Plasma levels (HD stage 1–4) | [126] | |||
| AgRP | ↑ | Plasma levels (premanifest) | Not assessed | [177] | |
| ↓ | Plasma levels (manifest) | [177] | |||
| CART | ↑ | CSF levels (early-mid stage HD) | Not assessed | [105] | |
| Cortisol/corticosterone | ↑ | Plasma, serum levels (HD stage 1–4) | ↑ | Serum levels (R6/2) | [106, 107, 126, 176, 178–180] |
| = | Serum levels (premanifest, HD stage 2-3) | = | Serum levels (BACHD) | [104, 116] | |
| Estradiol | = | Serum levels (premanifest, HD stage 2-3) | = | Serum levels (R6/1) | [104, 181] |
| FSH | = | Serum, plasma levels (premanifest, HD stage 2-3) | Not assessed | [104, 176] | |
| GHRF | = | Serum levels (premanifest, HD stage 2-3) | Not assessed | [104] | |
| Growth hormone | = | Serum and plasma levels (early HD, manifest) | Not assessed | [182, 183] | |
| ↑ | Plasma levels (manifest) | [176] | |||
| ↓ | Plasma levels (manifest) | [177] | |||
| IGF-1 | = | Plasma levels (manifest) | ↑ | Plasma levels (BACHD, YAC128) | [183, 184] |
| LH | = | Serum, plasma levels (premanifest, HD stage 2-3) | Not assessed | [104, 176] | |
| NPY | ↑ | CSF levels (early-mid stage HD) | Not assessed | [185] | |
| Orexin | = | Ventricular CSF (HD grade 1–4) | = | CSF levels (YAC128) | [51, 100, 101, 103, 130] |
| Prolactin | = | Serum, plasma levels (premanifest, HD stage 2-3) | Not assessed | [104, 176, 186, 187] | |
| ↓ | Plasma (premanifest and manifest) | [177] | |||
| Testosterone | = | Serum, plasma levels (premanifest, HD stage 2-3) | ↓ | Serum levels (R6/1, R6/2) | [104, 139, 176, 181, 188, 189] |
| ↓ | Plasma levels (manifest) | ↑ | Serum levels (tgHD rat) | [190, 191] | |
| TSH | = | Serum, plasma levels (premanifest, HD stage 2-3) | Not assessed | [104, 176, 186] | |
| Vasopressin | = | Serum levels (premanifest, HD stage 2-3) | = | Serum (BACHD) | [104, 116] |
| Input to the hypothalamus | |||||
| Adiponectin | = | Plasma levels (early HD) | ↓ | Serum levels (R6/2,N171-82Q) | [177, 182, 192] |
| Amylin | ↑ | Plasma (premanifest and manifest) | Not assessed | [177] | |
| Ghrelin | = | Plasma levels (early HD) | ↓ | Serum levels (R6/2,N171-82Q) | [110, 182, 192] |
| ↑ | Plasma (manifest) | [177, 183] | |||
| GIP | = | Plasma (premanifest and manifest) | Not assessed | [177] | |
| Glucagon | ↓ | Plasma (manifest) | Not assessed | [177] | |
| Glucose | = | Plasma levels (manifest) | ↑ | Serum levels (R6/2, R6/1, N171-82Q) | [106, 183, 192–195] |
| Insulin | = | Plasma levels (HD grade 1-2, manifest) | ↑ | Serum levels (R6/2) | [106, 177, 183, 193, 194, 196] |
| ↓ | Serum levels (R6/2, N171-82Q) | [192] | |||
| Leptin | = | Plasma levels (early HD) | ↑ | BACHD, BAC-225Q, YAC128 | [114, 116, 197–199] |
| ↓ | Plasma (manifest) | ↓ | Serum levels (R6/2,N171-82Q) | [177, 183, 192, 200] | |
| PP | = | Plasma (premanifest and manifest) | Not assessed | [177] | |
| PYY | = | Plasma (premanifest and manifest) | Not assessed | [177] | |
| Resistin | = | Plasma levels (early HD) | Not assessed | [197] |
ACTH, adrenocorticotropic hormone; AgRP, agouti-related protein; CART, cocaine and amphetamine regulated transcript; FSH, follicle-stimulating hormone; GHRF, growth hormone-releasing factor; IGF-1, insulin-like growth factor 1; LH, luteinizing hormone; NPY, neuropeptide Y; TSH, thyroid-stimulating hormone; GIP, gastric inhibitory polypeptide; PP, pancreatic polypeptide; PYY, peptide YY.