Inhibition of the LH Surge by Restraint Stress in Cyclic Rats: Studies on the Role of GABAA and GABAB Receptors

There is evidence that stress can alter the activity in the brain of gamma-aminobutyricacid (GABA), a neurotransmitter that has been implicated in the regulation of LH secretion. In the present study the role of GABA in the restraint stress-induced inhibition of the LH surge was investigated in the intact cyclic rat. Intracerebroventricular (icv) administration of the GABAA receptor agonist muscimol (0.1, 0.5 or 1 μg) 5 min before the presumed onset of the pro-oestrous LH surge (at 0900 h) caused a dose dependent suppression of the surge. A single dose of the GABAB receptor agonist baclofen (1 μg; icv) injected at 0855 h postponed the onset of the LH surge, and repeated injections at 0855 and 1130 h suppressed the surge. These data indicate that GABA-ergic activity in the brain can inhibit the LH surge in the cyclic rat via GABAA and GABAB receptors. Pro-oestrous rats were subjected to 5 hrs of restraint starting at 0855 h. Pretreatment with the GABAA receptor antagonist bicuculine (1 μg; icv) at 0840, 0940 and 1040 h or pretreatment with the GABAB receptor antagonist phaclofen (10 μg; icv) at 0840 h were ineffective in preventing the restraint-induced inhibition of the LH surge. The results suggest that GABAA and GABAB receptors are not involved in the inhibitory effect of restraint stress on the LH surge.     

Assessing Patients’ Beliefs About Their Cancer-Related Fatigue: Validation of an Adapted Version of the Illness Perception Questionnaire

Cancer-related fatigue (CRF) is a common and distressing side-effect of cancer treatment. The present study developed a brief version of the Illness Perception Questionnaire (IPQ) for assessing patients' representations of CRF. Cancer patients and survivors (n?=?155) completed a revised version of the IPQ as well as measures of fatigue severity at two different time-points. Confirmatory factor analysis at both Time 1 and 2 showed that the seven-factor solution based on the Self-Regulation Model fit the data adequately and factorial invariance over the two time-points was supported. The resulting subscales exhibited good internal consistency and test-retest reliability. The adapted version of the IPQ shows promise for the assessment of patient perceptions regarding CRF. The scale may be able to be used clinically to identify if patients have inaccurate or unhelpful representations of CRF and to help tailor interventions for persistent fatigue in cancer survivors.