Table 3.
Clinical endogenous neuropeptide measurement studies.
| Article title | First author & publication year |
Sample characteristics | Substrates & measurement techniques | Relevant findings |
|---|---|---|---|---|
| “Alterations in the hypothalamic paraventricular nucleus and its oxytocin neurons (putative satiety cells) in Prader-Willi syndrome: a study of five cases” | Swaab et al. (1995) | Human adult study; postmortem tissue Age range: 22–64 y PWS: n = 5 Females: 3 Males: 2 Control: n = 5 Females: 3 Males: 2 (Additional 27 adult controls, i.e., 14 males and 13 females) |
Substrates: OXT and AVP Collection Location: hypothalamus (PVN) Techniques: ICC |
-Significant decrease in the volume (28%) of the PVN and the total cell numbers (38%) in the PVN was detected in the PWS cases compared to five matched controls -Significant decrease in the volume (54%) and the number (42%) of OXT neurons in the PVN was found in the PWS cases compared to five matched controls -The number of AVP neurons in the PVN was not significantly different in the PWS cases, but only the size of the nucleus was increased compared to five matched controls -Significant decrease in the number of OXT neurons and unaffected number of AVP neurons in the PVN of PWS cases remained consistent when compared to additional 27 controls |
| “Attenuation of the polypeptide 7B2, prohormone convertase PC2, and vasopressin in the hypothalamus of some Prader-Willi patients: indications for a processing defect” | Gabreëls et al. (1998) | Human adult study; postmortem tissue Age range: 19–88 y PWS: n = 7 Females: 4 Males: 3 Control: n = 11 Females: 5 Males: 6 |
Substrates: OXT and AVP Collection Location: hypothalamus (SON; PVN) Techniques: ICC |
-Normal staining intensity for OXT was found in the magnocellular neurons of the PVN and SON in all PWS cases relative to controls -The magnocellular neurons of SON and PVN in two PWS cases who were deficient for neuroendocrine polypeptide 7B2 did not show processed AVP and prohormone convertase 2 immunoreactivity, but showed normal immunoreactivity for AVP precursor relative to controls -Two other PWS cases showed moderate processed AVP immunoreactivity along with some degree of 7B2 immunoreactivity in the magnocellular neurons of SON and PVN relative to controls -Remaining three PWS cases showed normal processed AVP immunoreactivity in the magnocellular neurons of SON and PVN relative to controls |
| “Cerebrospinal fluid levels of oxytocin in Prader–Willi syndrome: a preliminary report” | Martin et al. (1998) | Human adolescent and adult study Age range: 16–28 y PWS: n = 5 Females: 3 Males: 2 Control: n = 6 Female: 6 Male: 0 |
Substrates: OXT and AVP Collection Location: cerebrospinal fluid via lumbar puncture Technique: RIA (unspecified if sample extraction was performed) |
- CSF OXT levels were significantly higher in the PWS cases compared to controls, and this finding was more prominent when males were excluded from the analysis -CSF AVP levels were not significantly different between the groups with both female and male subjects, but significantly lower in female PWS cases when excluding males from the analysis |
| “Peptides associated with hyperphagia in adults with Prader–Willi syndrome before and during GH treatment” | Höybye et al. (2003) | Human adolescent and adult study Age range: 17–32 y PWS: n = 17 Females: 8 Males: 9 |
Substrate: OXT Collection Location: peripheral blood Technique: RIA after solid phase extraction |
-Baseline plasma OXT levels were within the normal range but considered low with relevance to their obesity - Significant negative correlation was found between plasma OXT and anorexigenic hormone leptin levels in serum at baseline |
| “Whole genome microarray analysis of gene expression in Prader-Willi syndrome” | Bittel et al. (2007) | Human infant, adolescent, and adult study; included postmortem tissue Age range: 1–45 y PWS: n = 10 Females: 3 Males: 7 Control: n = 6 Females: 3 Males: 3 |
Substrate: OXTR Collection Location: lymphoblastoid cells and frontal cortex brain tissue Techniques: microarray; qPCR |
-Significant reduction in expression of OXTR in PWS cases relative to controls was found in both lymphoblastoid cells and frontal cortex |
| “Elevated plasma oxytocin levels in children with Prader–Willi syndrome compared with healthy unrelated siblings” | Johnson et al. (2016) | Human child study Age range: 5–11 y PWS: n = 23 Females: 10 Males: 13 Controls: n = 18 Females: 8 Males: 10 |
Substrate: OXT Collection location: peripheral blood Technique: multiplex sandwich immunoassays (no sample extraction) |
-Plasma OXT levels were significantly increased in the PWS cases compared to healthy unrelated siblings of children with PWS -PWS diagnosis predicted the OXT levels in regression analyses with an overall model fit -Significant positive correlation between OXT levels and age was only found in females with PWS |
AVP, arginine vasopressin; CSF, cerebrospinal fluid; GH, growth hormone; ICC, immunocytochemistry; OXT, oxytocin; OXTR, oxytocin receptor; PVN, paraventricular nucleus; PWS, Prader-Willi syndrome; qPCR, quantitative polymerase chain reaction; RIA, radioimmunoassay; SON, supraoptic nucleus