Effect of sublethal exposure of Cartap on hypothalamo-neurosecretory system of the freshwater spotted murrel, Channa punctatus (Bloch)

D.K. Mishra¹, K. Bohidar² and A.K. Pandey*³

¹Department of   Zoology, Deogarh College, Deogarh-768 119, India

²Department of Zoology, Utkal University, Vani Vihar, Bhubaneswar-751 004, India

³Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar-751 002, India

(Received: January 01, 2007; Revised received: July 19, 2007; Accepted: July 08, 2007)

Abstract: In order to record the effect of carbamate pesticide on hypothalamus of Channa punctatus, fish were exposed to sublethal concentration  (0.18 mg l^-1, 30% LC₅₀ for 96 hr) of Cartap for 24, 48, 72 and 96 hr under static bioassay condition. Hypothalamo-neurosecretory complex of the murrel consisted mainly of nucleus preopticus (NPO), nucleus lateralis tuberis (NLT) and their axonal tracts. NPO is a paired structure situtated on either side of the third ventricle anterodorsal to the optic chiasma and looked inverted L-shape in the sagittal section. NPO is morphologically divisible into a dorsal pars magnocellularis (PMC) consisting of large neurons and ventral pars parvocellularis (PPC) formed of smaller neurosecretory cells. NLT cells are distributed in the infundibular floor adjacent to the pituitary stalk. Sublethal Cartap treatment induced an initial hypertrophy of the neurosecretory cells of NPO and NLT followed by loss of staining affinity as well as varying degrees of cytoplasmic vacuolization and necrosis. Herring bodies (HB) were also encountered in the neurohypophysis of the treated fishes. 

Key words: Cartap, Hypothalamo-neurosecretory complex, Hypophysial vesicle, Channa  punctatus

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