Attempts to characterize the convulsive response of parathyroidectomized rats to pineal gland removal

If thyroparathyroidectomized or parathyroidectomized (PTX) immature male rats are pinealectomized (PX) most (approx. 80%) of them experience numerous convulsive seizures within 8 hr after removal of the pineal gland. The postconvulsive mortality (by 48 hr after pinealectomy) is about 30%. Other surgical procedures involving opening of the skull, such as olfactory bulbectomy or unilateral transection of the nervi conarii, do not initiate convulsions in PTX rats. Likewise, denervation of the pineal gland by superior cervical ganglionectomy (SCGX) in PTX rats is not followed by seizures. However, if PTX + SCGX rats are subsequently subjected to pineal gland removal they experience the convulsions. This latter finding suggests that the pineal gland may remain functional after sympathetic denervation. The injection of calcium lactate does not protect against the seizures in PTX + PX rats. If the operations are reversed, i.e., if pineal gland removal precedes PTX by one week the rats do not exhibit the convulsive behavior. Whole brain norepinephrine is depressed in convulsing rats while serotonin and dopamine levels remain unchanged.