{'fraction_non_alphanumeric': 0.02679830747531735, 'fraction_numerical': 0.008815232722143865, 'mean_word_length': 4.674, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
The effect of sodium depletion with or without concomitant dehydration on Fos immunoreactivity in the different subregions of the subfornical organ and organum vasculosum of the lamina terminalis of the rat

In rats, each of the two forebrain sensory circumventricular organs, the subfornical organ (SFO) and organum vasculosum of the lamina terminalis (OVLT) can be categorised anatomically and functionally into subregions. The main divisions of the SFO are its outer shell and its ventromedial core, while the OVLT has a lateral zone, dorsal cap and a central vascular plexus. The aim of these experiments was to determine the effect of Na depletion for 24 hours by furosemide (20 mg/kg s.c.) treatment and low Na diet on rats (4 per group) with or without water available to drink on Fos immunoreactivity (Fos‐IR) in the subregions of the SFO and OVLT. We also examined the effect after 2 hours on these responses of correcting the Na deficit by drinking either isotonic 0.15M or hypertonic 0.3M NaCl. After these treatments, rats were killed by Na pentobarbitone (100 mg/kg i.p.) and standard immunohistochemical methods used to identify Fos in cell nuclei of CVO neurons. Whereas control untreated rats on low Na diet for 24 h exhibited minimal Fos‐IR in any subregions of the SFO and OVLT, rats subjected to sodium depletion with water available to drink exhibited many Fos‐labelled cells in the SFO that were almost exclusively confined to its ventromedial core, while in the OVLT, Fos expression was observed predominantly in the lateral zone with little Fos‐IR in the dorsal cap. Fos‐IR was not observed in the supraoptic nucleus (SON), signifying that the rats were not dehydrated. Treatment with the angiotensin AT1 receptor antagonist valsartan (5 mg/kg s.c. × 2 doses) inhibited the Fos response in the ventromedial core of the SFO. If water was withheld from Na‐depleted rats, some Fos‐IR was now observed in the outer shell, although most Fos‐IR was still observed in the ventromedial core; in the OVLT, Fos‐IR was observed in both its dorsal cap and lateral zone and the SON expressed Fos‐IR. Correction of the Na‐deficit in water‐replete but Na‐depleted rats by drinking 0.15M NaCl reduced the intensity, but did not abolish the Fos‐IR in the ventromedial core of the SFO or the lateral zone of the OVLT by 2 h, whereas water‐replete, Na‐depleted rats that drank hypertonic 0.3M NaCl exhibited additional Fos‐IR in the outer shell region of the SFO and in the dorsal cap of the OVLT as well as the less intense Fos‐IR in the ventromedial core of SFO and lateral zone of OVLT. These data confirm that the ventromedial core of SFO and lateral zone of the OVLT are activated by loss of body Na, whereas neurons in the outer shell of the SFO and dorsal cap of OVLT are more attuned to loss of body water and hypertonicity.