Oxytocin interference in the effects induced by inhalation of 7.5% CO(2)  in healthy volunteers.
OBJECTIVE
The objective of this study was to assess the acute effect of intranasally administered oxytocin (OT) on subjective states, cardiovascular, and endocrine parameters in healthy volunteers who inhaled 7.5% CO(2) .


METHODS
Forty-five subjects were allocated into three matched groups of subjects who received 24 international units (IU) of OT, 2 mg of lorazepam (LZP), or placebo (PL). The challenge consisted of medical air inhalation for 20 min, 10 min of rest, and CO(2) 7.5% inhalation for 20 min. Subjective effects were evaluated by self-assessment scales; heart rate, blood pressure, skin conductance, and salivary cortisol were also measured. Assessments were performed at four time points: (i) baseline (-15 min); (ii) post-air inhalation (90 min); (iii) post-CO(2) inhalation (120 min), and (iv) post-test (160 min).


RESULTS
CO(2) inhalation significantly increased the anxiety score in the PL group compared with the post-air measurement but not in the OT or LZP groups. The LZP reduced anxiety after medical air inhalation. Other parameters evaluated were not affected by OT.


CONCLUSIONS
OT, as well as LZP, prevented CO(2) -induced anxiety, suggesting that this hormone has anxiolytic properties.
Department of Neuroscience and Behavior, Faculty of Medicine of Ribeirão Preto, and National Institute for Translacional Medicine (INCT-TM, CNPq), University of São Paulo, Ribeirão Preto, Brazil.
Danielle Chaves Gomes
DC
de Oliveira
Marcos Hortes N
MH
Chagas
Luis Vicente
LV
Garcia
José Alexandre S
JA
Crippa
Antonio W
AW
Zuardi
D000280:Administration, Inhalation; D000281:Administration, Intranasal; D000328:Adult; D014151:Anti-Anxiety Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001007:Anxiety / Q000517:prevention & control*; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000008:administration & dosage / Q000009:adverse effects; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D008140:Lorazepam / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010121:Oxytocin / Q000008:administration & dosage / Q000494:pharmacology*; D012463:Saliva / Q000737:chemistry; D016037:Single-Blind Method; D012867:Skin / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
D014151:Anti-Anxiety Agents; D002245:Carbon Dioxide; D010121:Oxytocin; D008140:Lorazepam; D006854:Hydrocortisone