Distribution of luteinizing hormone-releasing hormone in the upper brainstem and diencephalon of the cat: An immunocytochemical study

The distribution of luteinizing hormone-releasing hormone (LH-RH)-immunosta ined cell bodies and fibres was studied in the brainstem and diencephalon o f the cat using an indirect immunoperoxidase technique. The brainstem and t he thalamus were devoid of immunostained cell bodies, whereas in the hypoth alamus immunopositive perikarya were observed in the supraoptic nucleus, th e anterior hypothalamus, the preoptic region and in the arcuate nucleus. Ou r findings also showed that the hypothalamus is richer in immunostained fib res, and that in this region such fibres are more widely distributed than i n the thalamus and upper brainstem. No immunopositive fibres were observed in the lower brainstem. Our results point to a more widespread distribution of LH-RH-immunostained perikarya in the cat hypothalamus than that previou sly reported in the cat; a similar distribution to that found in the rat, a nd a more restricted distribution than in primates. Additionally, our study shows a more widespread distribution of immunostained fibres in the cat br ainstem and diencephalon than that previously described for other mammals. In this context, our results describe for the first time in the mammals cen tral nervous system fibres containing LH-RH located in the stria medullaris of the thalamus, the supra mammillary decussation, the laterodorsal and la teroposterior thalamic nuclei, the nucleus reuniens, the supraoptic nucleus , and the optic chiasm. Thus, our findings reveal that LH-RH-immunostained structures are widely distributed in the upper brainstem and in the diencep halon of the cat, suggesting that the peptide may be involved in several ph ysiological functions. (C) 2000 Elsevier Science Inc.