Arrest of pulsatile luteinizing hormone (LH) secretion during insulin-induced hypoglycemia (IIH): Improvement by intrahypothalamic perfusion with glucose

Insulin-induced hypoglycemia (IIH), as with many other acute stressors, res trains the activity of the reproductive axis, reducing luteinizing hormone (LH) release. In adult ovariectomized, steroid-primed rats, we investigated the effect of III-I and of mediobasal intrahypothalamic perfusion with glu cose (200 mg/dl) on pulsatile LH secretion. IIH led to a significant decrea se in all pulsatility parameters studied using PC-Pulsar analysis, e.g. pul se amplitude and frequency, maximum and baseline LH levels (p< 0.05 versus control), and LH overall mean release (p < 0.01 versus control). Intrahypot halamic perfusion with glucose normalized LH pulse frequency, improved maxi mum and baseline levels, and partially ameliorated LH pulse amplitude and o verall mean release. Thus, our results show that the glucoprivic cessation of LH release is restored, at least partially, by an adequate glucose suppl y to the hypothalamus; it is proposed, in view of these and previous result s, that different mechanisms in the CNS may be involved in LH suppression o bserved during IIH.